JP5114360B2 - Base station apparatus and radio channel allocation method - Google Patents

Description

  The present invention relates to a base station apparatus and a radio channel assignment method, and in particular, a base station apparatus that communicates with each of a plurality of mobile station apparatuses using at least one of a plurality of radio channels belonging to a predetermined time segment, and the radio channel thereof It relates to the allocation method.

  In some mobile communication systems, two or more types of timing (hereinafter referred to as “access timing”) from when a mobile station receives a radio channel assignment from a base station until the mobile station is used are defined. is there.

  For example, in the next generation personal handy-phone system (XG-PHS) defined in Non-Patent Document 1, a mobile station receives information called a MAP indicating a radio channel assignment from a base station and then the MAP. Two types of timings until communication is performed using the communication channel indicated by are defined.

FIG. 11 is a diagram for explaining two types of access timing (access timing 1 and access timing 2) defined in Non-Patent Document 1. In the next-generation PHS, a mobile station with high processing performance is divided into access timing 1, and as shown in FIG. In the next frame, EXCH (Extra Channel: one of communication channels) and ANCH indicated by the MAP are used. On the other hand, the mobile station with low processing performance is divided into access timing 2 and uses the EXCH and ANCH indicated by the MAP in the frame after the frame in which the MAP is received, as shown in FIG.
“ARIB STD-T95“ OFDMA / TDMA TDD Broadband Wireless Access System (Next Generation PHS) ARIB STANDARD ”1.0 Edition”, December 12, 2007, Radio Industries Association of Japan

  However, in the above mobile communication system, when a base station assigns a plurality of radio channels belonging to a certain time segment to a plurality of mobile stations, a radio channel assigned to a mobile station with a later access timing is assigned before a mobile station with an earlier access timing. Therefore, there are cases where a sufficient number of radio channels cannot be allocated to a mobile station with early access timing.

  For example, in the next-generation PHS, as shown in FIG. 12, when a base station allocates a plurality of radio channels belonging to a frame surrounded by a wavy line to a plurality of mobile stations, the base station is classified into access timing 2 (access The radio channel to be allocated to the mobile station (late timing) must be determined one frame ahead of the mobile station classified as access timing 1 (early access timing). For this reason, when the base station assigns all of the plurality of radio channels belonging to the frame surrounded by the wavy line to the mobile station classified by the access timing 2, the radio channel can be assigned to the mobile station classified by the access timing 1. It becomes impossible.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a base station apparatus and a radio channel allocation method capable of reducing a bias of radio channel allocation due to a difference in access timing between mobile station apparatuses. And

  In order to solve the above problems, a base station apparatus according to the present invention is a base station apparatus that communicates with each of a plurality of mobile station apparatuses using at least one of a plurality of radio channels belonging to a predetermined time segment. A mobile station apparatus having a later access timing than the other mobile station apparatuses after the radio channel is allocated by the base station apparatus to the use of the allocated radio channel among the plurality of mobile station apparatuses An access timing determination means for determining whether or not a mobile station apparatus with a slow access timing is included in the plurality of mobile station apparatuses, and a radio channel to be allocated to the mobile station apparatus with a slow access timing Radio channel allocating means for allocating at least a part of the remaining radio channels to the other mobile station apparatus Characterized in that it comprises a.

  The base station apparatus according to the present invention provides access timing when a plurality of mobile station apparatuses that share a plurality of radio channels belonging to a predetermined time segment include mobile station apparatuses whose access timing is later than other mobile station apparatuses. The number of radio channels allocated to a mobile station apparatus with a slower speed is limited. For this reason, according to the present invention, it is possible to reduce the bias of radio channel assignment due to the difference in access timing between mobile station apparatuses.

  In one aspect of the present invention, the radio channel allocating means allocates to the mobile station apparatus having a later access timing based on the number of mobile station apparatuses having a later access timing and the number of the other mobile station apparatuses. Limit the number of radio channels. According to this aspect, radio channels can be allocated fairly to mobile station apparatuses with early access timing and mobile station apparatuses with late access timing.

