WO2009110164A1 - Communication method and base station device using the same - Google Patents

Abstract

An acquiring section (50) acquires qualities of respective channels by a frame formed by a plurality of channels. An allocating section (52) allocates at least two channels having the qualities within a certain range to a terminal device, based on the acquired qualities. Sections from an RF section (20) to an IF section (26) execute communication with the terminal device by at least the allocated two channels.

Description

COMMUNICATION METHOD AND BASE STATION DEVICE USING THE SAME

The present invention relates to communication technology, and more particularly, to a communication method for communicating with a terminal device in a channel assigned to the terminal device, and a base station device using the communication method.

In a wireless communication system, a base station device may connect a plurality of terminal devices. One of the forms when the base station apparatus performs a plurality of terminal apparatuses is TDMA (Time Division Multiple Access) / TDD (Time Division Duplex). In TDMA / TDD, a frame is formed by a plurality of time slots, and a plurality of frames are continuously arranged. Further, some of the plurality of time slots included in one frame are used for the uplink, and the remaining time slots are used for the downlink. In such TDMA / TDD, for example, the number of time slots used for uplink in one frame and the number of time slots used for downlink depend on the traffic volume. It is set (for example, refer to Patent Document 1).
JP-A-8-186533

Generally, effective use of limited frequency resources is desired in wireless communication. In particular, as the communication speed increases, the demand is further increased. One technique for meeting this requirement is the OFDMA (Orthogonal Frequency Division Multiple Access) system, which can be combined with the TDMA / TDD described above. OFDMA is a technique for frequency-multiplexing a plurality of terminal devices using OFDM. Therefore, in a combination of OFDMA and TDMA (hereinafter, such a combination is also simply referred to as “OFDMA” and used without being distinguished from normal OFDMA), a plurality of subchannels defined in the frequency axis direction and time There are a plurality of time slots defined in the axial direction. Further, a combination of subchannels and time slots (hereinafter referred to as “burst”) is used for communication.

In such OFDMA, the base station apparatus periodically assigns a burst for communicating data to each terminal apparatus. Such burst allocation is called a “circuit switching system” and is suitable for communications in which transmission delay is to be reduced, such as a voice call. On the other hand, as in data communication, a small transmission delay is not required, but the amount of traffic may vary greatly. In the latter case, not the circuit switching method but the “random access method” in which the number of bursts allocated to the terminal device is changed in units of frames according to the traffic volume is suitable. In the random access method, a plurality of bursts may be assigned to a terminal device per frame. In addition, when allocating a plurality of bursts per frame to a terminal device, the communication speed for each of the plurality of bursts is set to a common value in order to simplify processing. Here, the communication speed is generally set according to communication quality such as the amount of interference. Therefore, if the communication quality for one burst is deteriorated, the communication speed for a plurality of bursts is reduced, and the bursts are not used effectively.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication technique for effectively allocating bursts when allocating a plurality of bursts per terminal to a terminal device.

In order to solve the above problems, a base station apparatus according to an aspect of the present invention is based on an acquisition unit that acquires the quality of each channel in a frame formed by a plurality of channels, and the quality acquired by the acquisition unit. An allocating unit that allocates at least two channels having a quality within a certain range to the terminal device, and a communication unit that performs communication with the terminal device using at least two channels allocated by the allocating unit.

Another aspect of the present invention is a communication method. The method includes a step of acquiring the quality of each channel in a frame formed by a plurality of channels, and a step of assigning at least two channels included in a certain range to the terminal device based on the acquired quality. And executing communication with the terminal device on at least two allocated channels.

It should be noted that an arbitrary combination of the above-described components and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, and the like are also effective as an aspect of the present invention.

According to the present invention, bursts can be effectively allocated when a plurality of bursts are allocated to a terminal device per frame.

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. It is a figure which shows the structure of the TDMA frame in the communication system of FIG. It is a figure which shows the structure of the OFDMA subchannel in the communication system of FIG. It is a figure which shows the structure of the subchannel block in the communication system of FIG. It is a figure which shows the structure of the control channel in the communication system of FIG. FIG. 2 is a sequence diagram showing a TCH synchronization establishment procedure in the communication system of FIG. 1. It is a figure which shows the structure of the base station apparatus of FIG. It is a figure which shows the outline | summary of the acquisition result by the acquisition part of FIG. It is a figure which shows the outline | summary of the conversion result by the conversion part of FIG. It is a flowchart which shows the allocation procedure by the base station apparatus of FIG.

