CN1886971A - Access terminal identification management - Google Patents

Abstract

Access terminal identification management providing a minimum distance between subnets before reusing subnet identifiers. Mobility criteria evaluation determines when to reassign an access terminal identifier. In one embodiment, the mobility criteria is whether any member of the active set for the access terminal belongs to an originating subnet. In an alternate embodiment, the criteria is whether the access terminal has traveled more than a minimum distance from the originating subnet. When a mobility criteria is violated, the access network assigns a new identifier. In one embodiment, the access terminal identifier is a long code mask based on a subnet identifier. Identifier management applies when crossing sector boundaries in a cellular system, and serves to reduce the ambiguity of mapping CC values to full UATI values, and to avoid overlapping assignments.

Description

Access Terminal Identifier Management

Priority claims pursuant to 35 U.S.C. §119

This patent application claims priority to Provisional Application No. 60/524,598, filed November 24, 2003, entitled "ACCESSTERMINAL IDENTIFICATION MANAGEMENT," which is assigned to the applicant of the present invention, and is expressly incorporated herein by reference.

technical field

The present invention relates generally to communication systems, and more particularly to access terminal identifiers in communication systems.

Background technique

In a cellular radio communication system, a cell may include multiple sectors. Multiple cells can define a subnet. When a mobile station (MS) or access terminal (AT) initiates communication with a base station (BS) or access network (AN), the AT can be identified with a Universal Access Terminal Identifier (UATI). The UATI is specific to the subnet where the AT is at the beginning of the communication, that is, the subnet where the AT is when the connection is established. ATs initiating communications within a given subnet will each be assigned a full UATI with a common most significant bit (MSB). The MSB of the full UATI is the subnet identifier or "subnet ID". The least significant bit (LSB) of the complete UATI is unique to each AT. Thus, the MSB of the UATI identifies the subnet and the LSB of the UATI identifies the AT.

UATI is 128 bits and is unique in the world. In order to obtain short UTI-based identifiers that are locally unique, a subnet "color coding" scheme, referred to herein as "CC", assigns color codes to individual subnets. The CC is a locally unique 8-bit number and provides a mapping to the 104-bit MSB of the UATI within the same subnet. The 24-bit LSB and CC of UATI are used to generate a long mask (LCM) for each AT. In fact, the 24-bit LSB of UATI identifies the AT within the subnet, while the CC identifies the subnet. In one example, the CC is concatenated with the 24 LSBs of the UATI to form the LCM.

Once in communication, the LCM does not change. Problems arise when ATs cross subnet boundaries. Since each subnet may include multiple cells, very similar subnets may have the same CC. Although the CC to UATI mapping described above is provided for adjacent subnets, ATs may enter subnets that do not have this mapping information. In this case, there will be uncertainty in determining the full UATI. In other cases, the two ATs may be from different subnets with the same CC. If the LSBs of the UATIs of the two ATs are the same, the LCMs of the two ATs may be the same, with the result that the signals from the two ATs interfere with each other (ie, mutual multipath interference occurs).

There is a need to generate unique identifiers for remote stations in wireless communication systems. Furthermore, there is also a need for identifier management when a mobile station crosses sector boundaries while on a traffic channel (ie, connected state). There is therefore a need for a method of accurately identifying subnets when crossing subnet boundaries in a wireless communication system. There is also a need to generate non-overlapping subnet mask and identifier information for multiple subnets.

Description of drawings

Fig. 1 is a wireless communication system;

2 is a wireless communication system including subnets, wherein each subnet includes three cells, and each cell includes six sectors, and the communication system has a color code allocation scheme for the subnets;

Figure 3 is a flowchart illustrating one embodiment of a method for assigning a long mask (LCM) to an access terminal (AT);

Figure 4 is a network device for providing control over generation of LCMs in compliance with mobility standards;

Figure 5 illustrates the movement of an AT with the same LCM but originating from a different subnet moving to a new subnet;

Fig. 6 is the distribution of color code (CC) to the communication system;

Figure 7 is a flowchart illustrating an alternative embodiment of a method for assigning LCMs to ATs;

FIG. 8 is a timing diagram illustrating LCM reallocation;

Figure 9 is a flowchart illustrating one embodiment of a method of allocating LCMs using mobility criteria.