  Further, in one aspect of the present invention, the radio channel allocating unit is configured to allow the mobile station apparatus with a slow access timing based on a communication type of the mobile station apparatus with a slow access timing and a communication type of the other mobile station apparatus. Limit the number of radio channels allocated to. According to this aspect, a radio channel can be allocated fairly to a mobile station apparatus with early access timing and a mobile station apparatus with late access timing.

  Also, in one aspect of the present invention, the radio channel allocating unit is configured such that the mobile station apparatus with a slow access timing is based on a communication performance of a mobile station apparatus with a slow access timing and a communication performance of the other mobile station apparatus. Limit the number of radio channels allocated to. According to this aspect, radio channels can be allocated fairly to mobile station apparatuses with early access timing and mobile station apparatuses with late access timing.

  The radio channel assignment method according to the present invention is a radio channel assignment method for a base station apparatus that communicates with each of a plurality of mobile station apparatuses using at least one of a plurality of radio channels belonging to a predetermined time segment. A mobile station apparatus having a later access timing than the other mobile station apparatuses after the radio channel is allocated by the base station apparatus to the use of the allocated radio channel among the plurality of mobile station apparatuses And the number of radio channels to be allocated to the mobile station device having a slow access timing when the mobile station device having a slow access timing is included in the plurality of mobile station devices. Restricting and allocating at least a part of the remaining radio channel to the other mobile station device. To.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of a mobile communication system 10 according to an embodiment of the present invention. As shown in the figure, the mobile communication system 10 includes a base station 12 and a plurality of mobile stations 14 (only mobile stations 14-1 to 14-4 are shown here). The mobile communication system 10 is a next-generation PHS that complies with the standard described in Non-Patent Document 1 described above, and the base station 12 includes an OFDMA (Orthogonal Frequency Division Multiple Access) system and a TDMA / TDD (Time Division Multiple Access / Time Division Duplex: Time-division multiple access / time-division two-way communication) multiplex communication with a plurality of mobile stations 14 is performed.

  FIG. 2 is a diagram illustrating an example of a frame configuration of the next generation PHS. As shown in the figure, in the next-generation PHS, 1 TDMA frame (5 ms) is equally divided into 8 time slots, of which the first 4 slots (2.5 ms) are uplink (from the mobile station 14 to the base station). 4 slots (2.5 ms) in the latter half are allocated for the downlink (radio transmission path in the direction from the base station 12 to the mobile station 14) for the radio transmission path in the direction toward the station 12. Each time slot defines, for example, six subchannels by OFDMA.

  The minimum unit of the radio channel used for communication between the base station 12 and the mobile station 14 is called PRU (Physical Resource Unit), and one of the time slots by TDMA / TDD and the subchannel by OFDMA. It is specified by any combination. The 24 PRUs defined for the uplink and the 24 PRUs defined for the downlink are in pairs, and a pair of PRUs have the same ANCH (one dedicated control channel). Alternatively, the same EXCH (one of communication channels) is assigned.

  In the next-generation PHS, the base station 12 determines PRU allocation for each frame, and transmits information called MAP indicating the determined PRU allocation to each mobile station 14. Further, as described above, in the next-generation PHS, two types of timing (access timing) from when the mobile station 14 receives a MAP from the base station 12 until it communicates using the PRU indicated by the MAP are defined. (See FIG. 11). That is, the mobile station 14 with high processing performance is divided into access timing 1 and uses the EXCH and ANCH indicated by the MAP in the next frame after the MAP is received via the ANCH. On the other hand, the mobile station 14 with low processing performance is classified into access timing 2 and uses the EXCH and ANCH indicated by the MAP in the frame after the frame in which the MAP is received.

