JP4732994B2 - Communication processing method in radio base station of mobile communication system - Google Patents

Description

  The present invention relates to a communication processing method in a radio base station of a mobile communication system, and in particular, has a scheduler that handles resource selection such as user selection, power and data length, and a line termination function that terminates a received signal from a core network. The present invention relates to a communication processing method in a radio base station for reducing the processing load in consideration of the processing amount characteristics of each function for a generation mobile communication system.

  In recent years, several high-speed wireless communication systems have been proposed for third-generation mobile communication technology. Among them, IMT-2000 is standardized by ITU (International Telecommunication Union), and 3GPP (3rd Generation Partnership Project) is one of the groups of specific detailed specifications of the standard for realizing the requirements.

  The detailed specifications created in 3GPP are adopted as standards in each region, and there is a method called W-CDMA (Wide Code Division Multiple Access), and the W-CDMA (UMTS) mobile communication system The configuration will be described below.

  FIG. 12 shows the configuration of a W-CDMA mobile communication system. In the figure, 50 is a mobile station such as a mobile phone and a mobile terminal, 51 is a core network including a transmission network such as ATM, and other wired and wireless public networks (PSTN: Public Switched Telecommunication Network), 52 and 53 are Radio network controller (RNC), 54 and 55 are demultiplexers, 56 is a radio base station (referred to as Node B in 3GPP), and a plurality of radio base stations 56-1 to 56-5 are arranged. As a representative, 57 indicates a mobile station (UE: User equipment).

  The core network 51 is a network for performing routing in the mobile communication system, and is connected to, for example, a public telephone network (PSTN), an IP network, a mobile communication network, an ATM switching network, a packet switching network, etc. 50 mobile phones can communicate with a fixed phone or the like via the core network 51.

  Radio base station control devices (hereinafter simply referred to as RNCs) 52 and 53 are positioned as higher-level devices of the radio base station 56, and have a function of controlling these radio base stations (management of radio resources used, etc.). Yes. In this example, the demultiplexer 54 controls the radio base stations 56-1 to 56-3, and the demultiplexer 55 controls the radio base stations 56-4 to 56-5. It also has a handover control function that receives signals from one mobile station 50 from a plurality of subordinate radio base stations, selects data with better quality, and sends it to the core network 51 side during handover. .

  The demultiplexers 54 and 55 are arranged between the RNCs 52 and 53 and the radio base station 56. However, the demultiplexers 54 and 55 can be provided in the RNCs 52 and 53 and demultiplex signals received from the RNCs 52 and 53 to the radio base stations. Then, it outputs to each radio base station, and controls to multiplex the signals from each radio base station and deliver them to each RNC 52, 53 side. Radio base stations 56-1 to 56-3 perform radio communication with the mobile station 50 while radio resources are managed by the RNC 52, and radio base stations 56-4 to 56-5 manage radio resources by the RNC 53. The mobile station 50 is located in the radio area of the radio base station 56, thereby establishing a radio line with the radio base station 56 and communicating with other communication devices via the core network 51. Do.

  The interface between the core network 51 and the RNCs 52 and 53 is an Iu interface, the interface between the RNCs 52 and 53 is an Iur interface, and the interface between the RNCs 52 and 53 and each radio base station 56 is an Iub interface. An interface between the mobile station 50 and the mobile station 50 is referred to as a Uu interface, and a network formed by the devices 52 to 56 is particularly referred to as a radio access network (RAN). The line between the core network 51 and the RNCs 52 and 53 is shared for Iu and Iur interfaces (a plurality of Iur interfaces with a plurality of RNCs), and the RNCs 52 and 53 and the demultiplexers 54 and 55 Are shared for Iub interfaces for a plurality of radio base stations.

  The above is a description of a general mobile communication system, but an HSDPA method having a scheduler and a line termination function has been proposed as a technique that enables high-speed downlink data transmission.

  Hereinafter, HSDPA (High Speed Downlink Packet Access) will be briefly described. HSDPA employs adaptive coding and modulation (AMC), for example, a QPSK modulation scheme (QPSK modulation scheme) and a 16-value QAM scheme (16 QAM scheme) are transferred to the radio base station 56. It switches adaptively according to the radio environment between the stations 50. HSDPA adopts an H-ARQ (Hybrid Automatic Repeat reQuest) system. In H-ARQ, when an error is detected in received data from a radio base station, a mobile station makes a retransmission request (transmission of a NACK signal) to the radio base station. The radio base station that has received this retransmission request retransmits the data, so that the mobile station performs error correction decoding using both the already received data and the retransmitted received data. As described above, in H-ARQ, even if there is an error, by effectively using already received data, the gain of error correction decoding is increased, and as a result, the number of retransmissions is reduced. When an ACK signal is received from a mobile station, data transmission is successful and retransmission is unnecessary, and the next data is transmitted.

