HK1126583A - Methods and apparatus for controlling a base station's transmission power - Google Patents

Abstract

A base station receives loading information indicative of the loading of other base stations and determines a downlink transmission power budget as a function of the received loading factor information. The base station may decrease/increase a current power budget dedicated to downlink traffic channel segments in response to detecting an increase/decrease in loading at an adjacent base station. Thus, base stations operate in a cooperative manner reducing power output, in at least some cases, where loading at a neighboring base station increases thereby reducing the interference to the base station with the increased load. A base station can consider possible alternative transmission power levels, estimated levels of interference, and/or possible alternative data rates in making trade-off decisions regarding downlink power budget.

Description

Method and apparatus for controlling transmission power of base station

Claiming priority under 35U.S.C. § 119

The present application is a partially-filed application of U.S.11/251,069 filed on 14/10/2005, a partially-filed application of U.S. patent application 11/302,729 filed on 14/12/2005, a partially-filed application of U.S. patent application 11/486,714 filed on 14/7/2006, and a partially-filed application of U.S. application 11/487,017 filed on 14/7/2006, each of which is expressly incorporated herein by reference.

Technical Field

The present disclosure relates to wireless communication systems and, more particularly, the present disclosure relates to power control in wireless communication systems.

Background

In a wireless communication system including multiple base stations, where at least some of the base stations use the same radio resource, e.g., spectrum, downlink transmissions from one base station may interfere with downlink transmissions of other base stations (e.g., neighboring base stations) using the same spectrum. The downlink traffic channel loading condition at a particular base station attachment point typically varies over time by a number of factors including: number of users, type of user, type of application in use, amount of data to be communicated, fault tolerance, latency requirements, channel conditions, error rate, and location of the wireless terminal. Varying the transmission power level of a traffic channel segment may affect the information data rate achievable by a particular wireless terminal, but also from the perspective of other wireless terminals, changes the interference level of other wireless terminals connected to different base station attachment points of another base station (e.g., a neighboring base station) using the same spectrum.

By using a fixed downlink transmission power budget for each base station attachment point, the overall downlink interference in the system can be controlled. The power associated with different sub-channels within a downlink traffic channel may vary with the overall downlink power budget maintained at a fixed level. This approach tends to limit the overall interference in the system, but does not take advantage of different system load conditions to optimize throughput.

It would be advantageous if a base station was not limited to a single downlink power budget but could vary its downlink transmission power budget in response to varying load conditions at itself or nearby base stations. It is beneficial if neighboring base stations exchange load information, thus allowing the base stations to make timely decisions about downlink transmission power levels. Furthermore, it is beneficial if the power budget decision of a particular base station is performed at said base station, since said base station has easily available relevant information, such as current load conditions, current channel conditions, user profile, detected changes, applications in progress, thus facilitating a fast notification response to changing conditions.

Disclosure of Invention

Various embodiments are directed to methods and apparatus for communicating, collecting, measuring, reporting and/or using information that may be used for interference control purposes, load management and/or dynamic changes in a base station downlink power budget.

According to various embodiments, a base station receives loading information indicative of the loading of other base stations (e.g., neighboring base stations), and the base station determines a downlink transmission power budget based on the received loading factor information. For example, the base station may decrease the current power budget dedicated to the downlink traffic channel segment in response to detecting an increase in the load of the neighboring base station. The base station may increase the current power budget dedicated to the downlink traffic channel segment in response to detecting a decrease in the load of the neighboring base station. Thus, the base stations operate in a cooperative manner that reduces power output, in at least some cases (where the load of neighboring base stations increases), thereby reducing interference to base stations with increased load. This is in sharp contrast to systems that may attempt to increase power output in response to increased loading of neighboring base stations to overcome the increased interference generated by neighboring base stations with increased communication load. The method and apparatus are particularly suited for use in a communication system comprising a plurality of base stations that may interfere with each other. This is because in a wireless communication system including multiple base stations, downlink transmissions from one base station create interference with respect to other base stations (e.g., neighboring base stations) using the same frequency spectrum. The base station may take into account possible alternative transmission power levels, estimated interference levels, and/or possible alternative data rates to make trade-off decisions regarding the downlink power budget (e.g., for the downlink traffic channel).

An exemplary method of operating a first base station according to various embodiments includes: receiving second base station loading factor information indicative of a loading of a second base station attachment point corresponding to a second base station; and determining a downlink transmission power budget from said received second base station loading factor information. An exemplary base station according to various embodiments includes: an interface for receiving a signal conveying base station loading factor information indicative of loading of at least one base station attachment point corresponding to at least one other base station; a loading factor information recovery module for recovering loading factor information corresponding to at least one other base station from the received signal; and a downlink transmission power budget determination module, wherein the downlink transmission power budget determination module determines a downlink transmission power budget for an attachment point of at least one other base station based on the recovered loading factor information corresponding to the base station.

While various embodiments have been discussed in the summary above, it should be understood that not all embodiments need include the same features, and some of the features described above are not required and may be required in some embodiments. Numerous additional features, embodiments and benefits of the present invention are discussed in the detailed description which follows.

Drawings

Fig. 1 is a diagram of an exemplary wireless communication system implemented in accordance with various embodiments.

Fig. 2 is a diagram of an exemplary base station in accordance with various embodiments.

Fig. 3 is a diagram of an exemplary wireless terminal, in accordance with various embodiments.

Fig. 4 is a diagram of a flow chart of an exemplary method of operating a first base station in a multiple access wireless communication system including multiple base stations, in accordance with various embodiments.

Fig. 5 is a diagram of a flow chart of an exemplary method of operating a first base station in a multiple access wireless communication system including multiple base stations, in accordance with various embodiments.

Fig. 6 is a diagram of a flow chart 600 of an exemplary method of operating a first base station in a multiple access wireless communication system including multiple base stations, in accordance with various embodiments.

Fig. 7 is a diagram illustrating features of various embodiments, wherein a base station in a wireless communication system including a plurality of base stations receives loading factor information corresponding to another base station and determines a downlink transmission power budget based on the received base station loading factor information.

Fig. 8 is a diagram illustrating features of various embodiments, wherein a base station in a wireless communication system including a plurality of base stations receives loading factor information corresponding to another base station and determines a downlink transmission power budget based on the received base station loading factor information.

Fig. 9 is a diagram illustrating features of various embodiments, wherein a base station in a wireless communication system including a plurality of base stations receives loading factor information corresponding to another base station and determines a downlink transmission power budget based on the base station loading factor information.

Fig. 10, which includes the combination of fig. 10A and 10B, is a diagram of a flow chart of an exemplary method of operating a base station in accordance with various embodiments.

Detailed Description

Fig. 1 is a diagram of an exemplary wireless communication system 100, such as a multiple access OFDM wireless communication system, in accordance with various embodiments. The exemplary wireless communication system 100 includes a plurality of base stations (base stations 1102, 104), and a network node 110. Each base station (102, 104) includes at least one base station attachment point. A base station (102, 104) may include one or more sectors and use one or more carriers. For example, in some embodiments of some base stations, the base station attachment point corresponds to a combination of a cell and a carrier. In some embodiments, the base station attachment points of some base stations correspond to combinations of cells, sectors, and carriers. Network node 110 is coupled to (base station 1102, base station M104) via network links (120, 122), respectively. Network node 110 is also coupled to other network nodes and/or the internet via network link 124. Network links 120, 122, 124 are, for example, fiber optic links, wired links, and/or wireless links. Each base station (base station 1102, base station M104) has a corresponding radio coverage area (cell 1106, cell M108), respectively.

Communication system 100 also includes a plurality of wireless terminals, such as mobile nodes, that are mobile throughout the system and are connected to base stations whose coverage areas the wireless terminals are currently located within. Wireless terminals (WT 1112,.., WT N114) currently located in cell 1106 are coupled to base station 1102 via wireless links (126,.., 128), respectively. Wireless terminals (WT1 ' 116, WT.., WT N ' 118 ') currently located in cell M108 are coupled to base station M104 via wireless links (130, 130.., 132), respectively.

