JP4593528B2 - Packet transmission schedule management system and packet transmission schedule management method - Google Patents

Description

  The present invention relates to a packet transmission schedule management system and a packet transmission schedule management method for managing a transmission schedule of radio packets in a mobile communication system.

  In a mobile communication system, data is transmitted between a base station and a terminal in packet units of a predetermined length. When there are a plurality of wireless lines, the timing (schedule) of transmitting a packet between the base station and the terminal is managed in the line conditions and the like (see, for example, Patent Document 1).

  Typical packet scheduling includes MaxC / I method, Proposional Fairness (PF) method, RoundRobin (RR) method and the like. Above all, the PF method is a scheduling algorithm that can improve the sector throughput and consider the fairness in resource allocation among users in mobile communication systems such as CDMA2000 HDR and W-CDMA HSDPA (3rd generation: 3.5G). It has been adopted.

The packet scheduler employed in such a 3.5G mobile communication system functions as a time scheduler that assigns time slots in consideration of the channel quality of each user.
JP 2003-153339 (FIG. 1, pages 4-6)

  In the conventional packet scheduler as described above, transmission of packets is generally controlled by a single scheduling algorithm. However, since each scheduling algorithm has both advantages and disadvantages, different users have different users. It has been difficult to adaptively allocate resources according to traffic characteristics and user requirements.

  For this reason, 3.9G (3.9th generation) systems and 4G (4th generation) movements that are expected to packetize various services with different required QoS such as low-speed communication such as voice and high-speed data transmission. There was room for improvement in the body communication system.

  The present invention has been made in view of the above-described problems, and provides a packet transmission schedule management system and a packet transmission schedule management method capable of controlling the transmission conditions of wireless packets in accordance with the traffic state. With the goal.

In order to solve the above-described problem, a packet transmission schedule management system according to the present invention operates in parallel with different algorithms, and manages a plurality of sub-control units that manage the transmission schedule of radio packets, and the state of user traffic. A traffic observation unit for detecting user type identification information indicating the type of traffic detected, a packet scheduling control unit for selecting a sub control unit corresponding to the user type identification information, and a sub control unit selected by the packet scheduling control unit There the frequency blocks used for transmission of the radio packet that manages transmission schedule, to the user of the transmission data, characterized by comprising a frequency block group determination means for allocation.

In the present invention, the contract information defined for each user associated with the user type identification information and the requested QoS information that is the quality of service required according to the contract information and the traffic type are referred to. The scheduling control means corresponding to each traffic is selected.
In the above invention, the frequency block group determining means allocates the frequency block groups so as to overlap each other, assigns the same frequency block to a plurality of sub-control units, and determines a predetermined sub-control in the same frequency block. Distribution according to the priority order of each section.
Furthermore, the above invention is characterized in that it further comprises a conversion unit for converting the transmission data to which the frequency block is allocated by the frequency block group determination means, from serial data to parallel data.

The packet transmission schedule management method according to the present invention is a packet transmission schedule management method for managing a radio packet transmission schedule using a plurality of sub-control units that control radio packet scheduling with different algorithms in a base station. The base station traffic observation unit detects the user traffic status and determines the user type identification information indicating the traffic type, and the sub-control unit is operated in parallel to support the user type identification information. It performs scheduling of radio packets by algorithms which, by the packet scheduling control unit of the base station, selecting a sub-control unit corresponding to the user type identification information, in the frequency block group determination means of the base station, packet scheduling system The frequency blocks used for transmission of the wireless packet sub-controller selected by the Department manages the transmission schedule, to the user of the transmission data, characterized by a step of allocating.

  In the present invention, identification information (user type identification information) indicating the type of traffic is detected by detecting a user's traffic state, and scheduling of radio packets is controlled by different algorithms according to the user type identification information. By selecting the one used for managing the transmission schedule of the radio packet corresponding to the user from the scheduling control means, and managing the transmission schedule of the radio packet corresponding to the user using the selected scheduling control means, It is possible to control the transmission condition of the wireless packet according to the traffic state.

  Further, according to the distribution of the user type identification information corresponding to each user to be provided with service, each scheduling control means determines the distribution (frequency block group) of frequency blocks used for transmission of radio packets for managing the transmission schedule. In this way, the bandwidth can be used effectively according to the actual traffic conditions.

  The present invention can be applied to a mobile communication system that provides a communication service to a terminal such as a mobile phone.