  FIG. 13 is an explanatory diagram of radio channels (physical channels) used for HSDPA, and mainly shows main channels in the downlink direction. In the figure, a. CPICH (Common Pilot Channel) is a downlink common channel, and there are two types of primary CPICH and secondary CPICH. One primary CPICH exists in each cell. Used for cell search, etc., and the secondary CPICH is mainly used when an adaptive array antenna is applied. b. Is an SCH (Synchronization Channel), which is a downlink common channel, and has two types, a primary SCH and a secondary SCH, and is used for cell search of a mobile terminal.

  c. Is HS-SCCH (High Speed-Shared Control Channel), d. Is HS-PDSCH (High Speed-Physical Downlink Shared Channel), e. Is HS-DPCCH (High Speed-Dedicated Physical Control Channel). c. HS-SCCH, and d. Both HS-PDSCHs are shared channels in the downlink direction (that is, the downlink that is the direction from the radio base station to the mobile station), and the HS-SCCH is data transmitted on the HS-PDSCH. It is a control channel which transmits various parameters regarding. That is, it is a channel for notifying (notifying in advance) that data transmission is performed via the HS-PDSCH. The various parameters include, for example, modulation scheme information indicating which modulation scheme is used to transmit data by HS-PDSCH, the number of assigned spreading codes (number of codes), and the rate for transmission data Information such as a pattern of matching is included.

  On the other hand, e. The HS-DPCCH is a dedicated control channel in the uplink direction (that is, the uplink from the mobile station to the radio base station), and an error of data received via the HS-PDSCH This is used when the mobile station transmits a reception result (ACK signal, NACK signal) to the radio base station according to presence or absence. That is, it is a channel used to transmit the reception result of data received via the HS-PDSCH. When the mobile station fails to receive data (when the received data is a CRC error, etc.), the NACK signal is transmitted from the mobile station, so the radio base station executes retransmission control. Also, e. As shown in FIG. 4, the HS-DPCCH is a method for measuring the reception quality (for example, SIR: Signal to Intererence power Ratio) of a received signal from a radio base station, and using the result as CQI information (Channel Quality Indicator). Also used to transmit to the station. Based on the received CQI information, the radio base station determines whether the downlink radio environment is good or not. If the radio base station is good, the radio base station switches to a modulation method capable of transmitting data at a higher speed. Switch to a modulation scheme that transmits data and perform adaptive modulation.

  Next, the scheduler will be described. The scheduler determines a transmission target (mobile station) and a transmission speed, a modulation method, and the like based on an index value calculated based on the line quality and the transmission data rate. The scheduler is used in various communication systems. Here, a scheduler applied to a mobile communication system adopting the HSPDA method will be described as an example. In HSPDA, since the physical downlink data channel HS-PDSCH described above is shared by a plurality of mobile stations, it is necessary to select a mobile station to be transmitted, and the scheduler is involved in mobile station selection control.

  FIG. 14 shows a schematic configuration example of the HSDPA system. In this example, a plurality of mobile stations 50-1 to 50-m are connected to the radio base station 56-1, and another plurality of mobile stations 50- (m + 1) to 50-n are connected to the radio base station 56-2. These radio base stations 56-1 and 56-2 are connected to a radio base station controller (RNC) 52. The demultiplexer 54 or 55 shown in FIG. 12 is not shown.

  Two radio base stations 56-1 and 56-2 are connected to the radio base station controller (RNC) 52, and the radio base station 56-1 communicates with the subordinate mobile stations 50-1 to 50-m. The radio base station 56-2 communicates with subordinate mobile stations 50- (m + 1) to 50-n. The scheduler unit 561 of each of the base stations 56-1 and 56-2 selects a mobile station that transmits data based on channel quality information (CQI, H-ARQ information (ACK / NACK information)) received from the mobile station. At the same time (mobile station selection control), the transmission data amount, modulation method, power, etc. are determined based on the CQI information received from the mobile station, and the channel coding unit 560 is instructed. Further, the scheduler unit 561 requests data addressed to each mobile station from the radio base station controller 52 based on the scheduling result (flow control). The radio base station control device 52 holds the data addressed to each of the mobile stations 50-1 to 50-n received via the core network in the RNC buffer unit 520, and the requested mobile unit is requested by the scheduler unit 561. Send data addressed to the station. The buffer units 562 of the radio base stations 56-1 and 56-2 store the data addressed to each mobile station transmitted from the RNC buffer 520 of the radio base station controller 52, and the mobile station designated by the instruction from the scheduler unit 561 The addressed data is input to the channel coding unit 560 in the requested block size. The channel coding unit 560 adds a CRC code for each block to the input data addressed to the mobile station, encodes the data for each predetermined number of blocks, modulates the data according to the modulation method instructed by the scheduler unit 561, and each mobile station. Send to.