Detailed ways

HDR subscriber stations, referred to herein as access terminals (ATs), may be mobile or stationary, and may communicate with one or more HDR base stations, referred to herein as modem pool transceivers (MPTs). The access terminal sends and receives data through one or more modem pool transceivers connected to the HDR base station controller, referred to herein as a modem pool controller (MPC). Modem pool transceivers and modem pool controllers are part of a network called an access network. The access network transports data packets between multiple access terminals. The access network may be further connected to additional networks external to it, such as a corporate intranet or the Internet, and data packets may be communicated between individual access terminals and such external networks. An access terminal that has established an active traffic channel connection with one or more modem pool transceivers is called an active access terminal and is said to be in traffic. An access terminal that is in the process of establishing an active traffic channel connection with one or more modem pool transceivers is said to be in a connection establishment state. An access terminal may be any data device that communicates through a wireless channel or through a wired channel such as fiber optic or coaxial cable. An access terminal may also be any of a number of types of devices including, but not limited to, PC cards, compact flash memory, external or internal modems, or wireless or wireline telephones. The communication link through which the access terminal sends signals to the modem pool transceiver is called the reverse link. The communication link through which the modem pool transceiver sends signals to the access terminal is called the forward link.

The wireless communication system is shown in Fig. 2, where each hexagon represents a cell. Each cell is composed of six sectors. Three cells form a subnet. When a mobile station or access terminal (AT) initiates communication with an access network (AN), a universal access terminal identifier (UATI) is used to identify the AT and a long mask (LCM) is generated. The LCM is generated based on the color code and the 24 least significant bits (LSBs) of the UATI, which is associated with the UATI at which the mobile station was assigned a traffic channel. In one example, if the AT has been assigned a traffic channel, as in Figure 2 sector c, the LCM may include the appropriate color code and UATI.

Once the communication is in progress, some problems may arise when the AT crosses the subnet boundary. Referring to FIG. 2, the subnet 200 includes three cells. Subnet 200 is assigned a color code (CC) "blue", which corresponds to the subnet ID of subnet 200 . Subnet 200 is adjacent to subnet 300 and subnet 400 . Subnets 300 and 400 have the same CC "ash". However, the CC of subnet 300 corresponds to the subnet ID of subnet 300 , and the CC of subnet 400 corresponds to the subnet ID of subnet 400 . Subnets 300 and 400 have different subnet IDs. The subnet ID of subnet 300 is S1, and the subnet ID of subnet 400 is S2. Note that the subnet ID corresponds to the MSB of the UATI. If an AT enters subnet 200 from sector 'c' of subnet 300, its CC is mapped to subnet IDS1. If an AT enters subnet 200 from sector 'f' of subnet 400, its CC is mapped to subnet ID S2. As a result, if an AT accesses a sector in the middle of subnet 200 with color code 'gray', the mapping from CC to subnet ID may be ambiguous since the correct mapping cannot be determined for that sector.

Another problem related to the above is that the long mask (LCM) of an AT entering subnet 200 from sector 'c' may conflict with the LCM of an AT entering subnet 200 from sector 'f'. A unique identifier needs to be generated for a remote station in a wireless communication system. There is also a need for identifier management when crossing sector boundaries in cellular systems.

The following discussion illustrates an embodiment in which the rules for CC planning are presented. CC is an 8-bit field and thus can have 256 different values. To provide a color-coding scheme, a system is specified such that no subnet is adjacent to a subnet with the same CC value. A subnetwork implementation that satisfies this constraint is shown in Figure 2.