(System configuration)
A mobile communication system according to an embodiment of the present invention includes a base station 100 configured as shown in FIG. 1, for example, and a terminal 200 configured as shown in FIG. 2, for example. This mobile communication system is configured to perform multi-carrier modulation / demodulation wireless communication such as MC-CDMA between the base station 100 and the terminal 200.

  The base station 100 shown in FIG. 1 described above includes, for example, a scheduling management unit 120 that manages a schedule of transmission data packets, a transmission unit 110 that modulates transmission data into a radio signal and transmits the data, and traffic in the transmission unit 110 A traffic observation unit 141 for observation, a user traffic information collection unit 142 for collecting information on user traffic, and the like are provided. Of the transmission unit 110, a plurality of modules 111 to 114, 131, and 132, which will be described later, are provided, so that the scheduling management unit 120 performs scheduling management for a plurality of transmission channels and a plurality of radio channels. It has become.

  The transmission unit 110 includes, for example, a data stream output unit 111 to which a data stream such as audio data and communication data is supplied, a channel encoding unit 112 that performs error correction encoding of the data stream, and a complex symbol from the encoded data. A primary modulation unit 113 for generation and a buffer memory 114 for temporarily holding the modulated data are provided.

  Further, the scheduling management unit 120 includes an RR (Round Robin) sub-control unit 121 that performs packet scheduling by the Round Robin method, a PF (Proportional Fairness) sub-control unit 122 that performs packet scheduling by the Proportional Fairness method, Sub-control unit 123 for MaxC / I (Maximum CIR) that performs packet scheduling by the Maximum CIR method, and sub-control unit 121 for RR used for managing the transmission schedule of radio packets for each transmission channel. A packet scheduling control unit 124 that selects the control unit 123.

In accordance with the RR method, the RR sub-control unit 121 sequentially gives a packet transmission right and transmits packets even if there is a traffic difference between users. In accordance with the PF method, the PF sub-control unit 122 calculates an evaluation value from the channel quality on the terminal side and past throughput using an evaluation function f (n) such as the following equation, and based on this evaluation value, Determine the user to whom to assign.

  Further, the MaxC / I sub-control unit 123 allocates all resources to the user with the best channel state according to the MaxC / I method. In this mobile communication system, the RR sub-control unit 121 to the MaxC / I sub-control unit 123 operate in parallel.

  Transmitter 110 corresponds to a radio channel used for radio packet transmission in accordance with control from spreading processing section 131 that spread-codes transmission channel data (transmission data) stored in buffer memory 114 and control from packet scheduling control section 124. Transmission subcarrier determining section 132 that determines transmission subcarriers to be transmitted, S / P conversion section 133 that performs serial / parallel conversion (S / P conversion) of transmission data, and inverse FFT that generates wideband signals by performing inverse FFT conversion (IFFT) section 134 and GI adding section 135 that adds a guard interval (GI) before and after a signal corresponding to transmission data.

The traffic observation unit 141 observes traffic on the transmission channel from the data stream output unit 111 of the transmission unit 110 and notifies the user traffic information collection unit 142 of the result. The user traffic information collection unit 142 obtains contract information 151 corresponding to the contract content defined for each user, and requested QoS information 152 indicating the quality of service required according to the contract content and the type of traffic. For example, referring to table data as shown in Table 1, information indicating the types corresponding to these (user type: identification information indicating the type of user traffic) is analyzed, and the analysis result is transmitted to the packet scheduling control unit 124. Notify

  Which one of the scheduling algorithms by the RR sub-control unit 121 to the MaxC / I sub-control unit 123 is followed by the traffic of each user, for example, as shown in Table 1 above, the characteristics of the user traffic (real-time type) Alternatively, it is determined according to non-real-time type, transmission speed, user billing contract status, etc.

  In Table 1, D, S, and B are parameters indicating the type of traffic, D is a parameter indicating whether it is a real-time type (D0) or non-real-time type (D1), and S is a high-speed transmission type such as a moving image. (S0) is a parameter indicating whether it is a low-speed transmission type (S1) such as voice communication, and B is a parameter indicating whether it is a premium contract type (B0) or a best effort contract type (B1) such as bandwidth guarantee. An algorithm used for packet scheduling (corresponding to the RR sub-control unit 121 to the MaxC / I sub-control unit 123) is defined in association with each user type corresponding to the state of these parameters.