At least some of the base stations in system 100 consider load information from other base stations (e.g., neighboring base stations) in addition to their own loads and dynamically adjust their downlink transmission power budget, for example, according to the loads of other base stations (e.g., neighboring base stations). In some embodiments, a base station makes its own independent determination of its downlink power budget for one of its base station attachment points, but makes that determination with the received loading information of other base stations (e.g., neighboring base stations) in the local vicinity.

Fig. 2 is a diagram of an exemplary base station 200 implemented in accordance with various embodiments. Exemplary base station 200 may be any of the base stations of fig. 1 or 4 or 5 or 6. The exemplary base station 200 includes a receiver module 202, a transmitter module 204, a processor 206, an I/O interface 208, and a memory 210 coupled together via a bus 212 over which the various elements can exchange data and information.

The receiver module 202, e.g., an OFDM receiver, is coupled to a receive antenna 216 via which the base station 200 receives uplink signals from wireless terminals. In some embodiments, the uplink signals include base station loading factor information corresponding to other base stations in the communication system, e.g., where wireless terminals connected to base station 200 and another base station (e.g., a neighboring base station) act as repeaters.

The transmitter module 204, e.g., an OFDM transmitter, is coupled to a transmit antenna 218 via which transmit antenna 218 the base station 200 transmits downlink signals to wireless terminals. The downlink signals include traffic channel signals and pilot channel signals, where the power budget of the traffic channel signals is controlled based on loading factor information corresponding to other base stations (e.g., neighboring base stations) and loading factor information corresponding to base station 200.

I/O interface 208 couples base station 200 to the internet and/or other network nodes, such as neighboring base stations. Loading factor information is exchanged between the base station 200 and other base stations (e.g., neighboring base stations) via the I/O interface 208. Thus, I/O interface 208 receives signals conveying base station loading factor information indicative of loading of at least one base station attachment point corresponding to at least one other base station (e.g., a neighboring base station).

Memory 210 includes routines 220 and data/information 222. The processor 206 (e.g., a CPU) executes the routines 220 and uses the data/information 222 in memory 210 to control the operation of the base station 220 and implement methods.

Routines 220 include communications routines 224 and base station control routines 226. Communications routines 224 implement the various communications protocols used by base station 200. The base station control routines 226 include a scheduler 228, a pilot channel signaling module 230, a traffic channel signaling module 232, a loading factor information recovery module 234, a downlink transmission power budget determination module 236, a loading factor determination module 238, a loading factor comparison module 240, and a loading factor tracking module 242. In some embodiments, at least one of loading factor comparison module 240 and loading factor tracking module 242 are included as part of downlink transmission power budget determination module 236.

A scheduler 228 schedules wireless terminals to downlink and uplink traffic channel segments. The pilot channel signaling module 230 controls the generation and transmission of pilot channel signals, e.g., known modulation symbols at predetermined power levels at predetermined locations in a recurring timing and frequency structure. In this exemplary embodiment, the pilot channel signals corresponding to the base station attachment points are transmitted at the same transmission power level per tone regardless of the downlink loading conditions of the base station 200 or neighboring base stations. The traffic channel signaling module 232 controls the generation and transmission of traffic channel segment signals, such as downlink traffic channel segment signals. For downlink traffic channels, the total power budget associated with a base station 200 attachment point is dynamically adjusted in response to the determination by downlink transmission power budget determination module 236. Individual subchannels within a downlink traffic channel may be, and sometimes are, transmitted at different power levels.

The loading factor information recovery module 234 recovers loading factor information for base station attachment points corresponding to other base stations (e.g., neighboring base stations) from the received signal. For example, the loading factor information recovery module 234 obtains (recovered BS 2LF (t1)248, recovered BS 2LF (tn)250, recovered BS N LF (t1)256, recovered BS N LF (tn)258) from the received signals (received BS 2 signal (1)244, received BS 2 signal (N)246, received BS N signal (1)252, received BS N signal (N)254), respectively. The loading factor information in various embodiments is about the downlink transmission loading of the base station attachment point, e.g., the downlink traffic channel loading of the base station attachment point.

Downlink transmission power budget determination module 236 determines a downlink transmission power budget for one or more attachment points of base station 200 based on the recovered loading factor information corresponding to at least one other base station, such as one other neighboring base station. In various embodiments, the determined power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data traffic channel. In some such embodiments, a portion of the determined power budget for the pilot channel is independent of the loading factor information, and a portion of the power budget corresponding to the data traffic channel depends on the base station loading factor information of other base stations (e.g., neighboring base stations) and the loading factor information of base station 200. For example, pilot channel signals may be transmitted at a per tone power level that is invariant to loading, while traffic channel signal transmission power levels may be varied with a determined loading factor of a base station 200 attachment point and a received loading factor corresponding to an attachment point of a neighboring base station. The results of the loading factor comparison module 240 may be used as input by the determination module 236. The determined transmission power budget (time T1)264 and the determined transmission power budget (time Tn)270 are outputs taken from the determination module 236.

For each attachment point of base station 200, loading factor determination module 238 determines a loading factor corresponding to the attachment point of base station 200. The determined base station loading factor (time t1)260 and the determined base station loading factor (time tn)262 represent the output of the determination module 236 at different times corresponding to the same base station 200 attachment point.

The loading factor comparison module 240 compares the determined loading factor corresponding to the attachment point of the base station 200 with the recovered loading factor corresponding to the attachment point of another base station (e.g., a neighboring base station).

In some embodiments, when loading factor comparison module 240 determines that the loading of the attachment points of other base stations (e.g., neighboring base stations) involved in the comparison is greater than the loading of the attachment point of base station 200, downlink transmission power budget determination module 236 determines the power budget to correspond to a first value indicative of the budget; and, when loading factor comparison module 240 determines that the loading of the attachment points of other base stations (e.g., neighboring base stations) involved in the comparison is less than the loading of the attachment point of base station 200, downlink transmission power budget determination module 236 determines the power budget to correspond to a second value indicating a power budget greater than the power budget indicated by the first value.

In some embodiments, a highly loaded base station sends its loading factor to a neighboring base station, expecting that the base station receiving the loading factor will have lower loading and will reduce its transmission power budget. This will then reduce the interference experienced by the highly loaded base station and allow the throughput of the highly loaded base station to increase.

The loading factor tracking module 242 tracks changes in loading factors of base station attachment points, e.g., attachment points corresponding to base station 200 and attachment points corresponding to other base stations, e.g., neighboring base stations. The detected changes identified by loading factor tracking module 242 are used by downlink transmission power budget determination module 236 to determine the power budget of the base station attachment point of base station 200. In some embodiments, downlink transmission power determination module 236 decreases a current power budget of an attachment point of base station 200 in response to a detected increase in loading of other base stations (e.g., neighboring base stations), and downlink transmission power determination module 236 increases the current power budget in response to a detected decrease in loading of other base stations (e.g., neighboring base stations). In some embodiments, the downlink transmission power determination module 236 increases the current power budget of the attachment point of the base station 200 in response to a detected increase in load of the attachment point of the base station 200, and the downlink transmission power determination module 236 decreases the current power budget in response to a detected decrease in load of the attachment point of the base station 200.

Data/information 222 includes received signals conveying loading factor information corresponding to a plurality of base stations over time ((received base station 2 signal (1) 244.. times, received base station 2 signal (N)246),. times., (received base station N signal (1) 252.. times, received base station N signal (N) 254)). In some embodiments, the received signal conveying loading factor information has been conveyed via the I/O interface 208 via a backhaul network. In some embodiments, the received signal has been received by receiver 202, e.g., where a wireless terminal coupled to two base stations relays the information. Data/information 210 also includes recovered base station 2 loading factor information (recovered BS 2 loading factors (t1) 248. ·, recovered BS 2 loading factors (tn)250) representing base station 2 loading at different times, recovered base station N loading factor information (recovered BS N loading factors (t1) 256. ·, recovered BS N loading factors (tn)258) representing base station N loading at different times, and determined BS 200 loading factor information (determined BS loading factors (t1) 260.., determined BS loading factors (tn)262) representing base station 200 loading at different times.