  For this reason, when the base station 12 assigns 24 sets of PRUs belonging to one frame to a plurality of mobile stations 14, the PRU assigned to the mobile station 14 divided into access timing 2 (slow access timing) is assigned to the access timing 1. It is necessary to determine and notify only one frame ahead of the mobile station 14 to be classified (early access timing) (see FIG. 12).

  The base station 12 according to the present embodiment includes a mobile station 14 that is divided into access timings 1 and a mobile station 14 that is divided into access timings 2 among a plurality of mobile stations 14 to which 24 sets of PRUs belonging to one frame are assigned. When both of the stations 14 are included, the number of PRUs allocated to the mobile stations 14 classified in the access timing 2 is limited, thereby securing the PRUs allocated to the mobile stations 14 classified in the access timing 1. For this reason, it becomes possible to reduce the bias of PRU allocation due to the difference in access timing between the mobile stations 14.

  Below, the structure with which the base station 12 is provided in order to implement | achieve the said process is demonstrated. FIG. 3 is a functional block diagram of the base station 12. As shown in the figure, the base station 12 includes an antenna 20, an RF (Radio Frequency) unit 22, a BB (Base Band) unit 24, a modulation unit 26, a demodulation unit 28, a storage unit 30, and a radio control unit 32. Consists of.

  The antenna 20 receives a radio signal and outputs the received radio signal to the RF unit 22. Further, the antenna 20 transmits a radio signal supplied from the RF unit 22 to the mobile station 14.

  The RF unit 22 includes a low noise amplifier, a power amplifier, a frequency conversion circuit, a band pass filter, an A / D converter, and a D / A converter. The RF unit 22 amplifies the radio signal input from the antenna 20 with a low noise amplifier, down-converts it to an intermediate frequency signal, and outputs the digitally converted signal to the BB unit 24. The RF unit 22 converts the digital signal input from the BB unit 24 into an analog signal, up-converts the signal to a radio signal, amplifies the signal to a transmission output level with a power amplifier, and supplies the signal to the antenna 20.

  The BB unit 24 includes an FFT (Fast Fourier Transform) unit, an IFFT (Inverse Fast Fourier Transform) unit, a serial-parallel converter, and a parallel-serial converter. The BB unit 24 performs GI (Guard Interval) removal, serial parallel conversion, discrete Fourier transform, and the like on the digital signal input from the RF unit 22, and outputs each subcarrier component of the obtained complex symbol sequence. After grouping for each subchannel, a complex symbol sequence further grouped for each mobile station 14 (for each user) is output to the demodulator 28. In addition, the BB unit 24 performs serial-parallel conversion, inverse discrete Fourier transform, parallel-serial conversion, addition of GI, and the like on the complex symbol sequence for each mobile station 14 input from the modulation unit 26, and outputs the obtained digital signal. Output to the RF unit 22.

  The modulation unit 26 performs symbol mapping (assignment of amplitude and phase) according to the modulation scheme specified by the radio control unit 32 on the transmission data to each mobile station 14 input from the radio control unit 32, The obtained complex symbol sequence for each mobile station 14 is output to the BB unit 24.

  The demodulator 28 decodes the received data corresponding to the symbol modulation scheme from the complex symbol sequence for each mobile station 14 input from the BB unit 24, and outputs the decoded received data to the radio controller 32.

  The storage unit 30 is configured by, for example, a semiconductor memory element, and stores various control programs, parameters, tables, and the like used by the wireless control unit 32.

  The radio control unit 32 includes, for example, a CPU and a program for controlling the operation of the CPU, and functionally includes a radio quality measurement unit 34, an access timing management unit 36, and a radio channel allocation unit 38.

  The radio quality measurement unit 34 measures the radio quality of each PRU as needed, and updates the radio quality management table (see FIG. 4) in the storage unit 30 that manages the radio quality of each PRU. The radio quality of each PRU measured by the radio quality measuring unit 34 includes the interference wave level detected by each PRU and the D / U ratio (Disire to Undesire radio: desired wave) of the radio signal received via each PRU. Level to interference wave level).