  In this way, by selecting the RR sub-control unit 121 to the MaxC / I sub-control unit 123 used for packet scheduling according to the user type, packet scheduling can be controlled according to user traffic. Thereby, transmission conditions can be controlled according to the traffic state. The MaxC / I method can optimize the throughput, but the fairness among users is low. The RR method and the PF method are slightly inferior in throughput, but the fairness between users is high. Therefore, by appropriately selecting the RR sub-control unit 121 to the MaxC / I sub-control unit 123 used for scheduling according to the user type, it is possible to simultaneously realize improvement in throughput and maintenance of fairness among users.

  On the other hand, the terminal 200 includes a receiving unit 210 that extracts a data stream from the received radio signal.

  The receiving unit 210 includes a GI removing unit 211 that removes a guard interval added to a radio signal, an FFT unit 212 that performs Fourier transform to extract a frequency domain signal, and a control CH receiving unit that receives a control channel signal. 213, a symbol extraction control unit 214 that determines a frequency block to which a symbol is allocated from a signal of a control channel, an allocation subcarrier selection unit 215 that selects a subcarrier corresponding to the frequency block to which the symbol is allocated, P / S conversion unit 216 that generates serial data by performing parallel-serial conversion, despreading processing unit 217 that performs despreading processing, propagation path estimation unit 218 that estimates the state of the propagation path of the radio channel, and estimation results And a propagation path compensator 219 for compensating received symbols.

  Furthermore, the reception unit 210 includes a primary demodulation unit 221 that performs demodulation processing corresponding to the processing by the primary modulation unit 113 described above, and a channel decoding unit 222 that performs error correction of the demodulated data stream.

  On the base station 100 side, the data stream from the data stream output unit 111 is subjected to channel coding and interleaving processing by the channel coding unit 112, and then the primary modulation unit based on the quality information (CSI) notified by the terminal 200 on the user side Adaptive multilevel modulation is performed at 113. The complex symbol after the primary modulation is spread and supplied to the scheduling manager 120 via the buffer memory 114. The scheduling management unit 120 assigns a frequency block for transmitting a complex symbol after selecting a scheduling algorithm to be applied according to the type of user traffic notified from the user traffic information collection unit 142. Here, user index information and modulation multilevel information are also transmitted for each frequency block.

  After user symbols to be transmitted in all frequency blocks are determined by the transmission subcarrier determination unit 132, serial / parallel conversion is performed by the S / P conversion unit 133, inverse Fourier transform is performed by the IFFT unit 134, and a GI addition unit 135 adds a guard interval (GI) to generate a transmission signal (MC-CDMA symbol).

  On the terminal 200 side, the guard interval is removed from the received signal by the GI removal unit 211, the Fourier transform is performed by the FFT unit 212, the parallel / serial conversion is performed by the P / S conversion unit 216, and the despreading processing unit 217 performs the despreading processing. Perform diffusion processing. The demodulated symbol identifies the frequency block in which the user data is stored based on the user index and modulation multilevel number information received via the control CH receiver 213 (by the assignment subcarrier selector 215), The demodulator 221 demodulates the complex symbol into the bit stream. The demodulated bit stream is deinterleaved and channel decoded by the channel decoding unit 222 to obtain received data (voice data, communication data).

  By the way, in this mobile communication system, a radio packet between the base station 100 and the terminal 200 is transmitted as a scheduling algorithm (RR sub-control unit 121 to MaxC / I sub-control unit according to the user traffic state and contract contents). 123), the transmission schedule is managed.

  As shown in FIG. 3, for example, a band used for radio communication between the base station 100 and the terminal 200 is a predetermined bandwidth obtained by blocking a plurality of subcarriers (Δf [direct frequency interval] × NB [subcarrier Number]) for each frequency block. The width of this frequency block (Δf × NB) is set to be equal to or less than the correlation frequency bandwidth.

  In the present embodiment, the transmission subcarrier determining unit 132 includes a function of a frequency block group determining unit that determines allocation to each scheduling algorithm in the frequency domain. FIG. 4 is a flowchart showing a procedure of frequency domain allocation (frequency block group distribution) by transmission subcarrier determining section 132. Here, the ratio of the frequency block groups to which the RR sub-control unit 121 to the MaxC / I sub-control unit 123 respectively assign transmission symbols is, for example, as shown in FIG. The ratio is variable.

  Specifically, as shown in FIG. 4, the transmission subcarrier determination unit 132 determines the number of connected users and the assumed traffic volume observed (S12) by the traffic observation unit 141 for the frequency block group (S11) allocated by the initial setting. The channel quality of each terminal is continuously calculated based on the user type, etc., the evaluation value is calculated using the evaluation function f (i) as shown below, and the frequency block group is allocated based on this evaluation value. The user who assigns the slot is determined (S13).