  As a user selection algorithm in the scheduler unit 561, a maximum CIR method (Maximum CIR: Carrier-to-Interference power Ratio (corresponding to the above SIR) method), a Proportional Fairness method, a round robin (Round Robin) method, and the like have been proposed. Patent Document 1). The Maximum CIR method is a method of selecting a user with good line quality, but it is not assigned to a user with poor line quality and there is no fairness. In contrast, the Proportional Fairness method uses the following equation (1):

Thus, the index value C _{n (PF)} is calculated, and the one having a high index value C _{n (PF)} is selected, and the throughput is improved while maintaining fairness. In Equation (1), R _n is the instantaneous channel quality, Ave R _n is the average channel quality, and 1-α and 1-β are the respective weighting coefficients. R _n and Ave R _n may be replaced with the amount of data that can be transmitted according to the channel quality instead of the channel quality. Since the scheduler needs to calculate the index value for all users in the corresponding sector every TTI (Transmission Time Interval), the processing amount is proportional to the number of accommodated users regardless of the data rate. In this method, slots are allocated to users who have good instantaneous reception SIR due to fading fluctuation, the number of transmissions between users is almost uniform, and there are fewer users who are not given a transmission opportunity like the maximum CIR method. Also, since slots are allocated when the user's radio link state is good, the effect of improving throughput by AMC is greater than round robin.

  In addition, since the round robin method assigns slots equally regardless of the radio link state between the radio base station and the user, the probability of assigning slots to users with poor radio link status due to fading fluctuation is higher than other methods. There is a problem that the effect of improving the throughput by AMC is small, the retransmission of packets due to packet errors increases, and the overall transmission efficiency is poor.

  The line termination function in HSDPA will be described. The line termination function is a function for processing data so that data transmitted from the core network side by IP or the like is terminated and subsequent processing such as channel coding can be performed. Here, layer 2 studied by LTE (Long Term Evolution, 3GPP) will be described as an example, but the system configuration is almost the same as the configuration example at the time of HSDPA shown in FIG. The explanation will focus on two functions (protocols).

  FIG. 15 shows an LTE layer 2 protocol stack, where 50 is a mobile station, 56 is a radio base station, 521 is an access gateway (aGW), and the access gateway 521 is a call processing monitoring control function, user This is a device that bears functions that are part of the functions of the radio base station controller (RNCs 52 and 53 in FIG. 12) in W-CDMA, such as a plane function (PDCP termination: Packet Data Convergence Protocol) and an IP termination function. The layer 2 functional unit in the radio base station (Node B) is the object of this explanation. From FIG. 15, the layer 2 function is divided into RLC (Radio Link Control) and MAC (Media Access Control) layers. The connection between each layer and the flow of data will be described with reference to FIG.

  FIG. 16 is an explanatory diagram of a data format.

  In the downlink (aGW → Node B) processing in the radio base station (56 in FIG. 15), the a. When the RLC SDU (PDCP-PDU) shown in FIG. 16 is received, the RLC SDU is divided and combined according to the PDU length specified by the scheduler, and then b. And an RLC header (RLC H) as shown in FIG. To the MAC layer shown in FIG. The above process is performed for the number of logical channels multiplexed in the user. In the MAC layer, a header is added to a concatenation of RLC PDUs corresponding to the number of logical channels, and a MAC PDU is assembled. In the example of FIG. 16, the logical channel (LCH) is composed of four channels (# 0 to # 3).

  The uplink (Node B → aGW) processing is basically the reverse of the downlink processing. Specifically, the header information of the MAC PDU is referenced, separated into RLC PDUs, and passed to the RLC layer. In the RLC layer, RLC PDU header information is referenced, RLC SDU is assembled, and transmitted to the access gateway (see Non-Patent Document 2).

  Next, the channel coding function in HSDPA will be described.

  The channel coding function is a function of performing coding processing and physical channel (Physical channel) division processing for transmission to the air on a MAC PDU assembled by the line termination function.

  The procedure of the channel encoding process is shown in FIG. First, a CRC Attach (assignment of cyclic redundancy code) is performed on the MAC PDU (a1 in FIG. 17), a bit scrambling process is performed (a2), and the processed data is converted into a code block (a). Segmentation is performed in units of Code Block (same as a3), and channel coding processing (turbo, convolutional coding) is performed on the divided data units (same as a4). The bit scrambling process is a process of scrambling data by taking an exclusive OR with a certain fixed pattern for a signal after CRC Attach.

  In the next hybrid ARQ process (b in FIG. 17), bit separation (separation) is performed on the data after coding (b1), and two-stage rate matching (Rate Matching) is performed. . First, first rate matching processing is performed (b2 in FIG. 17), and the data after channel coding processing is matched with the virtual IR buffer size (UE buffer size). In the second rate matching (Rate Matching) processing, the data matched to the virtual IR buffer size is used for the air based on parameters determined by the ACK / NACK signal and the control signal for determining the rate matching pattern. In order to match the data length determined by the frame format, a process of repeating or removing bits is performed (b3 in FIG. 17). When there is a retransmission request, the first rate matching process is not performed, the rate matching pattern is changed for the data matched to the virtual IR buffer size at the first transmission, and the rate matching process is performed. After the second rate matching processing, bit correction processing is performed on the data (b4 in FIG. 17), and the hybrid ARQ processing is completed.

  Finally, the data after the bit correction processing is divided into physical channel units (c1 in FIG. 17), and the interleave processing (inter c2) and coordinate relocation (Constellation Re-arrangement: The data is arranged at a coordinate point determined by the phase and amplitude (c3), and mapped to the air transmission format (c4). Interleaving is a process that rearranges the order of bits in order to increase error tolerance in the air. Set rearrangement is a process that rearranges data after interleaving in units of symbols and takes complex conjugates. Thus, the signal point mapping position is changed (see Non-Patent Document 3).