Explanation of symbols

10 base station device, 12 terminal device, 20 RF unit, 22 modulation / demodulation unit, 24 baseband processing unit, 26 IF unit, 30 control unit, 50 acquisition unit, 52 allocation unit, 54 measurement unit, 56 reception unit, 58 conversion unit , 60 execution units, 100 communication systems.

Before describing the present invention specifically, an outline will be given first. Embodiments of the present invention relate to a communication system including a base station device and at least one terminal device. In the communication system, each time slot is formed by time-division multiplexing a plurality of time slots, and each time slot is formed by frequency-division multiplexing a plurality of subchannels. Each subchannel is formed by a multicarrier signal. Here, OFDM signals are used as multicarrier signals, and OFDMA is used as frequency division multiplexing. The base station apparatus performs communication with the plurality of terminal apparatuses by assigning each of the plurality of subchannels included in each time slot to the terminal apparatus.

Here, there are a plurality of types of data targeted for communication with a plurality of terminal devices. Further, the required communication speed and delay time differ depending on the type. For example, in the case of voice communication, a shorter delay time is generally required compared to data communication. In data communication, the communication speed varies depending on the content of data. Therefore, when a short delay time is required, it is preferable to periodically assign bursts as in the circuit switching method. For example, the base station apparatus periodically assigns bursts to each terminal apparatus at a frame period. On the other hand, when the circuit switching method is applied to a terminal device that does not require a short delay time, useless allocation occurs and it becomes difficult to follow changes in the data amount.

Therefore, in the case of data communication, the base station apparatus arbitrarily assigns bursts to each terminal apparatus as in the random access scheme. Hereinafter, in the random access scheme, a data channel to be allocated to a burst is referred to as “EDCH”. Also, in the random access scheme, control information related to EDCH (hereinafter referred to as “ECCH”) is generated for each frame. The ECCH includes information regarding a burst in which the EDCH is arranged, a communication speed of the EDCH, and the like. The base station apparatus periodically performs ECCH communication with each terminal apparatus. When the terminal device receives the ECCH, the terminal device recognizes the burst to which the EDCH is assigned by confirming the contents of the ECCH. As described above, in the random access method, when the communication speeds of a plurality of EDCHs included in one frame are set in common, there is a possibility that the burst may not be used effectively.

To cope with this, the base station apparatus according to the present embodiment acquires the quality for each of the assignable bursts in the frame. An example of quality is the amount of interference. Further, the base station apparatus estimates the expected communication speed for each burst based on the quality. As a result, the communication speed for each burst included in the frame is derived. Thereafter, the base station apparatus selects at least two bursts with the same communication speed for one terminal apparatus. Further, the base station apparatus allocates at least two selected bursts to the one terminal apparatus, and executes communication by EDCH in the allocated burst.

FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a first terminal device 12a, a second terminal device 12b, and a third terminal device 12c, which are collectively referred to as a base station device 10 and a terminal device 12.

The base station apparatus 10 connects the terminal apparatus 12 to one end via a wireless network, and connects a wired network (not shown) to the other end. Further, the terminal device 12 is connected to the base station device 10 via a wireless network. Since the base station apparatus 10 has a plurality of time slots and a plurality of subchannels, the base station apparatus 10 executes OFDMA by a plurality of subchannels while executing TDMA by the plurality of time slots. As described above, a unit combining time slots and subchannels is defined as a burst, and the base station apparatus 10 assigns a burst to each of the plurality of terminal apparatuses 12, thereby Execute communication. Specifically, the base station apparatus 10 defines any one of a plurality of subchannels as a control channel. Base station apparatus 10 periodically transmits a broadcast signal such as BCCH on the control channel.

The terminal device 12 recognizes the presence of the base station device 10 by receiving the BCCH and requests the base station device 10 for ranging. Further, the base station apparatus 10 responds to the ranging. Ranging is a process for correcting the frequency offset and timing offset of the terminal device 12, but since a known technique may be used for ranging, description thereof is omitted here. Thereafter, the terminal apparatus 12 transmits a burst allocation request signal to the base station apparatus 10, and the base station apparatus 10 allocates a burst to the terminal apparatus 12 in response to the received request signal. Here, there are two types of allocation rules in the communication system 100, which are a circuit switching system and a random access system.