More specifically, when determining the frequency block, the traffic observation unit 141 observes the number of connected users, the assumed traffic volume, the user type, and the like, and evaluates the distribution using, for example, an evaluation function represented by the following equation.
Here, m _i is the number of users of user type i, t _i is the average transmission rate of user type i, and k is the total number of user types.

  For example, the total number k of user types is 3, and in the initial state, the allocation to each scheduling algorithm is equally divided into three, but based on the above evaluation function, the ratio f of the evaluation functions of user type 1 to user type 3 ( 1): When f (2): f (3) is 1: 2: 2, for example, as shown in FIG. 7, RR sub-control unit 121 to MaxC / I sub-corresponding to each user type A frequency block is allocated to the control unit 123 according to the ratio 1: 2: 2.

  For example, if the total number of subcarriers is 1024 and there are 8 subcarriers per block, the total number of frequency blocks is 128. If these 128 frequency blocks are allocated according to the above ratio, a frequency block group composed of 51 blocks for the MaxC / I sub-control unit 123 and a frequency block group composed of 51 blocks for the PF sub-control unit 122 The frequency block group consisting of 26 blocks is assigned to the RR sub-control unit 121.

  In this embodiment, the ratio of the frequency block group is variable according to the evaluation function as shown in FIG. 6, but the present invention is not limited to this and is fixed in advance. Alternatively, all frequency blocks may be simply divided into three, or proportionally distributed according to the ratio of user traffic handled by each scheduling algorithm. Further, each of the RR sub-control units 121 to MaxC / I sub-control unit 123 may perform allocation to different frequency blocks as shown in FIG. Also, as shown in FIG. 8, it is possible to allocate the same frequency block by allocating the frequency block groups so as to overlap each other. In this case, the priority order of allocation may be determined in advance among MaxC / I, PF, and RR.

(Packet transmission schedule management method)
By operating the packet transmission schedule management system having the above configuration, the packet transmission schedule management method of the present invention can be implemented. FIG. 5 is a flowchart showing the operation of the packet transmission schedule management system according to this embodiment. Here, a case will be described as an example where frequency blocks corresponding to each RR sub-control unit 121 to MaxC / I sub-control unit 123 are allocated according to the distribution of user traffic corresponding to the user type, for example.

  First, the input data (data stream) is monitored by the traffic observation unit 141, the user type of each input data is determined (S101), and the user traffic information collection unit 142 uses table data based on the contract information and the requested QoS information. Then, the scheduling algorithm associated with the user type is referred to (S102). Then, an allocation frequency block group for the scheduling algorithm is selected (S103).

  Next, a scheduling algorithm corresponding to each user type is determined. For example, when the user is type 1, the allocation user is determined in the RR frequency block using the RR algorithm (S105 to S106), and when the user is type 3, the PF algorithm is used. Then, the assigned user is determined in the PF frequency block (S107 to S110), and when the user is type 2, the assigned user is determined in the MaxC / I frequency block using the MaxC / I algorithm ( S111 to S114).

  In the case of types 2 and 3 described above, the traffic observation unit 141 receives a report of reception quality from the user side (S108 or S112), and assigns frequency blocks according to the reception quality (S109 to S110, S113). ~ S114). In particular, in the present embodiment, when the user is type 3, the evaluation function value for each user is further calculated, and the frequency block is assigned in consideration of the calculation result (S109).

  Thus, by controlling the frequency block allocation according to the user-type distribution, the bandwidth can be used effectively according to the actual traffic conditions.

It is a block diagram which shows the structural example of the base station which comprises the radio | wireless communications system which concerns on embodiment. It is a block diagram which shows the structural example of the terminal which comprises the radio | wireless communications system which concerns on embodiment. It is a conceptual diagram which shows the example of a frequency block. It is a flowchart figure which shows the allocation process of the frequency block group in the radio | wireless communications system which concerns on embodiment. It is a flowchart figure which shows the allocation process of the frequency block in the radio | wireless communications system which concerns on embodiment. It is a conceptual diagram which shows the example of allocation of a frequency block. It is a conceptual diagram which shows the other example of allocation of a frequency block. It is a conceptual diagram which shows the other example of allocation of a frequency block.