Data/information 222 also includes determined downlink power budget information (determined downlink transmission power budget (T1)264,. determined downlink transmission power budget (Tn)270) for BS 200 over time. Determined downlink transmission power budget information 264 includes pilot channel budget information 266 and determined downlink traffic channel budget information (T1)268, and determined downlink transmission power budget (Tn)270 includes pilot channel power budget information 266 and determined downlink traffic channel power budget (Tn) 272. In this exemplary embodiment, the pilot channel signal transmission power level does not change with load conditions; however, the downlink traffic channel power budget may (and sometimes does) change with, for example, changes in loading conditions and/or load conditions of neighboring base stations and/or base station 200.

The data/information 222 also includes comparison criteria 274 to modify the power budget, the current number of users 276, the amount of backlogged downlink traffic information 278, and downlink channel condition information. The comparison criteria 274 for modifying the power budget include predetermined thresholds used by the loading factor comparison module 240, the loading factor tracking module 242, and/or the downlink transmission power budget determination module 236. The current number of users 276 includes information corresponding to, for example, the number of currently registered users, the number of active users, and/or the number of on state users at the base station 200 connection point. The backlog downlink traffic channel information volume 278 includes, for example, information identifying the number of MAC frames of downlink traffic to be transmitted corresponding to each current user of the base station 200, and information identifying the number of MAC frames of downlink traffic to be transmitted corresponding to the composite of registered users. Downlink channel condition information 280 includes, for example, channel condition measurement information, e.g., signal-to-noise ratio measurement information and/or signal-to-interference ratio measurement information, corresponding to a current user of base station 200. At least some of the current number of users information 276, the backlog downlink traffic channel information 278, and the downlink channel condition information 280 are used by the loading factor determination module 238 to determine loading factors corresponding to the base station 200 attachment point.

Fig. 3 is a diagram of an exemplary wireless terminal 300, such as a mobile node, in accordance with various embodiments. Exemplary wireless terminal 300 may be any of the exemplary wireless terminals of fig. 1 or 4 or 5 or 6. The exemplary wireless terminal 300 includes a first receiver module 302, a first transmitter module 304, a processor 306, I/O devices 308, and memory 310 coupled together via a bus 312 over which the various elements may exchange data information. In some embodiments, the wireless terminal 300 also includes a second receiver module 318 and a second transmitter module 320 that are also coupled to the bus 312.

A first receiver module 302, e.g., an OFDM receiver, is coupled to a receive antenna 314, via which receive antenna 314 the wireless terminal 300 receives downlink signals from base stations. The downlink signals include assignment signals (e.g., downlink traffic channel segment assignment signals), downlink traffic channel segment signals, requests for wireless terminals to relay base station load information, commands for wireless terminals to relay base station load information and/or base station attachment point load information.

A first transmitter module 304, e.g., an OFDM transmitter, is coupled to a transmit antenna 316, via which transmit antenna 316 the wireless terminal 300 transmits uplink signals to the base station. In some embodiments, the receiver module 302 uses the same antenna as the transmitter module 304, e.g., in combination with a duplex module. The uplink signals include dedicated control channel reports (e.g., SNR reports), uplink traffic channel segment signals, access signals, power control signals, timing control signals, and handoff signals. The uplink signal also includes messages conveying loading factor information corresponding to a base station attachment point, e.g., where the wireless terminal is acting as a repeater between two adjacent base stations.

A second receiver module 318, such as an OFDM receiver, is coupled to receive antenna 322, via which receive antenna 322 the wireless terminal 300 receives downlink signals from the base station. The downlink signals include assignment signals (e.g., downlink traffic channel segment assignment signals), downlink traffic channel segment signals, requests for wireless terminals to relay base station load information, commands for wireless terminals to relay base station load information and/or base station attachment point load information.

A second transmitter module 320, e.g., an OFDM transmitter, is coupled to transmit antenna 324, via which transmit antenna 324 the wireless terminal 300 transmits uplink signals to the base station. In some embodiments, the receiver module 318 uses the same antenna as the transmitter module 324, e.g., in conjunction with a duplex module. The uplink signals include dedicated control channel reports (e.g., SNR reports), uplink traffic channel segment signals, access signals, power control signals, timing control signals, and handoff signals. The uplink signal also includes messages conveying loading information (e.g., downlink loading factor) corresponding to the base station attachment point, e.g., where the wireless terminal acts as a repeater between two base stations.

I/O devices 308 (e.g., keypad, keyboard, microphone, switches, display, speaker, etc.) allow a user of WT 300 to input data/information and access output data/information. The input device 308 also allows a user to control at least some functions of the wireless terminal, such as initiating a communication session with a peer node.

Memory 310 includes routines 326 and data/information 328. The processor 306, e.g., a CPU, executes the routines 326 and uses the data/information 328 in memory 310 to control the operation of the wireless terminal 300 and implement method steps. Routines 326 include communications routines 330 and base station control routines 332. The communications routine 330 implements the various communications protocols used by the wireless terminal 300. Base station control routines 332 include a loading factor relay request/command monitoring module 334, a loading factor recovery module 336, and a loading factor relay module 338.

Loading factor request/command monitoring module 334 monitors received downlink signaling for requests and/or commands directed to wireless terminal 300 instructing wireless terminal 300 to receive base station loading factor information (e.g., downlink traffic channel base station loading information) corresponding to one or more attachment points from a first base station and to relay the loading factor information to a second base station. In some embodiments, the load factor relay request/command monitoring module 334 is used when the wireless terminal 300 is in a wireless terminal mode of operation in which the wireless terminal supports two communication links to two different base station attachment points simultaneously. For example, WT 300 may be in a multi-connection mode of operation, currently coupled to a first base station via a receiver/transmitter module pair (302/304) and simultaneously coupled to a second base station via a receiver/transmitter module pair (318/320), and monitoring module 334 detects a signal requesting or instructing wireless terminal 300 to communicate downlink load information regarding the first base station attachment point to the second base station. In some embodiments, if the wireless terminal receives a request to transmit loading factor information and the wireless terminal is not in multi-connection mode, the wireless terminal may transition to multi-connection mode in response to the received request/command to transmit loading factor information.

A loading factor recovery module 336 responsive to a request or command detected by module 334 recovers loading information, e.g., downlink base station attachment point loading information, from the received downlink signal. Loading factor relay module 338, responsive to loading factor recovery module 336, generates a message conveying recovered loading factor information, which is communicated to another base station (e.g., a neighboring base station) via uplink signaling. The loading factor relay module 336 also controls the transmission of the generated relay messages.

Data/information 328 includes received relay loading factor information request/command 340, received base station loading factor information 342, generated base station loading factor message information 344, system base station information 346, and wireless terminal operating mode information 348. The received request/command to relay base station loading factor information 340 includes a received request and/or command to the wireless terminal 300 to act as a relay and communicate loading factor information between base stations. In some embodiments, the request identifies a destination base station. In some embodiments, the wireless terminal uses the stored system base station information 346 to determine the relevant destination base station (e.g., neighboring base station) that may be affected (e.g., interfered) by downlink signaling from the source base station attachment point. Received base station loading factor information 342 (e.g., base station attachment point loading factor corresponding to downlink traffic channel loading) is the output of the recovery module 336 and the input of the loading factor relay module 338. The generated base station loading factor relay message is the output of the loading factor relay module 338 and is used as an input to a wireless transmitter module, such as module 304 or module 320. System base station information 346 includes information corresponding to a plurality of base stations in a wireless communication system (base station 1 information 350. Base station 1 information 350 includes information corresponding to each of the base station 1's attachment points, such as downlink carrier information, downlink tone block information, uplink carrier information, channel structure information, tone hopping information, power level information, message structure information, cycle timing structure information, and so forth. WT operating mode information 348 includes information identifying whether wireless terminal 300 is in a single connection operating mode or a multiple connection operating mode.