FIG. 3 illustrates a method for assigning LCMs to an AT by checking the AT's active pilot set (Active Set). The Active Pilot Set (AS) defines the set of pilots on which the AT can operate. The set of pilots is given to the AT by the AN through a channel allocation message. The AT establishes communication while in the first subnet Subnet ₁ . As shown, in step 500, the AN assigns an AT identifier, namely UATI ₁ , according to the initial subnet ₁ . In step 502, the AN generates an LCM, LCM ₁ , from UATI ₁ and CC corresponding to subnet ₁ . In step 504, the AN assigns LCM ₁ to the AT. At decision diamond 506, the AN determines whether any member of AT's AS belongs to subnet ₁ . If any member of AS belongs to subnet ₁ , then at step 508 LCM ₁ is reserved for AT. If none of the members of the AT's AS belong to subnet ₁ , processing continues to step 510 to assign a new identifier based on the AT's current location in subnet ₂ . AN generates LCM ₂ according to UATI ₂ and CC of subnet ₂ in step 512 . In step 514, the AN assigns LCM ₂ to the AT.

FIG. 4 illustrates an AN apparatus for implementing the method in FIG. 3 . The device 600 includes a transmitting circuit 610, a receiving circuit 616, a controller 620 and a memory 614, all of which are connected to a bus 618 for communication. Memory 614 may be used to store a list of active pilot sets for at least one AT. The apparatus includes an access terminal identifier generator, a UATI generator 622 , an LCM generator 612 and a mobility evaluation unit 624 . Mobility evaluation unit 624 compares the AT's current location to mobility criteria. In one embodiment, the mobility criteria are as given in decision diamond 506, where mobility evaluation unit 624 determines whether any member of the AS belongs to the initial subset of ATs. Mobility assessment unit 624 retrieves any required information from memory 614 . If the mobility evaluation unit 624 judges that the mobility criterion is not met, the UATI generator 622 assigns a new UATI to the AT according to the AT's current location. LCM generator 612 then generates an LCM based on the new UATI and CC of the current subset of ATs.

This additional restriction imposed only by CC allocation does not solve all of the above problems. Figure 5 illustrates a scheme for introducing uncertainty into CC to UATI mapping. In this case, AT 650 establishes communication in subnet 652 with red CC. AT 660 establishes communication in subnet 656, which also has a red CC. When the subnet IDs of the respective subnets are different, the AT 650 and the AT 660 may be assigned a common LSB portion of the UATI. In this case, when AT 650 and AT 660 enter the same subnet 654 with a blue CC, the new subnet 654 sees one as a multipath to the other.

Thus, to reduce the uncertainty that this situation may introduce and to increase the certainty of UATI and LCM allocation, one embodiment defines a Neighboring Subnet List (NSL) for a sector within subnet X, as A collection of X-adjacent subnets. For example, in Figure 6, the NSLs associated with sectors in subnet "1" are the set {2, 3, 4, 5, 6, 7, 8, 9}. If the terminal constructs an LCM with a CC associated with subnet Y, the LCM is considered to belong to subnet Y. If subnet X constructs an LCM with CCs related to subnet Y, then subnet X is considered to be the "shadow area" of subnet Y.

Let 'd', associated with CC planning in the system, be the minimum number of subnets spanned from a subnet with a given CC to another subnet with the same CC. Figure 6 illustrates a CC planning scheme with 9 CCs. Individual subnets are identified by numbers. As shown, the distance d from one subnet to another with the same CC is 2. Define the minimum distance (MD) for CC planning to be equal to the lower bound of d/2. For example, in FIG. 6, d is equal to 2 and MD is equal to 1. It is expected that CC plans have a minimum distance of at least 1. Subnet 'X' is considered to be 'n' from subnet 'Y' if the minimum number of subnets spanned from a sector in subnet 'Y' to a sector in subnet 'X' is 'n' Jump.

When each sector knows the subnet IDs associated with neighboring subnets, the radio access network can then obtain this information through discovery. Once the neighbor of any member of the active pilot set belongs to a subnet whose neighbor subnet list does not include the subnet ID to which the LCM belongs, the AN or base station controller closes the connection. When reestablishing the connection, the AT constructs the LCM with the new value of the CC.