  The access timing management unit 36 identifies the access timing of each mobile station 14 communicating with the base station 12, and is divided into the number and ratio of the mobile stations 14 classified into access timing 1 and the access timing 2. The access timing management table of the storage unit 30 that manages the number and ratio of the mobile stations 14 is updated. For example, when the number of mobile stations 14 classified as access timing 1 is 1 and the number of mobile stations 14 classified as access timing 2 is 3, the access timing management table is in the state shown in FIG. Become.

  Further, the access timing management unit 36 determines the PRU in the frame based on the access timing management table stored in the storage unit 30 before the radio channel allocation unit 38 determines the allocation of 24 sets of PRUs belonging to one frame. It is determined whether or not both of the mobile stations 14 classified as the access timing 1 and the mobile stations 14 classified as the access timing 2 are included in the plurality of mobile stations 14 to be allocated. Notify the channel allocation unit 38.

  The radio channel allocation unit 38 determines the PRU allocation priority based on the radio quality management table stored in the storage unit 30, and allocates the PRU to each mobile station 14 based on the determined priority. For example, the radio channel allocation unit 38 gives a higher priority to a PRU having a higher radio quality.

  Here, when only a mobile station 14 classified into access timing 1 (early access timing) is included in the plurality of mobile stations 14 to be assigned with PRU, the radio channel allocating unit 38 does not change the mobile station as usual. The PRU to be assigned to the mobile station 14 divided into the access timing 1 is determined without considering the difference in access timing between the 14. In addition, when only a mobile station 14 that is classified into access timing 2 (slow access timing) is included in the plurality of mobile stations 14 that are subject to PRU allocation, the radio channel allocation unit 38 moves as usual. The PRU to be assigned to the mobile station 14 divided into the access timing 2 is determined without considering the difference in access timing between the stations 14.

  On the other hand, when both of the mobile stations 14 classified as the access timing 1 and the mobile stations 14 classified as the access timing 2 are included in the plurality of mobile stations 14 subject to PRU allocation, the radio channel allocation unit 38 The number of PRUs allocated to the mobile stations 14 classified at the access timing 2 is limited, and the remaining PRUs are allocated to other mobile stations 14, that is, the mobile stations 14 classified at the access timing 1. Thereby, the bias of PRU allocation due to the difference in access timing between the mobile stations 14 is reduced.

  The radio channel allocating unit 38 is divided into the number of mobile stations 14 divided into access timing 1 and the access timing 2 when limiting the number of PRUs assigned to the mobile stations 14 divided into access timing 2. Based on the number of mobile stations 14, the number of PRUs allocated to the mobile stations 14 classified at access timing 2 may be limited. In this way, PRUs are allocated fairly to the mobile station 14 classified at the access timing 1 and the mobile station 14 classified at the access timing 2.

  In addition, when limiting the number of PRUs assigned to the mobile station 14 that is divided into access timing 2, the radio channel allocating unit 38 is divided into the communication type of the mobile station 14 that is divided into access timing 1 and the access timing 2. The number of PRUs allocated to the mobile station 14 classified at the access timing 2 may be limited based on the communication type of the mobile station 14. The communication types here include application types such as VoIP (Voice over IP) that requires real-time performance and FTP (File Transfer Protocol) that does not require real-time performance, high-speed communication plans with high maximum transmission rates, and maximum transmission rates. A contract type set for each mobile station 14 such as a low-speed communication plan with a low level is included.

  In addition, when limiting the number of PRUs allocated to the mobile station 14 that is classified at the access timing 2, the radio channel allocation unit 38 is classified into the communication performance of the mobile station 14 that is classified at the access timing 1 and the access timing 2. The number of PRUs allocated to the mobile station 14 classified at the access timing 2 may be limited based on the communication performance of the mobile station 14. The communication performance here includes the total amount of communication data transmitted from the start of communication to that time, the occurrence frequency or occurrence cycle of communication data, and the like.