Fig. 4 is a diagram of a flow chart 400 of an exemplary method of operating a first base station in a multiple access wireless communication system including multiple base stations, in accordance with various embodiments. Each base station in an exemplary communication system includes at least one base station attachment point through which wireless terminals (e.g., mobile nodes) in the vicinity of the base station may connect to the network. A base station may include one or more sectors. In this exemplary embodiment, a base station attachment point corresponds to a base station sector, uplink carrier, uplink OFDM tone block, downlink carrier, and downlink OFDM tone block.

Operation begins at step 402, where the first base station is powered on and initialized, and proceeds to step 404. At step 404, the first base station receives second base station loading factor information indicative of the loading of a second base station attachment point corresponding to a second base station. The second base station may be, and sometimes is, adjacent to the first base station. Exemplary loading information for a base station includes the number of active terminals connected, the quality of service (QoS) profile of the terminals (e.g., the number of high QoS value terminals versus the number of low QoS value terminals), the QoS profile of the traffic associated with the terminals (e.g., the amount of audio or video traffic versus the amount of best effort data traffic), and the radio link resources (e.g., power and bandwidth) needed to support the traffic needed by the connected active terminals. For example, as the base station services increased voice traffic, the load may increase. Furthermore, even if the base station serves the same traffic volume according to the number of bits per second, the load may be different if most of the connected terminals are farther from the base station than if most of the connected terminals are nearby. The reason is that the radio link resources (in particular, power) required to support the traffic are different. Operation proceeds from step 404 to step 406.

In step 406, the first base station determines a downlink transmission power budget based on additional loading factor information corresponding to another base station attachment point, the other base station attachment point being an attachment point for the first base station. For example, another attachment point of the first base station and a second attachment point of the second base station may correspond to neighboring sectors using the same downlink carrier frequency and the same downlink tone block, and the determined downlink transmission power budget may correspond to another base station attachment point of the first base station. In some embodiments, the determined downlink transmission power budget is for a set of downlink communication channels including at least a pilot channel and a data traffic channel. In some such embodiments, a first portion of the determined power budget (the first portion allocated for pilot channels) is independent of the first loading factor information and second loading factor information, and a second portion of the determined power budget (the second portion allocated to correspond to data traffic channels) is dependent on second base station loading factor information and additional loading factor information. For example, a pilot channel signal corresponding to an additional attachment point of the first base station is broadcast at a first predetermined transmission power level independent of the loading conditions of the second loading factor information and the additional loading factor information; however, traffic channel signals corresponding to additional attachment points of the first base station are transmitted at power levels that are a function of the second loading factor information and the additional loading factor information. Step 406 includes sub-steps 408, 410, 412, 414, 416, and 418.

In sub-step 408, the first base station compares said additional loading factor information of said first base station with said second base station loading factor information. The compared loading factor information may refer to the downlink loading of the downlink, e.g., downlink traffic channel radio link resources. Operation proceeds from sub-step 408 to sub-step 410. In sub-step 410 the first base station determines whether the comparison of sub-step 408 indicates that the second base station load is greater than said first base station load. If the check of step 410 indicates that the second base station load is greater than the first base station load, then operation proceeds to step 412, where the base station determines that the power budget corresponds to a first value indicative of the budget; otherwise operation proceeds from substep 410 to substep 414.

In sub-step 414, the first base station determines whether the comparison of sub-step 408 indicates that the second base station load is less than the first base station load. If the check of step 414 indicates that the second base station load is less than the first base station load, then operation proceeds to sub-step 416, where the base station determines that the power budget corresponds to a second value indicating a power budget that is greater than the power budget indicated by the first value; otherwise, operation proceeds from substep 414 to substep 418. In sub-step 418, the first base station determines that the power budget corresponds to a third value indicative of the budget. For example, the third value may indicate a power budget between the power budget indicated by the first value and the power budget indicated by the second value.

In some embodiments, the values of the base station loads compared in steps 410 and 420 are quantized into a representation of the actual load determination, and proceeding to step 418 may indicate that the first base station load quantization scale value is the same as the second base station load quantization scale value, indicating that the first base station and the second base station actual load determination are substantially the same.

In some embodiments, step 410 checks whether the second base station load is greater than the first base station load by a predetermined first amount, and step 410 checks whether the second base station load is greater than the first base station load by a predetermined second amount. Thus, if operation proceeds to step 418, the first base station load is indicated to be substantially the same as the second base station load.

Fig. 5 is a diagram of a flow chart 500 of an exemplary method of operating a first base station in a multiple access wireless communication system including multiple base stations, in accordance with various embodiments. Each base station in the exemplary communication system includes at least one base station attachment point through which wireless terminals (e.g., mobile nodes) in the vicinity of the base station may connect to a network. A base station may include one or more sectors. In this exemplary embodiment, a base station attachment point corresponds to a base station sector, uplink carrier, uplink OFDM tone block, downlink carrier, and downlink OFDM tone block.

Operation begins at step 502 where the first base station is powered on and initialized, and proceeds to step 504. At step 504, the first base station receives second base station loading factor information indicative of loading of a second base station attachment point corresponding to a second base station. The second base station may be, and sometimes is, adjacent to the first base station. Operation proceeds from step 504 to step 506.

At step 506, the first base station determines a downlink transmission power budget based on additional loading factor information corresponding to another base station attachment point, the other base station attachment point being the first base station's attachment point. For example, another attachment point of the first base station and a second attachment point of the second base station may correspond to neighboring sectors using the same downlink carrier frequency and the same downlink tone block, and the determined downlink transmission power budget may correspond to another base station attachment point of the first base station. In some embodiments, the determined downlink transmission power budget is for a set of downlink communication channels including at least a pilot channel and a data traffic channel. In some such embodiments, a first portion of the determined power budget (the first portion allocated for the pilot channel) is independent of the first loading factor information and the second loading factor information, and a second portion of the determined power budget (the second portion allocated to correspond to the data traffic channel) is dependent on the second base station loading factor information and the additional loading factor information. For example, pilot channel signals corresponding to the additional attachment points of the first base station are broadcast at a first predetermined transmission power level independent of loading conditions of the second loading factor information and the additional loading factor information; however, traffic channel signals corresponding to the additional attachment point of the first base station are transmitted at a power level that is a function of the second loading factor information and the additional loading factor information. Step 506 includes sub-steps 508, 510, 512, 514 and 516.

In sub-step 508, the first base station compares the current second base station loading factor information with previously stored second base station loading factor information. The compared loading factor information may refer to the downlink loading of the downlink, e.g., downlink traffic channel radio link resources. Operation proceeds from sub-step 508 to sub-step 510. In sub-step 510 the first base station determines whether the comparison of sub-step 508 indicates an increase, a decrease or no change in the load of said second base station. If the determination of step 510 is that the load of the second attachment point of the second base station has increased, then operation proceeds to step 512 where the first base station decreases the downlink transmission power budget. If the determination of step 510 is that the load of the second base station has not changed, then operation proceeds from step 510 to step 516, where the first base station does not change the downlink transmission power budget at step 516. If the determination of step 510 is that the load of the second attachment point of the second base station has decreased, then operation proceeds to step 514 where the first base station increases the downlink transmission power budget.

Fig. 6 is a diagram of a flow chart 600 of an exemplary method of operating a first base station in a multiple access wireless communication system including multiple base stations, in accordance with various embodiments. Each base station in the exemplary communication system includes at least one base station attachment point through which wireless terminals (e.g., mobile nodes) in the vicinity of the base station may connect to a network. A base station may include one or more sectors. In this exemplary embodiment, a base station attachment point corresponds to a base station sector, uplink carrier, uplink OFDM tone block, downlink carrier, and downlink OFDM tone block.

Operation begins at step 602, where the first base station is powered on and initialized, and proceeds to step 604. At step 604, the first base station receives second base station loading factor information indicative of the loading of a second base station attachment point corresponding to a second base station. The second base station may be, and sometimes is, adjacent to the first base station. Operation proceeds from step 604 to step 606.