7 illustrates a method of assigning AT identifiers by evaluating AT mobility and determining when to reallocate new identifiers. _In step 700, the AN assigns the AT identifier LCM ₁ associated with the subnetwork ₁ within which the AT establishes communication. In step 702, the AN establishes communication with the AT. At decision diamond 704 , the AN determines whether the AT is moving to a new subnet, and if so, at step 706 determines the NSL for the new subnet. In step 708, the AN determines whether any neighboring AS includes the shadow area of subnet ₁ , and if so, in step 710, the AN closes the connection to reallocate the LCM for the AT. When reallocating a connection, the AT constructs the LCM with the new value of the CC, ie, the CC of the new subnet.

Figure 8 illustrates the use of the first LCM during the time period ending at _t1 . During this time period, the AT communicates within the subnet with the first CC. At time _t1 , the AT enters a new subnet with a second CC. Note that the AT may not re-establish communication until time _t2 . Achieving this does not require frequent closing of the connection, but allows the endpoint to keep the connection open while residing in a subnet ring around the subnet it received the LCM from.

Figure 9 illustrates a method of assigning AT identifiers according to one embodiment. At step 800, the AN assigns the AT a first identifier corresponding to subnet ₁ . The AN then establishes communication with the AT at step 802 . The AT then enters subnet ₂ , and at step 804, the AN communicates with the AT in subnet ₂ . At decision diamond 806, the AN determines whether subnet ₂ satisfies the mobility criteria of the AT. If the mobility criteria are met, then at step 808 the system maintains the AT identifier. If the mobility criteria are not met, the system assigns the AT a new identifier corresponding to the new subnet _Subnet2 .

If MD is greater than '1', the algorithm can be extended where the base station controller can close the connection as soon as any member of the active pilot set has a neighbor belonging to a subnet more than MD hops away from the subnet to which the LCM belongs . This extension may require sectors within each subnet to know how many hops they are from a particular subnet. This information is available in the base component.

The present disclosure provides various methods for assigning AT identifiers to reduce the uncertainty of CC value to full UATI value mapping to avoid double assignment.

Those of skill in the art will realize that information and signals may be represented by any of a variety of technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols and chips that may be mentioned above may be represented by voltage, current, electromagnetic wave, magnetic field or particle, light domain or particle or any combination of the above.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented in electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, functional blocks, modules, circuits, and steps have been described above generally in terms of their respective functions. Whether the functionality is implemented as hardware or software depends upon the particular application and design constraints placed on the overall system. Skilled persons can realize the described functions of each specific application in different ways, but the determination of this realization method should not be interpreted as a departure from the protection scope of the present invention.

A general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or designed to Combinations of the functions described herein are performed to implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors coupled to a DSP core, or any other such configuration.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be directly included in hardware, a software module executed by a processor, or a combination of both. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integrated into the processor. The processor and storage medium may reside in the ASIC. The ASIC may reside in a user terminal. Alternatively, the processor and storage medium may reside as discrete components in the user terminal.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims (20)

1. access network device, it comprises:

Be used to access terminal to distribute the unit of first identifier, described first identifier is corresponding with first subnet;

Be used for described first subnet in described access terminal set up the unit of communicating by letter;

Be used for the unit of communicating by letter with the described access terminal in second subnet;

Be used to judge whether described second subnet satisfies the unit of the mobility criteria of described access terminal; With

Being used for when described second subnet does not satisfy described mobility criteria is the device that described access terminal is redistributed second identifier, and wherein, described second identifier is corresponding with described second subnet.

2. access network device as claimed in claim 1 is characterized in that, described first identifier is first long code mask.

3. access network device as claimed in claim 2 is characterized in that, described first long code mask comprises the part of the first clean culture access terminal identifier and corresponding to the colour coding of described first subnet.