  Here, in the case where both of the mobile stations 14 classified into the access timing 1 and the mobile stations 14 classified into the access timing 2 are included in the plurality of mobile stations 14 targeted for PRU allocation, the radio channel allocation unit An example of a process in which 38 assigns a PRU to each mobile station 14 will be described.

  First, the radio channel allocation unit 38 determines the PRU allocation priority based on the radio quality management table stored in the storage unit 30. Next, the radio channel allocating unit 38 determines the number of mobile stations 14 classified into access timing 1 and the number of mobile stations 14 classified into access timing 2 from the radio quality management table stored in the storage unit 30. get.

  Here, the PRU allocation priority determined by the radio channel allocation unit 38 is in the state shown in FIG. 6, and the access timing management table stored in the storage unit 30 is divided into the status shown in FIG. If the number of mobile stations 14 to be assigned is 1 and the number of mobile stations 14 to be divided into access timings 2 is 3), the radio channel allocation unit 38 is divided into access timings 2 as shown in FIG. The number of PRUs assigned to the three mobile stations 14 is limited to 12 sets, and 4 sets of PRUs except the 8 sets of PRUs that cannot be used due to poor radio quality are classified as access timing 1 among the remaining PRUs. Assigned to the mobile station 14. That is, the radio channel allocating unit 38 allocates 3/4 (75%) of the 16 available PRUs to the three mobile stations 14 classified into the access timing 2 and the remaining 1/4 (25%). Are assigned to one mobile station 14 that is divided into access timings 1.

  If the PRU allocation priority determined by the radio channel allocating unit 38 is in the state shown in FIG. 8 and the access timing management table stored in the storage unit 30 is in the state shown in FIG. For example, as shown in FIG. 9, the unit 38 limits the number of PRUs allocated to the three mobile stations 14 divided into the access timing 2 to 12 sets, and among the remaining PRUs, the 8 sets cannot be used due to poor radio quality. 4 sets of PRUs except for the PRU are allocated to one mobile station 14 that is divided into access timings 1.

  Next, the operation of the base station 12 will be described. FIG. 10 is a flowchart showing an example of the PRU allocation process executed in the base station 12 every frame.

  As shown in the figure, the base station 12 measures the radio quality of each PRU by carrier sense (S100). Next, the base station 12 reads the number of mobile stations 14 classified into access timing 1 and the number of mobile stations 14 classified into access timing 2 from the storage unit 30, and calculates the ratio thereof (S102). Then, based on the radio quality of each PRU acquired in S100 and the ratio calculated in S102, the base station 12 determines whether the mobile station 14 classified into access timing 1 and the mobile station 14 classified into access timing 2 The number of PRUs of the next frame allocated to each is determined (S104).

  After that, the base station 12 determines the PRU of the next frame to be allocated to the mobile station 14 classified in the access timing 1 based on the determination result of S104 executed in the previous frame (S106). MAP indicating the PRU allocation is notified to the mobile station 14 classified at the access timing 1 (S108). Further, the base station 12 determines the PRU of the next frame to be allocated to the mobile station 14 classified at the access timing 2 based on the determination result of S104 executed in this frame (S110), and the determined next frame MAP indicating the allocation of the PRU is notified to the mobile station 14 classified at the access timing 2 (S112).

  Here, a processing flow for limiting the number of PRUs allocated to each mobile station 14 based on the number of mobile stations 14 classified into access timing 1 and the number of mobile stations 14 classified into access timing 2 is shown here. Although shown, the number of PRUs assigned to each mobile station 14 may be limited based on at least one of the number of mobile stations 14 classified by each access timing, communication type, and communication performance.