In step 606, the first base station determines a downlink transmission power budget based on additional loading factor information corresponding to another base station attachment point, the other base station attachment point being the first base station's attachment point. For example, another attachment point of the first base station and a second attachment point of the second base station may correspond to neighboring sectors using the same downlink carrier frequency and the same downlink tone block, and the determined downlink transmission power budget may correspond to another base station attachment point of the first base station. In some embodiments, the determined downlink transmission power budget is for a set of downlink communication channels including at least a pilot channel and a data traffic channel. In some such embodiments, a first portion of the determined power budget (the first portion allocated for pilot channels) is independent of the first loading factor information and the second loading factor information, and a second portion of the determined power budget (the second portion allocated to correspond to data traffic channels) is dependent on second base station loading factor information and additional loading factor information. For example, a pilot channel signal corresponding to an additional attachment point of the first base station is broadcast at a first predetermined transmission power level independent of the loading conditions of the second loading factor information and the additional loading factor information; however, traffic channel signals corresponding to the additional attachment point of the first base station are transmitted at a power level that is a function of the second loading factor information and the additional loading factor information. Step 606 includes sub-steps 608, 610, 612, 614, and 616.

In sub-step 608, the first base station compares the current first base station loading factor information with previously stored first base station loading factor information. The compared loading factor information may refer to the downlink loading of the downlink, e.g., downlink traffic channel radio link resources. Operation proceeds from sub-step 608 to sub-step 610. In sub-step 610 the first base station determines whether the comparison of sub-step 608 indicates an increase, a decrease or no change in the load of said first base station. If the determination of step 610 is that the load of the additional attachment point of the first base station has increased, then operation proceeds to step 612 where the first base station increases the downlink transmission power budget. If the determination of step 610 is that there is no change in the load of the first base station, then operation proceeds from step 610 to step 616 where the first base station does not change the downlink transmission power budget. If the determination of step 610 is that the load of the first base station has decreased, then operation proceeds to step 614, where the first base station decreases the downlink transmission power budget.

Fig. 7 is a diagram 1000 illustrating features of various embodiments, wherein a base station in a wireless communication system including a plurality of base stations receives loading factor information corresponding to another base station and determines a downlink transmission power budget based on the received base station loading factor information. Diagram 1000 includes an exemplary diagram 1002 that includes a base station 11050 and a base station 21052 coupled together via a network link 1068. Base station 11050 is coupled via wireless links to a plurality of wireless terminals (WT 11054, WT 21056, WT 31058, WT 41060). Base station 21052 is coupled via wireless links to a plurality of wireless terminals (WT1 '1062, WT 4' 1064). BS 11050 has calculated a loading factor 1071 corresponding to its current downlink traffic channel loading. BS 21052 has calculated a loading factor 1072 corresponding to its current downlink traffic channel loading. BS 2 sends a message 1074 conveying its loading factor 1072 via backhaul network link 1068. BS 11052 receives loading factor message 1074, recovers the loading factor corresponding to BS 21072 and compares loading factor 1072 with its own loading factor 1070. BS 1 determines that loading factor 1072 of BS 2 is less than its own loading factor 1070 and thus sets its downlink transmission power budget to a first level. Diagram 1006 of diagram 1000 illustrates the downlink power budget for BS 1 corresponding to the example of diagram 1002. In diagram 1006, the height of arrow 1010 indicates the BS 1 downlink power budget for the determined condition where the loading factor of base station 2 is less than the loading factor of base station 1. The downlink power budget 1010 can be divided into a first portion 1012 associated with the downlink pilot channel, a second portion 1016 associated with the downlink traffic channel, and a third portion 1014 associated with other downlink channels.

Diagram 1000 also includes an exemplary diagram 1004 that includes base station 11050 and base station 21052 coupled together via a network link 1068. Base station 11050 is coupled via wireless links to a plurality of wireless terminals (WT 11054, WT 21056, WT 31058, WT 41060). At this point, base station 21052 is coupled via wireless links to a plurality of wireless terminals (WT1 ' 1062, WT4 ' 1064, WT 5 ' 1076, WT2 ' 1078, WT 6 ' 1080, WT 3 ' 1082, WT 7 ' 1084). BS 11050 has calculated a loading factor 1086 corresponding to its current downlink traffic channel loading. BS 21052 has calculated a loading factor 1088 corresponding to its current downlink traffic channel loading. BS 2 sends a message 1090 conveying its loading factor 1088 via backhaul network link 1068. BS 11052 receives loading factor message 1090, recovers loading factor 1088 corresponding to BS 2 and compares loading factor 1088 with its own loading factor 1086. BS 1 determines that loading factor 1088 of BS 2 is greater than its own loading factor 1086 and, therefore, sets its downlink transmission power budget to a second level 1018, which is less than first level 1010. Diagram 1008 of diagram 1000 illustrates the BS 1 downlink power budget corresponding to the example of diagram 1004. In diagram 1008, the height of arrow 1018 indicates the BS 1 downlink power budget for the determined condition where the loading factor of base station 2 is greater than the loading factor of base station 1. The downlink power budget 1018 can be divided into a first portion 1020 associated with the downlink pilot channel, a second portion 1026 associated with the downlink traffic channel, and a third portion 1024 associated with other downlink channels. In this example, note that the power levels 1012, 1020 associated with the pilot channels are the same regardless of the loading factor comparison determination; however, the downlink traffic channel power budget (1016, 1026) changes in response to different results from the load factor comparison.

Fig. 8 is a diagram 1100 illustrating features of various embodiments, wherein a base station in a wireless communication system including a plurality of base stations receives loading factor information corresponding to another base station and determines a downlink transmission power budget as a function of the received base station loading factor information. Diagram 1000 includes an exemplary diagram 1102 that includes a base station 11150 and a base station 21152 coupled together via a network link 1170. The base station 11150 is coupled to a plurality of wireless terminals (WT 11154, WT 21156, WT 31158, WT 41160) via wireless links. Base station 21152 is coupled to a plurality of wireless terminals (WT1 '1162, WT 2' 1164, WT 3 '1166, WT 4' 1168) via wireless links. BS 11150 has calculated a loading factor 1172 corresponding to its current downlink traffic channel loading. BS 21152 has calculated a loading factor 1174 corresponding to its current downlink traffic channel loading. BS 2 sends its Load Factor (LF) over backhaul network link 1170_BS2(t1)) 1174. BS 11150 receives the loading factor message 1176, recovers the loading factor 1174 corresponding to BS 2 and compares the loading factor 1174 with its own loading factor 1172. In this example, BS 1 determines that the loading factor 1174 of BS 2 is the same as its own loading factor 1172, and for purposes of illustration, it is assumed that both base stations are stable at these levels, and thus base station 1 no longer adjusts its power budget to be set to level 1114. Diagram 1108 of diagram 1100Indicating the downlink power budget for BS 1 corresponding to the example of diagram 1102. In diagram 1108, the height of arrow 1114 indicates the BS 1 downlink power budget. Downlink power budget 1114 may be divided into a first portion 1116 associated with a downlink pilot channel, a second portion 1120 associated with a downlink traffic channel, and a third portion 1118 associated with other downlink channels.