  A channel decoding function in HSDPA will be described.

  The channel decoding function is a function that is positioned upstream of the line termination function in upstream processing, and restores data transmitted by the user (transmission side) through encoding processing. Basically, the reverse of the channel coding process will be performed, so a detailed description will be omitted. However, specific processes include “interleaving” to improve burst error resistance, data length “Rate matching” that performs conversion, “turbo decoding” that is an error correction coding method, “HARQ (hybrid ARQ processing)” that improves signal reliability by retransmission, and the like (see Non-Patent Document 4).

  FIG. 18 shows a configuration of a conventional example, and shows a configuration of uplink and downlink for executing functions of channel termination, channel coding / decoding, and scheduler in a conventional radio base station. Note that the line termination, channel coding, and decoding functions are linked as data exchanges, and the amount of information exchanged between the scheduler and these line termination, channel coding, and decoding processes is small. As described above, it is generally considered that the scheduler and other processing are executed in separate units.

  14 and the related FIG. 15 to FIG. 17 and the like, the channel code (channel coding) / decoding unit and the scheduler unit of the radio base station described in FIG. ). In the figure, 56a is a downlink scheduler DSP, 56b is a downlink RLC / MAC termination encoding preprocessing DSP, 56c is a QB (queue buffer) RLC window buffer, 56d is a downlink encoding DSP, 56e is an uplink scheduler DSP, and 56f is an uplink decoding. The generalized RLC / MAC termination DSP 56g is a CC (Channel Coding) / IR MAC / RLC buffer. In this configuration, separate DSPs called the downlink scheduler DSP 56a and the downlink RLC / MAC termination precoding DSP 56b are used for the downlink processing, and the uplink scheduler DSP 56e and the uplink decoding RLC / MAC termination DSP 56f are individually used for the uplink processing. DSP is used.

There is also a proposal for a mobile communication system, a radio base station, a scheduling device, and a scheduling method that can achieve high throughput while achieving quality assurance for each mobile station and imparting transmission opportunities fairly (Patent Document 1). reference). In this proposed technique, the radio base station assigns a transmission opportunity to the mobile station using the transmission status of packets to the mobile station, radio channel quality information from the mobile station, and the like.
IEICE Technical, RCS2001-291, pp.51-58 “Characteristic Comparison of Scheduling Methods Focusing on Throughput of Each User in Downlink High-Speed Packets” Mar.2002 The Institute of Electronics, Information and Communication Engineers 3GPP LTE document (3GPP TR 25.813 V7.0.0) 3GPP TS 25.212 V7.1.0 (2006-6) 3GPP TS 25.212 V7.1.0 (2006-6) JP 2005-101783 A

  The next-generation high-speed mobile communication system such as HSPDA described above is required to have higher speed and larger capacity than the current W-CDMA mobile communication system. For example, the LTE (Long Term Evolution, 3GPP) standard requires a transmission rate that is approximately 750 times higher than that of the current W-CDMA mobile communication system. Considering this situation, the number of accommodated users is expected to increase further in the future. Further, although the usage status and traffic volume of the high-speed service vary depending on the place and time, as shown in the configuration of the conventional example shown in FIG. 18, the scheduler and the RLC MAC termination encoding process are separate processing devices (DSP). Therefore, it is necessary to provide a large number of processing apparatuses (DSPs), which is inefficient, and there is a problem that the apparatus is increased in size and cost.

  On the other hand, the technique of Patent Document 1 relates to a technique for selecting a mobile station to which a transmission opportunity is assigned from a plurality of mobile stations in a radio base station, and includes each of line termination, encoding / decoding, scheduler, and the like. It is not intended to reduce the number of parts of a device that performs a function and to reduce the size of the device.

  As described above, when a communication control device such as a base station of a high-speed mobile communication system is realized by the conventional method, there are problems that the number of parts is increased and the size of the device is increased.

  The present invention considers the characteristics of the amount of processing for the scheduler, line termination function, and channel encoding / decoding function that constitute the next-generation high-speed mobile communication system, and reduces the processing load as well as various bit rates and the number of sectors. It is an object of the present invention to provide a communication processing method in a radio base station of a flexible mobile communication system corresponding to the above.

  The next-generation high-speed mobile communication system has a scheduler for determining resources such as power and data length, a line termination function for terminating received signals from the core network, and a channel encoding / decoding function. The characteristics of the throughput are different as follows.