Explanation of symbols

100 ... Base station
110: Transmitter
111 ... Data stream output section
112 ... Channel coding section
113: Primary modulation unit
114 ... Buffer memory
120 ... Scheduling management department
121 ... RR sub-control unit
122… Sub control unit for PF
123… Sub control part for MaxC / I
124 ... Packet scheduling controller
131… Diffusion processing part
132: Transmission subcarrier decision unit
133… S / P converter
134… IFFT
135… GI addition part
141… Traffic observation section
142: User traffic information collection unit
151… Contract information
152 ... Requested QoS information
200 ... terminal
210 ... Receiver
211… GI removal part
212… FFT section
213 ... Control CH receiver
214 ... Symbol extraction control unit
215 ... Allocated subcarrier selection unit
216 ... P / S converter
217 ... Despreading processing unit
218 ... Propagation path estimation unit
219 ... Propagation path compensation section
221 ... Primary demodulator
222: Channel decoding unit

Claims (8)

A plurality of sub-control units that operate in parallel with different algorithms and manage the transmission schedule of radio packets,
A traffic observation unit that detects user traffic status and determines user type identification information indicating a traffic type;
A packet scheduling control unit for selecting the sub-control unit corresponding to the user type identification information;
The frequency blocks used for transmission of the wireless packet sub-controller which is selected by the packet scheduling control unit manages the transmission schedule, to the user of the transmission data, providing the <br/> frequency blocks determining means for allocating A packet transmission schedule management system. A plurality of sub-control units that operate in parallel with different algorithms and manage the transmission schedule of wireless packets,
A traffic observation unit for detecting user traffic status and determining user type identification information indicating a traffic type;
Corresponding to each traffic by referring to the contract information defined for each user associated with the user type identification information and the requested QoS information which is the quality of service required according to the contract information and the traffic type. A packet scheduling control unit for selecting the sub-control unit ;
The frequency blocks used for transmission of the wireless packet sub-controller which is selected by the packet scheduling control unit manages the transmission schedule, to the user of the transmission data, providing the <br/> frequency blocks determining means for allocating A packet transmission schedule management system.   The packet transmission schedule management system according to claim 1 or 2, further comprising a conversion unit that converts transmission data to which frequency blocks are allocated by the frequency block group determination unit from serial data to parallel data.   The frequency block group determining means allocates the frequency block groups so that they overlap each other, assigns the same frequency block to a plurality of sub-control units, and in the same frequency block, prioritizes a predetermined sub-control unit. The packet transmission schedule management system according to any one of claims 1 to 3, wherein the packet transmission schedule is managed according to a rank order. A packet transmission schedule management method for managing a transmission schedule of radio packets using a plurality of sub-control units that control radio packet scheduling with different algorithms in a base station,
Detecting a user traffic state by the traffic observation unit of the base station and determining user type identification information indicating a traffic type;
The sub-control unit is operated in parallel, and scheduling of the radio packet is performed by an algorithm corresponding to user type identification information, and the sub-control unit corresponding to user type identification information is set by the packet scheduling control unit of the base station. A step to choose;
In the frequency block group determination means of the base station, the frequency blocks used for transmission of the wireless packet sub-controller which is selected by the packet scheduling control unit manages the transmission schedule, to the user of the transmission data, comprising the steps of: allocating A packet transmission schedule management method comprising: A packet transmission schedule management method for managing a transmission schedule of radio packets using a plurality of sub-control units that control radio packet scheduling with different algorithms in a base station,
Detecting a user traffic state by the traffic observation unit of the base station and determining user type identification information indicating a traffic type;
For each user associated with the user type identification information by the base station packet scheduling control unit , the sub control unit is operated in parallel and performs scheduling of the radio packet by an algorithm corresponding to the user type identification information. Selecting the sub-control unit corresponding to each traffic with reference to the defined contract information and the requested QoS information which is the quality of service required according to the contract information and the type of traffic;
In the frequency block group determination means of the base station , a step of allocating , to user transmission data, frequency blocks used for transmission of radio packets managed by the sub-control unit selected by the packet scheduling control unit ; A packet transmission schedule management method comprising:   7. The packet transmission schedule management method according to claim 5, further comprising a step of converting transmission data to which frequency blocks are allocated by the frequency block group determination means from serial data to parallel data. The frequency block group determination means distributes the frequency block groups so that they overlap, and assigns the same frequency block to a plurality of sub-control units, and in the same frequency block assigned to the plurality of sub-control units. 8. The packet transmission schedule management method according to claim 5, wherein the packet transmission schedule is distributed according to a predetermined priority order of the sub-control units .