Diagram 1100 also includes an exemplary diagram 1104 that includes a base station 11150 and a base station 21152 coupled together via a network link 1170. The base station 11150 is coupled to a plurality of wireless terminals (WT 11154, WT 21156, WT 31158, WT 41160) via wireless links. At this point, the base station 21152 is coupled via wireless links to a plurality of wireless terminals (WT1 ' 1162, WT2 ' 1164, WT 3 ' 1166, WT4 ' 1168, WT 5 ' 1178, WT 6 ' 1180, WT 7 ' 1182). BS 11150 has calculated a loading factor 1172 corresponding to its current downlink traffic channel loading. The BS 21152 has calculated a Loading Factor (LF) corresponding to its current downlink traffic channel loading_BS2(t2)) 1184. BS 2 sends a message 1186 conveying its load factor 1184 via backhaul network link 1170. BS 11150 receives loading factor message 1186, recovers loading factor 1184 corresponding to BS 2 and compares loading factor 1184 with previously stored Loading Factor (LF) corresponding to BS 2_BS2(t1)) 1174. BS 1 determines that the current loading factor 1184 of BS 2 is greater than the previous loading factor 1174 of BS 2 and therefore reduces its downlink transmission power budget to level 1122. Diagram 1110 of diagram 1100 illustrates the downlink power budget for BS 1 corresponding to the example of diagram 1104. In diagram 1100, the height of arrow 1122 indicates the downlink power budget adjusted by BS 1 for a determined condition in which the current loading factor of base station 2 is greater than the previous loading factor of base station 2. The downlink power budget 1122 can be divided into a first portion 1124 associated with downlink pilot channels, a second portion 1128 associated with downlink traffic channels, and a third portion 1126 associated with other downlink channels. In this example, note that regardless of the loading factor comparison determination, the power levels 1116, 1124 associated with the pilot channels are the same; however, the downlink traffic channel budget (1120, 112)8) Changes in response to different results from the load factor comparison tracking.

Diagram 1100 also includes an exemplary diagram 1106 that includes a base station 11150 and a base station 21152 coupled together via a network link 1170. The base station 11150 is coupled to a plurality of wireless terminals (WT 11154, WT 21156, WT 31158, WT 41160) via wireless links. At this point, base station 21152 is coupled via wireless links to a plurality of wireless terminals (WT1 '1162, WT 4' 1168). BS 11150 has calculated a loading factor 1172 corresponding to its current downlink traffic channel loading. The BS 21152 has calculated a Loading Factor (LF) corresponding to its current downlink traffic channel loading_BS2(t3)) 1188. BS 2 sends a message 1190 conveying its loading factor 1188 via backhaul network link 1170. BS 11150 receives loading factor message 1190, recovers loading factor 1188 corresponding to BS 2 and compares loading factor 1188 with a previously stored Loading Factor (LF) corresponding to BS 2_BS2(t2)) 1184. BS 1 determines that the current loading factor 1188 of BS 2 is less than the previous loading factor 1184 of BS 2 and therefore increases its downlink transmission power budget to level 1130. Diagram 1112 of diagram 1100 illustrates the downlink power budget for BS 1 corresponding to the example of diagram 1106. In diagram 1112, the height of arrow 1130 indicates the downlink power budget adjusted by BS 1 for the determined condition where the current loading factor of base station 2 is less than the previous loading factor of base station 2. Downlink power budget 1130 can be divided into a first portion 1132 associated with downlink pilot channels, a second portion 1136 associated with downlink traffic channels, and a third portion 1134 associated with other downlink channels. In this example, it should be noted that regardless of the loading factor comparison determination, the power levels 1124, 1132 associated with the pilot channels are the same; however, the downlink traffic channel power budget (1128, 1136) changes in response to different results from the comparative tracking of the loading factor.

FIG. 9 is a diagram 1200 used to illustrate features of various embodiments, where a base station in a wireless communication system including multiple base stations receives loading factor information corresponding to another base station and based on base station loading factor informationA downlink transmission power budget is determined. Diagram 1200 includes an exemplary diagram 1202 that includes a base station 11250 and a base station 21252 coupled together via a network link 1270. Base station 11250 is coupled via wireless links to a plurality of wireless terminals (WT 11254, WT 21256, WT 31258, WT 41260). Base station 21252 is coupled to a plurality of wireless terminals (WT1 '1262, WT 2' 1264, WT 3 '1266, WT 4' 1268) via wireless links. BS 11250 has calculated a Load Factor (LF) corresponding to its current downlink traffic channel load_BS1(t1)) 1272. BS 21252 has calculated a loading factor 1274 corresponding to its current downlink traffic channel loading. BS 2 sends its Load Factor (LF) over backhaul network link 1270_BS2)1274, and message 1276. BS 11250 receives loading factor message 1276, recovers loading factor 1274 corresponding to BS 2 and compares loading factor 1274 to its own loading factor 1272. In this example, BS 1 determines that loading factor 1274 of BS 2 is the same as its own loading factor 1272, and for purposes of illustration, it will be assumed that both base stations are stable at these levels, and thus base station 1 no longer adjusts its power budget that is set to level 1214. Diagram 1208 of diagram 1200 illustrates the BS 1 downlink power budget corresponding to the example of diagram 1202. In diagram 1208, the height of arrow 1214 indicates the BS 1 downlink power budget. The downlink power budget 1214 can be divided into a first portion 1216 associated with the downlink pilot channel, a second portion 1220 associated with the downlink traffic channel, and a third portion 1218 associated with other downlink channels.

Diagram 1200 also includes an exemplary diagram 1204 that includes a base station 11250 and a base station 21252 coupled together via a network link 1270. At this point, base station 11250 is coupled via wireless links to a plurality of wireless terminals (WT 11254, WT 21256, WT 31258, WT 41260, WT 51278, WT 61280, WT 71282). At this point, base station 21252 is coupled via wireless links to a plurality of wireless terminals (WT1 '1262, WT 2' 1264, WT 3 '1266, WT 4' 1268). BS 11250 has calculated a Load Factor (LF) corresponding to its current downlink traffic channel load_BS1(t2)) 1272. BS 21252 has calculated a value corresponding to its current downLoad Factor (LF) for uplink traffic channel loading_BS2)1274. BS 2 sends a message 1276 conveying its loading factor 1274 via backhaul network link 1270. BS 11250 receives loading factor message 1276, restores loading factor 1274 corresponding to BS 2 and recognizes that the loading factor corresponding to BS 2 remains unchanged. BS 11250 compares its current load factor 1284 with the previously stored Load Factor (LF) corresponding to BS 1_BS1(t1)) 1272. BS 1 determines that the current loading factor 1284 of BS 1 is greater than the previous loading factor 1272 of BS 1 and thus increases its downlink transmission power budget to level 1222. Diagram 1210 of diagram 1200 illustrates the downlink power budget for BS 1 corresponding to the example of diagram 1204. In diagram 1210, the height of arrow 1222 indicates the BS 1 adjusted downlink power budget for a determined condition where the current loading factor of base station 1 is greater than the previous loading factor of base station 1. Downlink power budget 1222 can be divided into a first portion 1224 associated with downlink pilot channels, a second portion 1228 associated with downlink traffic channels, and a third portion 1226 associated with other downlink channels. In this example, it should be noted that the power levels 1216, 1224 associated with the pilot channels are the same regardless of the loading factor comparison determination; however, the downlink traffic channel power budget (1220, 1228) changes in response to different results from the load factor comparison.

Diagram 1200 also includes an exemplary diagram 1206 including a base station 11250 and a base station 21252 coupled together via a network link 1270. At this point, base station 11250 is coupled via wireless links to multiple wireless terminals (WT 31258, WT 41260). At this point, base station 21252 is coupled via wireless links to a plurality of wireless terminals (WT1 '1262, WT 2' 1264, WT 3 '1266, WT 4' 1268). BS 11250 has calculated a Load Factor (LF) corresponding to its current downlink traffic channel load_BS1(t3) 1286. BS 21252 has calculated a Loading Factor (LF) corresponding to its current downlink traffic channel loading_BS2)1274. BS 2 sends a message 1276 conveying its loading factor 1274 via backhaul network link 1270. BS 11250 receives load factor message 1276, recovers load factor 1274 corresponding to BS 2 and recognizesThe load factor to the corresponding BS 2 remains unchanged. BS 1 compares its current loading factor 1286 with a previously stored Loading Factor (LF) corresponding to BS 1_BS1(t2)) 1284. BS 1 determines that the current loading factor 1286 of BS 1 is less than the previous loading factor 1284 of BS 1 and therefore reduces its downlink transmission power budget to level 1230. Diagram 1212 of diagram 1200 illustrates the BS 1 downlink power budget corresponding to the example of diagram 1206. In diagram 1212, the height of arrow 1230 indicates the BS 1 adjusted downlink power budget for the determined condition where the current loading factor of base station 1 is less than the previous loading factor of base station 1. The downlink power budget 1230 can be divided into a first portion 1232 associated with the downlink pilot channel, a second portion 1236 associated with the downlink traffic channel, and a third portion 1234 associated with the other downlink channels. In this example, note that the power levels 1224, 1232 associated with the pilot channels are the same regardless of the loading factor comparison determination; however, the downlink traffic channel power budget (1228, 1236) changes in response to different results from the load factor comparison.