Scheduler: processing amount is proportional to the number of users Line termination function unit: processing amount is proportional to data rate Channel encoding / decoding function unit: processing amount is proportional to data rate The image of these processing amount characteristics is shown in FIG. It is shown in (a) and (b) of the principle explanatory diagram of the invention. That is, since the processing amount of the signal processing device of the scheduler is proportional to the number of users, as shown in (a), the processing load is higher in 2 sectors than in 1 sector, and the line termination, channel coding / decoding is performed. Since the functional unit is proportional to the data rate, as shown in (b), the processing load is higher at 100 Mbps × 1 sector than at 25 Mbps × 2 sectors, and each functional unit is separated as shown in FIG. When implemented with devices (devices such as DSP or other processing units), each device needs to have a processing capacity at the maximum processing load. Therefore, the schedulers shown in a1 and a2 in FIG. As shown in the processing load image, the line termination shown in b1 and b2 of (b), and the processing load image of the encoder / decoder, there is a surplus in processing capacity. It made. Note that a1 and b1 indicate the processing load and processing surplus in the case of 100 Mbps per sector (representing the processing capacity together), and a2 and b2 indicate the processing load and surplus in the case of processing 25 Mbps per sector for two sectors. (The processing capacity is expressed together).

  (C) is a processing load image according to the present invention. Based on the processing load conditions of FIGS. 1 (a) and 1 (b), as shown in FIG. 1 (c), the processing unit of the scheduler and the processing unit of the line termination and encoding / decoding unit are the same processing unit. C1 is the processing of the scheduler unit of one sector in the case of 100 Mbps per sector and the processing of the line termination and encoding / decoding unit depending on the total processing capacity of the PU (or DSP). An image of the processing amount characteristic to be executed. C2 is a processing amount characteristic for executing the processing of the two-sector scheduler unit in the case of 250 Mbps per sector and the processing of the line termination and encoding / decoding unit by the entire processing capacity of the DSP. Represents an image.

  In addition, since the processing load is the same for both 100 Mbps × 1 sector and 25 Mbps × 2 sectors, the processing load is made uniform at various data rates and sector configurations, and the processing capability of the device can be fully utilized. Therefore, it is possible to achieve the objectives of reducing the number of parts and high flexibility of operation.

  Further, by adopting a method of performing scheduling processing with the remaining processing load after first assigning processing proportional to the data rate, the number of accommodated sectors per processing unit can be reduced and the number of accommodated users can be increased. it can. For example, in FIG. 1B, by setting 25 Mbps × 2 sectors to 1 sector, the processing load of the line termination and channel coding / decoding functions is halved, and there is a surplus that can be allocated to the scheduling process accordingly. And the number of accommodated users can be increased.

  FIG. 2 shows a configuration example of the present invention. In the figure, 10 is a downlink processing unit that performs processing for transmitting a signal to a terminal such as a mobile station, 10a is an RLC / MAC pre-processing unit (denoted by PU), 10b is a buffer, and 10c is a downlink code. Processing unit (represented by PU), 11 is an upstream processing unit for processing a signal transmitted from a terminal such as a mobile station to a radio base station, 11a is an upstream decoding RLC / MAC processing unit (represented by PU), 11b Is a buffer. “RLC / MAC” of 10a and 11a has the same meaning as described in the configuration of the conventional example of FIG. Note that each PU (processing unit) such as 10a, 10c, and 11a has a known configuration including an information processing device (computer) including a CPU, RAM, ROM, and the like, and executes processing by an installed program. Output. Each processing unit (PU) such as 10a, 10c, 11a can be configured as a device called a known digital signal processor (DSP).

  In the downlink processing unit 10, the RLC / MAC termination, the downlink scheduler, and the pre-encoding process are executed in the same processing unit 10a, and the downlink encoding process is executed by another downlink encoding processing unit 10c. Note that the pre-encoding process represents processes that need to be performed before encoding, such as CRC addition, code segment division, and turbo IL table generation.

  In the configuration of the uplink processing, RLC / MAC termination, uplink scheduler, and decoding processing are executed by the same uplink decoding RLC / MAC processing unit 11a.

    In the following description, since there is basically no difference between the uplink process and the downlink process, the description will focus on the downlink process.

  In the downlink processing unit, RLC termination, scheduling, resource calculation processing, MAC PDU (Media Access Control Protocol Data Unit) assembly is performed in the downlink RLC / MAC encoding preprocessing unit 10a for IP packets input from the core network side. , Pre-coding processing such as turbo IL table generation is performed. The downstream RLC / MAC encoding preprocessing unit 10a and the downstream encoding processing unit 10c are high-performance multiprocessing units, and can be composed of, for example, four processing units.

  (1) Processing of RLC SDU: RLC SDU is generated by this processing.

  (2) RLC ARQ process: This process controls retransmission of the RLC layer.

  (3) Scheduling process: By this process, an index for user selection is calculated for each user, and user selection is performed.

  (4) Resource allocation processing: Resource allocation processing is performed for each sector.

  (5) MAC PDU assembly process: This process assembles the MAC PDU.

  (6) Pre-encoding process: This process adds CRC to the code and performs turbo segmentation.

  By allocating the processing of (1) to (6) to multiple processing units, the processing load is optimally distributed to each PU, thereby realizing uniform processing load and reduction of processing delay. That is, instead of assigning a fixed PU to a certain PU, users are assigned so that the processing load of all PUs is uniform according to the processing load of each PU.

  In the above description, the process for the mobile station in the radio base station has been described. However, in the process for the fixed station rather than the mobile station, scheduler, line termination, encoding / decoding, resource allocation, etc. The principle of the present invention can also be applied to an apparatus that executes processing.