4. access network device as claimed in claim 1 is characterized in that, the described unit that is used to judge comprises that also arbitrary member of the effective pilot set that is used to judge whether described access terminal belongs to the unit of described first subnet.

5. access network device as claimed in claim 1 is characterized in that, the described unit that is used to judge also comprises:

Be used to generate the unit of the adjacent subnet tabulation of described second subnet; With

Be used to judge whether arbitrary effective pilot set of any neighbor of described adjacent subnet tabulation comprises the unit of the shadow region subnet of described first subnet, and wherein, described first subnet has identical colour coding with described shadow region subnet.

6. device, it comprises:

Access terminal identifier maker, it is applicable to that the function with first subnet generates the access terminal identifier; With

The mobility evaluation unit, it is applicable to whether the current location of judging access terminal satisfies mobility criteria, wherein, does not satisfy mobility criteria in order to respond, described mobility evaluation unit initiates to generate new access terminal identifier.

7. device as claimed in claim 6 also comprises:

Memory Storage Unit, it is applicable to described access terminal stores effective pilot set information,

Wherein, whether described mobility criteria checking has at least one member of effective pilot set of described access terminal to belong to described first subnet.

8. device as claimed in claim 6 also comprises:

Memory Storage Unit, it is applicable to the adjacent subnet tabulation of storage, wherein, whether described mobility criteria inspection has arbitrary effective pilot set of arbitrary neighbor of described adjacent subnet tabulation to have and the identical colour coding of described first subnet.

9. device as claimed in claim 8 is characterized in that, the minimum range that has between the subnet of same color is 1.

10. device as claimed in claim 8 is characterized in that, described access terminal identifier is the long code mask based on clean culture access terminal identifier.

11. device as claimed in claim 10 is characterized in that, described clean culture access terminal identifier is relevant with subnet.

12. device as claimed in claim 10 is characterized in that, described colour coding is the value based on described clean culture access terminal identifier, and it is mapped to subnet identifier.

13. a device, it comprises:

Processing unit, it is applicable to the operation computer-readable instruction; With

Memory Storage Unit, it is applicable to that storage is used for the computer-readable instruction of following operation:

For access terminal is distributed first identifier, described first identifier is corresponding with first subnet;

Set up with the interior described access terminal of described first subnet between communicate by letter;

Communicate with the described access terminal in second subnet;

Judge whether described second subnet satisfies the mobility criteria of described access terminal; With

Be that described access terminal is redistributed second identifier when described second subnet does not satisfy described mobility criteria, wherein, described second identifier is corresponding with described second subnet.

14. method as claimed in claim 13 is characterized in that:

Described mobility criteria judges whether described second subnet and described first subnet are distal at a distance of minimum range,

Described minimum range is to have half of distance between the subnet of same color,

Distance between the described subnet with same color be described in the middle of the number of subnet,

Each colour coding is mapped to subnet identifier.

15. a method, it comprises:

For access terminal is distributed first identifier, described first identifier is corresponding with first subnet;

Set up with described first subnet in described access terminal between communicate by letter;

Communicate with the described access terminal in second subnet;

Estimate the mobility criteria whether described second subnet meets described access terminal; With

Be that described access terminal is redistributed second identifier when described second subnet does not satisfy described mobility criteria, wherein, described second identifier is corresponding with described second subnet.

16. method as claimed in claim 15 is characterized in that, described mobility criteria judges whether described second subnet is distal to minimum range apart with described first subnet.

17. method as claimed in claim 15 is characterized in that, redistributes described second identifier and comprises:

Redistribute message to described access terminal transmission.

18. method as claimed in claim 15, it also comprises:

For described second subnet generates adjacent subnet tabulation.

19. method as claimed in claim 18, it also comprises:

Judge whether arbitrary member of described adjacent subnet tabulation has effective pilot set of the shadow region subnet that comprises described first subnet.

20. method as claimed in claim 19, it also comprises:

If arbitrary member of described adjacent subnet tabulation has effective pilot set of the shadow region subnet that comprises described first subnet, then close and being connected of described access terminal.

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