Fig. 10, which includes a combination of fig. 10A and 10B, is a diagram of a flowchart 2000 of an exemplary method of operating a base station in accordance with various embodiments. This exemplary base station (e.g., base station 200 of fig. 2) may be a base station in a multiple access wireless communication system that includes multiple base stations, each including at least one base station attachment point. Operation begins at step 2002 where the base station is powered on and initialized. Operation proceeds from start step 2002 via connecting node a 2032 to step 2004, step 2010, step 2020, and step 2034.

In step 2004, which is performed on a recurring basis, the base station determines the downlink load for each base station attachment point. The output of step 2004 is base station 1 downlink loading factor 2006. ·, base station 1 attachment point n downlink loading factor 2008. Information (2006...., 2008) is input in step 2020 and step 2034.

In step 2010, the base station receives downlink loading factor information corresponding to other base stations (e.g., neighboring base stations). The reception may be via an interface to a backhaul network and/or via a wireless receiver, e.g., by a wireless terminal simultaneously connecting to the base station and another base station acting as a relay. The receiving may be performed on a recurring basis in response to a request and/or in response to a decision to communicate its downlink load information by another base station. Information corresponding to various attachment points for one or more base stations is the output of step 2010 (base station 2 attachment point 1 downlink loading factor 2012,.. solbase station 2 attachment point m downlink loading factor 2014, soln attachment point 1 downlink loading factor 2016, soln attachment point p downlink loading factor 2018). Information (2012, 2014, 2016, 2018) is input in step 2020.

Step 2020 is performed for each attachment point of the base station on an ongoing basis. In step 2020, the base station determines a downlink transmission power budget based on loading factor information corresponding to one or more other base stations (e.g., neighboring base stations). In some embodiments, the determined downlink transmission power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data channel, and the pilot channel transmission power level (e.g., power per tone of the pilot channel) is independent of loading information, while the portion of the determined downlink power budget corresponding to a traffic channel depends on loading information of a base station attachment point to which the budget corresponds and loading of one or more neighboring points of one or more neighboring base stations. Step 2020 includes sub-steps 2022, 2024, 2026, and 2028. In sub-step 2022, the base station compares the current load of the considered base station attachment point with the load of one or more attachment points of one or more neighboring base stations that may interfere with the considered attachment point. In sub-step 2024, the base station compares the current load of the considered base station attachment point with the previous load of the considered base station attachment point. In sub-step 2026, the base station compares the current load of the potentially interfering neighboring base station attachment point with the previous load of the same potentially interfering neighboring base station attachment point. Sub-step 2026 may be performed for a plurality of different potentially interfering neighboring base station attachment points.

Operation proceeds from sub-steps 2022, 2024, and 2026 to sub-step 2028. In sub-step 2028, the base station adjusts the base station attachment point downlink transmission power budget as a function of changes in base station attachment point loading over time, changes in adjacent base station attachment point loading over time, comparison of the loading of the base station attachment point under consideration with the loading of one or more attachment points adjacent the base station, the current downlink transmission power budget, the previous downlink transmission power budget, and the alternative possible downlink transmission power budget. Sub-step 2028 includes sub-step 2030. In sub-step 2030, the base station adjusts the base station attachment point downlink traffic channel power budget.

In some embodiments, determining a power budget for a base station attachment point comprises: determining that the power budget corresponds to a first value indicative of the budget when the comparison indicates that the load of the attachment points of other base stations (e.g., neighboring base stations) is greater than the load of the base station attachment point to which the budget applies; and determining that the power budget corresponds to a second value indicative of a power budget greater than the power budget indicated by the first value when the comparison indicates that the loading of other base stations (e.g., neighboring base stations) is less than the loading of the base station attachment point to which the budget applies.

In various embodiments, determining the power budget for a base station attachment point includes decreasing the current power budget in response to detecting an increase in loading of attachment points of other base stations (e.g., neighboring base stations). In some embodiments, determining the power budget for a base station attachment point comprises increasing the current power budget in response to detecting a decrease in attachment point loading of other base stations (e.g., neighboring base stations).

In various embodiments, determining the power budget for a base station attachment point comprises increasing the current power budget in response to detecting an increase in the attachment point load. In some embodiments, determining the power budget for a base station attachment point comprises reducing the current power budget in response to detecting a reduction in the attachment point load.

In some embodiments, for an attachment point, the base station supports multiple (e.g., two, three, or more) predetermined downlink transmission power budget alternative levels, and for a given time of the attachment point, the base station selects to use one of the possible alternative levels. Thus, a base station may dynamically vary its power budget between possible alternatives in response to load changes (including load changes of neighboring base stations). In some embodiments, a base station may communicate information identifying its selected downlink transmission power budget level to other base stations (e.g., neighboring base stations).

At step 2034, the base station generates a message conveying base station attachment point downlink load information. Base station attachment point loading information (BS 1 attachment point 1 downlink loading factor 2006. ·, base station 1 attachment point n downlink loading factor 2008) is the output of step 2034. Operation proceeds from step 2034 to step 2036. At step 2036, the base station transmits the message generated at step 2034 including the determined base station attachment point loading factor information directed to other one or more base stations (e.g., neighboring base stations). Transmissions directed to a neighboring base station may be via an interface to a backhaul network and/or via a wireless terminal coupled to the base station and the neighboring base station. The operations of steps 2034 and 2036 are performed on an ongoing basis, e.g., as part of a recurring timing structure, in response to requests from neighboring base stations and/or based on a decision by a base station to communicate its load information to one or more neighboring base stations. In some embodiments, the downlink loading factor of one of the base station attachment points is communicated to one or more selected neighboring base stations in response to the base station determining that its load has reached a high level and/or in response to a detected load change (a predetermined amount of change).

Although described in the context of an OFDM system, the methods and apparatus of various embodiments are applicable to a wide range of communication systems, including many non-OFDM and/or non-cellular systems.

In various embodiments, nodes described herein are implemented using one or more modules to perform steps corresponding to one or more methods, e.g., signal processing, beacon generation, beacon detection, beacon measurement, connection comparison, connection implementation. In some embodiments, various features are implemented using modules. The modules may be implemented using software, hardware, or a combination of software and hardware. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RAM, floppy disk, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods, e.g., within one or more nodes. Accordingly, various embodiments are directed to machine-readable media including machine executable instructions for causing a machine, such as a processor and associated hardware, to perform one or more of the steps of the above-described methods.

Numerous additional variations on the methods and apparatus described above will be apparent to those skilled in the art in view of the above description. Such variations are to be considered within the scope. The methods and apparatus of various embodiments may be used with CDMA, Orthogonal Frequency Division Multiplexing (OFDM), and/or various other types of communications techniques which may be used to provide wireless communications links between access nodes and mobile nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with mobile nodes using OFDM and/or CDMA. In various embodiments the mobile nodes are implemented as notebook computers, Personal Data Assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the methods of various embodiments.

Claims (35)

1. A method of operating a first base station in a multiple access wireless communication system comprising a plurality of base stations, each of the plurality of base stations comprising at least one base station attachment point, the method comprising:

receiving second base station loading factor information indicative of a second base station attachment point loading corresponding to a second base station; and

determining a downlink transmission power budget as a function of the received second base station loading factor information.