  According to the present invention, the scheduler, the line termination, and the channel encoding / decoding function unit are processed in the same device in a time-sharing manner, so that the processing load is uniformed at various data rates and sector configurations, and the processing capability of the device is fully utilized This makes it possible to achieve the objectives of reducing the number of parts and high operational flexibility.

  And since the surplus of processing capacity can be eliminated by the present invention, the number of accommodated users can be increased from 1.6 times to 1.9 times under the same conditions.

  When the present invention is used, it is possible to increase the number of users that can be accommodated as compared with the case where the present invention is not used. The calculation conditions for the number of users that can be accommodated in this case are shown in FIG. Shown in

  In addition, since it is assumed that the number of accommodated users is small during the initial operation of the mobile communication system, the number of accommodated sectors per processing unit is increased, and operation is performed with a minimum number of cards (packages including processing units). As the number of accommodated users increases, the number of accommodated sectors per processing unit is decreased, and the number of accommodated users is increased.

  In order to execute high-speed mobile communication between a large number of mobile stations and base stations according to the present invention, as shown in FIG. 2 above, the functions of the scheduler, line termination and pre-encoding processing are executed using a multiprocessing unit. FIG. 3 shows the functional blocks in the RLC / MAC encoding preprocessing unit (10a in FIG. 2). This RLC / MAC encoding preprocessing processing unit is composed of four processing units (PU1 to PU4 not shown). Programs corresponding to a plurality of functions are registered in advance in each PU, and call processing is performed. When the functions of the processing units 21, 22, 24 to 26 including the scheduler 23 are activated according to the state and conditions by the control program that executes the functions of the overall control unit 20, and the operations of the specified processing units are completed. The call processing / overall control unit 20 is notified, and each function is executed in a time division manner. The processing unit used is a high-performance multi-core processor (4000 MIPS × 4), and the four processing units (or cores) are hereinafter referred to as PU1, PU2, PU3, and PU4.

  In FIG. 3, 20 is an overall / overall control unit, 21 is an RLC SDU processing unit, 22 is an RLC ARQ processing unit, 23 is a scheduler, 24 is a resource allocation processing unit, 25 is a MAC PDU assembly processing unit, and 26 is before encoding. The processing unit 27 is a buffer.

  The flow of downlink processing (from RLC to pre-encoding processing) in FIG. 3 is shown as the processing flow of the embodiment in FIG. 4 and will be described below in the order of steps S1 to S7 in FIG.

  Step S1: When a call is generated, the call processing / overall control unit 20 sets control parameters necessary for signal processing for each processing unit which is each functional block. In addition, it is determined which PU schedules the user. This process is assigned to PU1.

  Step S2: The RLC SDU processing unit 21 performs IP termination on the IP packet input from the core network (51 in FIG. 12), generates an RLC SDU according to the RLC SDU length, and generates a buffer (27 in FIG. 3). ). This process is also assigned to PU1.

  Step S3: The RLC ARQ processing unit 22 performs a retransmission control process according to the RLC ACK information transmitted with the uplink control signal. Specifically, the corresponding SDU is released at the time of ACK, and nothing is done at the time of NACK (used in the subsequent MAC PDU generation unit). This process is assigned to PU2.

  Step S4: The scheduler 23 calculates an index value for user selection and notifies the resource allocation processing unit. In addition, parameters for calculating index values are received from the resource allocation processing unit 24. This process is shared (shared) by each of PU1 to PU4.

  Step S5: The resource allocation processing unit 24 performs resource calculation such as user selection and transmission data length based on the index value passed from the scheduler 23, and notifies the MAC PDU assembly processing unit 25 of it. This process is assigned to PU3.

  Step S6: Based on the data length notified from the resource allocation processing unit 24, the MAC PDU assembly processing unit 25 combines the RLC SDUs remaining in the buffer, adds an RLC / MAC header, generates a MAC PDU, Transfer to the pre-processing unit 26. This process is assigned to PU4.

  Step S7: The pre-encoding processing unit 26 adds a CRC that is a cyclic redundancy check code, performs processing such as turbo segmentation, and transfers it to the encoding processing unit. This process is assigned to PU4.

  The scheduler in step S4 is shared by each of the PUs 1 to 4, but the processing load is optimally distributed to each PU, thereby realizing uniform processing load and shortening of processing delay. That is, instead of assigning a fixed PU to a certain PU, users are assigned so that the processing load of all PUs is uniform according to the processing load of each PU.

  In addition, user allocation in the scheduler is shared among a plurality of PUs. Details of the user allocation method will be described below.

  FIG. 5 shows an example of a timing chart of user allocation prohibited area calculation by multi-PU (processing unit), and FIG. 6 is a flowchart of user allocation prohibited area calculation shown in FIG. FIG. 7 shows an example of a timing chart of user allocation by multi-PU considering the allocation prohibition area.

  The optimum user allocation method will be described with reference to FIGS.