  According to the embodiment described above, the mobile stations 14 classified into the access timing 1 and the mobile stations classified into the access timing 2 among the plurality of mobile stations 14 to which 24 sets of PRUs belonging to one frame are assigned. 14 is included, the base station 12 secures a PRU to be allocated to the mobile station 14 classified in the access timing 1 by limiting the number of PRUs allocated to the mobile station 14 classified in the access timing 2. To do. For this reason, the bias of PRU allocation due to the difference in access timing between the mobile stations 14 can be reduced.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible. For example, in the above description, the example in which the present invention is applied to the base station of the next generation PHS has been shown. However, the present invention can be widely applied to base stations of mobile communication systems in which two or more types of access timings are defined. .

1 is a configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a figure which shows the frame structure of next generation PHS. It is a functional block diagram of the base station which concerns on embodiment of this invention. It is a figure which shows an example of the radio | wireless quality management table memorize | stored in a memory | storage part. It is a figure which shows an example of the access timing management table memorize | stored in a memory | storage part. It is a figure which shows an example of the allocation priority of PRU based on the radio | wireless quality of each PRU. It is a figure which shows the example of allocation of PRU. It is a figure which shows an example of the allocation priority of PRU based on the radio | wireless quality of each PRU. It is a figure which shows the example of allocation of PRU. It is a flowchart which shows an example of the PRU allocation process in the base station which concerns on embodiment of this invention. It is a figure explaining two types of access timing (access timing 1 and access timing 2) defined in the nonpatent literature 1. FIG. It is a figure which shows the timing which determines the radio channel allocated to the mobile station divided into each of the access timing 1 and the access timing 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Mobile communication system, 12 Base station, 14 Mobile station, 20 Antenna, 22 RF part, 24 BB part, 26 Modulation part, 28 Demodulation part, 30 Storage part, 32 Radio control part, 34 Radio quality measurement part, 36 Access timing Management unit, 38 radio channel allocation unit.

Claims (5)

A base station device that communicates with each of a plurality of mobile station devices using at least one of a plurality of radio channels belonging to a predetermined time segment,
Among the plurality of mobile station apparatuses, there is a mobile station apparatus whose access timing, which is a timing from when a radio channel is allocated by the base station apparatus to when the allocated radio channel is used, is slower than other mobile station apparatuses. Access timing determination means for determining whether or not included,
When the mobile station apparatus with a slow access timing is included in the plurality of mobile station apparatuses, the number of radio channels allocated to the mobile station apparatus with a slow access timing is limited, and at least a part of the remaining radio channels is Radio channel allocating means for allocating to the other mobile station device;
A base station apparatus comprising: The base station apparatus according to claim 1,
The radio channel allocating unit limits the number of radio channels to be allocated to the mobile station apparatus having a slow access timing based on the number of mobile station apparatuses having a slow access timing and the number of the other mobile station apparatuses.
A base station apparatus. In the base station apparatus according to claim 1 or 2,
The radio channel allocating unit limits the number of radio channels allocated to the mobile station apparatus having the later access timing based on the communication type of the mobile station apparatus having the later access timing and the communication type of the other mobile station apparatus. ,
A base station apparatus. In the base station apparatus in any one of Claim 1 to 3,
The radio channel allocating unit limits the number of radio channels allocated to the mobile station apparatus having the later access timing based on the communication performance of the mobile station apparatus having the later access timing and the communication performance of the other mobile station apparatus. ,
A base station apparatus. A radio channel allocation method of a base station apparatus that communicates with each of a plurality of mobile station apparatuses using at least one of a plurality of radio channels belonging to a predetermined time segment,
Among the plurality of mobile station apparatuses, there is a mobile station apparatus whose access timing, which is a timing from when a radio channel is allocated by the base station apparatus to when the allocated radio channel is used, is slower than other mobile station apparatuses. Determining whether it is included;
When the mobile station apparatus with a slow access timing is included in the plurality of mobile station apparatuses, the number of radio channels allocated to the mobile station apparatus with a slow access timing is limited, and at least a part of the remaining radio channels is Assigning to the other mobile station device;
A radio channel assignment method comprising:

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