2. The method of claim 1, wherein determining a downlink transmission power budget is further performed as a function of additional loading factor information corresponding to another base station attachment point.

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

wherein the other base station connection point corresponds to the first base station, an

Wherein the determining a downlink transmission power budget includes comparing the additional loading factor information to the second base station loading factor information.

4. The method of claim 2, wherein the determined downlink transmission power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data traffic channel; and is

Wherein a portion of the determined downlink transmission power budget for the pilot channel is independent of the additional loading factor information and the second loading factor information, and wherein a portion of the determined downlink transmission power budget for the data traffic channel depends on the second base station loading factor information and the additional loading factor information.

5. The method of claim 3, wherein determining the power budget comprises:

determining that the power budget corresponds to a first value indicative of the budget when the comparison indicates that the second base station load is greater than the first base station load; and

determining that the power budget corresponds to a second value indicative of a power budget that is greater than the power budget indicated by the first value when the comparison indicates that the second base station load is less than the first base station load.

6. The method of claim 2, wherein determining the power budget comprises:

reducing a current power budget in response to detecting an increase in load of the second base station.

7. The method of claim 2, wherein determining the power budget comprises:

increasing a current power budget in response to detecting a decrease in the load of the second base station.

8. The method of claim 2, wherein determining the power budget comprises:

increasing a current power budget in response to detecting an increase in load of the first base station.

9. The method of claim 2, wherein determining the power budget comprises:

reducing a current power budget in response to detecting a reduction in load of the first base station.

10. A base station, comprising:

means for receiving base station loading factor information indicative of a loading of a base station attachment point corresponding to another base station; and

means for determining a downlink transmission power budget, wherein the means for determining a downlink transmission power budget determines the downlink transmission power budget as a function of the received base station loading factor information.

11. The base station of claim 10, wherein said means for determining a downlink transmission power budget determines the downlink transmission power budget as a function of additional loading factor information corresponding to additional base station attachment points.

12. The base station according to claim 11, wherein,

wherein the additional base station connection point corresponds to the base station, an

Wherein the means for determining a downlink transmission power budget comprises means for comparing the additional loading factor information with the other base station loading factor information.

13. The base station of claim 11, wherein the determined downlink transmission power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data traffic channel; and is

Wherein a portion of the determined power budget for the pilot channel is independent of the other loading factor information and the additional loading factor information, and wherein a portion of the determined downlink transmission power budget for the data traffic channel depends on the other base station loading factor information and the additional loading factor information.

14. The base station of claim 12, wherein said means for determining a downlink transmission power budget determines that said downlink transmission power budget corresponds to a first value indicative of said budget when said comparing indicates that said other base station load is greater than said base station load; and when the comparison indicates that the other base station load is less than the base station load, determining that the downlink transmission power budget corresponds to a second value indicating a power budget that is greater than the power budget indicated by the first value.

15. The base station of claim 11, wherein said means for determining a downlink transmission power budget decreases a current power budget in response to detecting an increase in loading of said other base stations.

16. The base station of claim 11, wherein the means for determining a downlink transmission power budget increases a current power budget in response to detecting a decrease in loading of the second base station.

17. The base station of claim 11, wherein said means for determining a downlink transmission power budget comprises means for tracking load changes of the base station, and wherein said means for determining a downlink transmission power budget increases a current power budget in response to detecting an increase in load of the base station.

18. The base station of claim 11, wherein said means for determining a downlink transmission power budget comprises means for tracking load changes of the base station, and wherein said means for determining a downlink transmission power budget decreases a current power budget in response to detecting a decrease in load of the base station.

19. A base station, comprising:

an interface for receiving a signal conveying base station loading factor information indicative of loading of at least one base station attachment point corresponding to at least one other base station;

a loading factor information recovery module for recovering loading factor information corresponding to at least one other base station from the received signal;

a downlink transmission power budget determination module, wherein the downlink transmission power budget determination module determines a downlink transmission power budget for an attachment point of at least one other base station as a function of the recovered loading factor information corresponding to the base station.

20. The base station of claim 19, further comprising:

a loading factor determination module for determining a loading factor corresponding to a connection point of the base station;

a loading factor comparison module for comparing the determined loading factor corresponding to the attachment point of the base station with a restored loading factor corresponding to an attachment point of another base station, and wherein the downlink transmission power budget determination module uses the results of the loading factor comparison module to determine the downlink power budget.

21. The base station of claim 19, wherein the determined power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data traffic channel; and is

Wherein a portion of the determined power budget for the pilot channel is independent of the other loading factor information and the additional loading factor information, and wherein a portion of the power budget for the data traffic channel depends on the other base station loading factor information and the additional loading factor information.

22. The base station of claim 21, wherein said downlink transmission power budget determination module determines that said power budget corresponds to a first value indicative of said budget when said loading factor comparison module determines that said other base station loading is greater than said base station loading; and when the loading factor comparison module indicates that the other base station loading is less than the base station loading, determining that the power budget corresponds to a second value indicating a power budget that is greater than the power budget indicated by the first value.

23. The base station of claim 21, further comprising:

a loading factor tracking module for tracking changes in loading factors of base station attachment points, and wherein the downlink transmission power budget determination module decreases a current power budget in response to detecting an increase in loading of one of the other base stations.

24. The base station of claim 21, further comprising:

a loading factor tracking module for tracking changes in loading factors of base station attachment points, and wherein the downlink transmission power budget determination module increases a current power budget in response to detecting a decrease in loading of one of the other base stations.

25. The base station of claim 21, further comprising:

a loading factor tracking module for tracking changes in loading factors of base station attachment points, and wherein the downlink transmission power budget determination module increases a current power budget in response to detecting an increase in loading of the base station's attachment point.

26. The base station of claim 21, further comprising:

a loading factor tracking module for tracking changes in loading factors of base station attachment points, and wherein the downlink transmission power budget determination module reduces a current power budget in response to detecting a decrease in loading of the base station's attachment point.

27. A computer readable medium embodying machine executable instructions for controlling a first base station to implement a method in a multiple access wireless communication system comprising a plurality of base stations, the method comprising:

receiving second base station loading factor information indicative of a loading of a second base station attachment point corresponding to a second base station; and

determining a downlink transmission power budget as a function of the received second base station loading factor information.

28. The computer readable medium of claim 27, further comprising machine executable instructions to determine the downlink transmission power budget as a function of additional loading factor information corresponding to another base station attachment point.

29. The computer-readable medium of claim 28, wherein the another base station attachment point corresponds to the first base station.

30. The computer-readable medium of claim 29, further comprising machine-executable instructions to:

comparing additional loading factor information with the second base station loading factor information as part of determining the downlink transmission power budget.

31. The computer-readable medium of claim 30, wherein the determined downlink transmission power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data traffic channel; and is

Wherein a portion of the determined downlink transmission power budget for the pilot channel is independent of the additional loading factor information and the second loading factor information, and wherein a portion of the determined downlink transmission power budget for the data traffic channel is dependent on the second base station loading factor information and the additional loading factor information.

32. A base station operable in a communication system, the base station comprising:

a processor configured to:

receiving second base station loading factor information indicative of a loading of a second base station attachment point corresponding to a second base station; and

determining a downlink transmission power budget as a function of the received second base station loading factor information.

33. The base station of claim 32, wherein the processor is further configured to:

determining the downlink transmission power budget as a function of additional loading factor information corresponding to another base station attachment point.

34. The base station according to claim 33, wherein,

wherein the other base station connection point corresponds to the first base station, an

Wherein the processor is further configured to determine the downlink transmission power budget by operations comprising comparing additional loading factor information with the second base station loading factor information.

35. The base station of claim 34, wherein said determined downlink transmission power budget is a power budget for a set of downlink communication channels including at least a pilot channel and a data traffic channel; and is

Wherein a portion of the determined downlink transmission power budget for the pilot channel is independent of the additional loading factor information and the second loading factor information, and wherein a portion of the determined downlink transmission power budget for the data traffic channel depends on the second base station loading factor information and the additional loading factor information.