Step 1 (S1 in FIG. 6): User allocation prohibited area calculation by RLC SDU and RLC ARQ processing e. In FIG. RLC SDU, f. An area to which a user is not allocated is calculated so that the RLC ARQ process and the scheduling process are not overlapped.

Step 2 (S2 in FIG. 6): Scheduling completion time calculation a. ~ D. Assuming that scheduling is performed for the maximum number of users as shown in FIG. 4, the time required for completing scheduling in all PUs 1 to 4 is calculated based on the user allocation method shown in step 5 described later.

Step 3 (S3 in FIG. 6): Determination of resource allocation processing start time g. In the resource allocation / MAC PDU assembly process shown in FIG. 4, since the start condition is that the RLC ARQ process and the scheduling process are completed, the start time is the time when both are completed.

Step 4 (S4 in FIG. 6): Forbidden area calculation from resource allocation process to pre-encoding process g. And h. An area to which a user is not allocated is calculated so that the resource allocation process, MAC PDU assembly process, pre-encoding process and scheduling process shown in FIG.

  Step 5 (S5 in FIG. 6): Users are sequentially assigned to PUs that have the earliest completion of processing outside the prohibited area. A specific example of this user assignment is shown in FIG. In this example, the radio base station is provided with two sectors, sector 1 and sector 2, and the generated call (user) is indicated by “13” and f shown in FIG. Thus, sector 2 is “10”.

  As shown in FIGS. 7A to 7D, forbidden area calculation is performed in steps 1 to 4 by processing other than the scheduler.

  In step 5, user assignment to the PU with the earliest completion of processing is sequentially performed outside the prohibited area. Since the scheduling process start condition is after the RLC SDU conversion process, a user is assigned to each sector immediately after the prohibited area by the RLC SDU conversion process, and PU1 to PU4 are assigned to PU1 to PU4 as shown in g to j of FIG. On the other hand, the allocation of the users 1 to 13 in the sector 1 is executed in the first half cycle, and the user allocation for the users 1 to 10 in the sector 2 is performed in the subsequent cycle.

  FIG. 8 shows a flowchart based on the user allocation method shown in FIGS. Details of processing in the processing unit (downlink RLC / MAC pre-coding processing unit 10a in FIG. 2) will be described with reference to FIG. It should be noted that the user allocation prohibited area calculation is premised on having been calculated before the call is generated.

  Check whether a call has been made (S1 in FIG. 8). If a call has been made, the upper parameters for the user are analyzed, processed as necessary, and set in each function unit (S2). The assigned PU for is determined (S3), and if no call has been made, steps S2 and S3 are skipped. The method for determining the user allocation PU in step S2 is shown in the user allocation method in FIG.

  Next, processing for each user (RLC, scheduling, etc.) is executed for the number of users (S4 to S6 in FIG. 8). Details of the processing for each user are shown in steps S50 to S57. First, it is checked whether the call is released by the user (S50 in FIG. 8). If released, various users initialize parameters and control information. (S51) The process for each user is terminated, and the process for each user for the corresponding user is terminated. If not released, IP termination and RLC SDU are generated (S52). Next, RLS ARQ processing is performed (S54 in FIG. 8), the presence / absence of data in the buffer is checked (S55 in FIG. 8), scheduling is performed if there is data (S56), and scheduling processing is performed if there is no data. To skip. This process is performed for the number of logical channels multiplexed for the corresponding user (S57 in FIG. 8), and the process for each user in the corresponding user is terminated.

  In this embodiment, the above process is performed once per TTI (one cycle) for IP packets and RLC ACKs accumulated during that period.

  Among users and logical channels that have been scheduled, a user having a logical channel with the highest scheduling index value is selected, and resource calculation (transmission data length) is performed (S7 in FIG. 8). In this embodiment, only one user having a logical channel with the highest index value is selected. However, depending on the scheduling algorithm, a user having a high total of index values under the user or a plurality of users is selected. It is also assumed that.

  Next, based on the data length calculated in step S7, an RLC header is assigned to each logical channel, RLC PDUs are generated, all of them are combined, a MAC header is added, and a MAC PDU is generated ( In S8 of FIG. 8, pre-coding processing such as CRC addition and segmentation is performed on the MAC PDU (S9).

  FIG. 9 is a time chart of downlink processing, and shows a time chart of RLC MAC encoding pre-processing for a user of 3 sectors by using four processing units (25 Mbps PU). The processing time calculation condition described in FIG. 9 is 133 (users) per sector because the number of users accommodated per processing unit is 400 (3 sectors / unit), and the other conditions are B in FIG. . Is equivalent to the example. The total processing time is 403 μs, and each processing time (μs) is described for each time-divided block.

  As shown in FIGS. 9a to 9d, scheduling for sector 1 is executed at PU1, PU3, PU4 at the timing of a1, c1, d1, and then scheduling for sector 2 is performed at PU1, PU2, PU4. This is executed at the timing of d2, and subsequently, at the timings of scheduling a3, b2, c2, and d3 for the sector 3 in PU1 to PU4. During the time when the scheduling process is not executed, the processes shown in e to i of FIG. 9 are executed for the users in each sector in the PU1 to PU4. That is, e RLC SDU conversion (PU1 processing) is executed at the timing of e1 (sector 1), e2 (sector 2), and e3 (sector 3), and f RLC ARQ (PU2 processing) is f1, f2 , F3. Similarly, for each sector 1-3, g resource allocation (PU3 processing) is at timings g1-g3, h MAC PDU (PU3 processing) is at timings h1-h3, and i is not encoded. Processing (processing of PU4) is executed at timings i1 to i3.

  This is because the processing delay of scheduling differs depending on the sector, but what is processed in parallel with the scheduling processing differs depending on the sector. Specifically, in sector 1, only the RLC ARQ process is performed in parallel with the scheduling process, whereas in sector 3, all the processes other than the RLC SDU generation process are performed in parallel and allocated at the time allocated for scheduling. There is a difference. It can be seen that the processing load of all PUs is made uniform and the scheduling processing time is shortened by performing the above-described user allocation according to the processing load taking the parallel execution status into consideration.

  FIG. 10 is a time chart of downlink processing under different conditions, in which the data transmission rate is 50 Mbps and 2 sectors. The conditions other than the frequency and the number of sectors are the same as those in FIG.

  In the case of 50 Mbps, 2 sectors, the total transmission rate is 1.33 times that of 25 Mbps, 3 sectors, and the opportunity for parallel processing between different sectors is reduced. Although the processing time increases (in the example of FIG. 10, the total processing time is 466 μs), it is about 1.15 times that of the 25 Mbps, 3 sector case of FIG. 9, and the processing time is almost uniformized. It can be said that. That is, according to the present invention, even if the sector / band configuration is different, the processing load is equalized. Therefore, the present invention is a flexible method that can cope with various sector / band configurations without increasing the number of parts. It can be said that there is.

  FIG. 11 is an explanatory diagram of the effect of the present invention. FIG. 6 is a comparison diagram of the number of users that can be accommodated when the present invention is used and when it is not used. A. The horizontal axis represents the number of sectors, and the vertical axis represents the number of users / card. A. of FIG. The calculation conditions for the number of users that can be accommodated are shown in FIG. Shown in However, the numerical value of this calculation condition is an example, and since the amount of processing and device performance vary depending on the adopted device and design method, the number of accommodated users varies, but the case of using the present invention and the case of not using it The ratio of accommodation numbers remains the same.

  The present invention can be used in a radio base station in a high-speed mobile communication system, but can also be used in a fixed communication apparatus having a scheduler function, a termination function for a plurality of lines, and a code rotation / decoding function. .

It is a principle explanatory view of the present invention. It is an example of composition of the present invention. It is a figure which shows the functional block in a RLC / MAC encoding pre-processing unit. It is a figure which shows the processing flow of an Example. It is a figure which shows the example of the timing chart of user allocation prohibition area | region calculation by multi PU (processing unit). It is a figure which shows the flowchart of user allocation prohibition area | region calculation. It is a figure which shows the example of the timing chart of the user allocation by multi-PU which considered the allocation prohibition area | region. It is a figure which shows the processing flow of user allocation. It is a figure which shows the time chart of a downlink process. It is a figure which shows the time chart of the downstream process in different conditions. It is explanatory drawing of the effect by this invention. It is a figure which shows the structure of a mobile communication system. It is explanatory drawing of the radio channel used for HSDPA. It is a figure which shows the structural example of an HSDPA system. It is a figure which shows the protocol stack of LTE layer 2. FIG. It is explanatory drawing of a data format. It is a figure which shows the procedure of a channel encoding process. It is a figure which shows the structure of a prior art example.

Explanation of symbols

10 Downstream processing unit 10a Downstream RLC / MAC pre-coding processing unit (PU)
10b Buffer 10c Downstream coding processing unit (PU)
11 Upstream processing unit 11a Upstream decoding RLC / MAC processing unit (PU)
11b buffer

Claims (4)

In a communication processing method in a radio base station of a mobile communication system that transmits data to a mobile terminal via a radio line,
A radio base station that transmits data to the mobile terminal selects a mobile station that transmits data based on channel quality information, and has a scheduler function in which a processing amount is proportional to a transmission data amount and the number of users that determine a modulation method , The same processing unit has a line termination processing function in which the amount of processing for generating data by terminating data transmitted from the core network side is proportional to the data rate .
A communication processing method in a radio base station, wherein control is performed by switching and executing the scheduler function and the line termination processing function in a preset time domain. In claim 1,
The radio base station has an encoding / decoding processing function in which the processing amount is proportional to a data rate in the processing unit, and the encoding / decoding processing is set in advance together with the scheduler function and the line termination processing function, respectively. A communication processing method in a radio base station, which is executed by switching in the time domain. In either claim 1 or 2,
A communication processing method in a radio base station, wherein the processing unit is constituted by a plurality of processing units, and user allocation is performed so as to equalize processing load among the plurality of processing units. In claim 1,
A communication process in a radio base station , wherein a process proportional to the number of users is performed with a remaining processing load of the processing unit after initially assigning a line termination processing function in which the processing amount is proportional to a data rate method.

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