Further, the base station apparatus 10 transmits information related to the burst allocated to the terminal apparatus 12, and the terminal apparatus 12 performs communication with the base station apparatus 10 while using the allocated burst. As a result, the data transmitted from the terminal device 12 is output to the wired network via the base station device 10 and finally received by a communication device (not shown) connected to the wired network. Data is also transmitted in the direction from the communication device to the terminal device 12. Here, the base station apparatus 10 allocates ECCH in units of frames to the terminal apparatus 12 that is executing the random access scheme. Further, the base station apparatus 10 allocates EDCH to the terminal apparatus 12. The number of EDCHs in a frame varies from frame to frame. Here, control information related to EDCH is included in ECCH. For example, bursts in a frame to which EDCH is allocated, communication speed for EDCH, and the like are included in ECCH. Details of these will be described later.

FIG. 2 shows the structure of a TDMA frame in the communication system 100. In the communication system 100, as in the second generation cordless telephone system, a frame is configured by four time slots for uplink communication and four time slots for downlink communication. Here, four time slots for uplink communication correspond to uplink subframes, and four time slots for downlink communication correspond to downlink subframes. Furthermore, the frames are continuously arranged. In the present embodiment, time slot allocation in uplink communication and time slot allocation in downlink communication are the same, and therefore only downlink communication may be described below for convenience of explanation.

FIG. 3 shows the configuration of the OFDMA subchannel in the communication system 100. In addition to the TDMA described so far, the base station apparatus 10 also applies OFDMA as shown in FIG. As a result, a plurality of terminal devices are assigned to one time slot. FIG. 3 shows the arrangement of time slots on the time axis in the direction of the horizontal axis, and the arrangement of subchannels on the frequency axis in the direction of the vertical axis. That is, multiplexing on the horizontal axis corresponds to TDMA, and multiplexing on the vertical axis corresponds to OFDMA. Here, the first time slot (shown as “T1” in the figure) to the fourth time slot (shown as “T4” in the figure) in one frame are included. For example, T1 to T4 in FIG. 3 correspond to the fifth to eighth time slots in FIG. 2, respectively.

Each time slot includes the first subchannel (indicated as “SC1” in the figure) to the 16th subchannel (indicated as “SC16” in the figure). In FIG. 3, the first subchannel is reserved as a control channel. In the figure, the first base station apparatus 10a (indicated as “CS1” in the figure) assigns a control signal to the first subchannel of the first time slot. That is, the frame configuration when focusing only on SC1 and a set of a plurality of frames correspond to the LCCH. In FIG. 3, the first terminal apparatus 12a is assigned to the second subchannel of the first time slot, and the second terminal apparatus 12b is assigned to the second subchannel to the fourth subchannel of the second time slot. Also, the third terminal apparatus 12c is allocated to the 16th subchannel of the third time slot, and the fourth terminal apparatus 12d is allocated to the 13th to 15th subchannels of the fourth time slot. Among these, the burst allocated to the first terminal apparatus 12a and the burst allocated to the third terminal apparatus 12c correspond to ECCH.

FIG. 4 shows a configuration of subchannel blocks in the communication system 100. The subchannel block corresponds to a radio channel specified by a time slot and a subchannel. The horizontal direction in FIG. 4 is a time axis, and the vertical direction is a frequency axis. The numbers “1” to “29” correspond to subcarrier numbers. In this way, the subchannel is configured by an OFDM multicarrier signal. In the figure, “TS” corresponds to a training symbol and includes known signals such as a synchronization detection symbol “STS” (not shown) and a transmission path characteristic estimation symbol “LTS”. “GS” corresponds to a guard symbol, and no effective signal is arranged here. “PS” corresponds to a pilot symbol and is configured by a known signal. “SS” corresponds to a signal symbol, and a control signal is arranged. “DS” corresponds to a data symbol and is data to be transmitted. “GT” corresponds to a guard time, and no effective signal is arranged.

FIG. 5 shows the configuration of the control channel in the communication system 100. The control channel is composed of a total of 24 channels of 4 BCCHs, 12 IRCHs, and 8 PCHs. Each of BCCH, IRCH, and PCH is composed of eight TDMA frames (hereinafter referred to as “frames”). One frame is configured as shown in FIG. In FIG. 5, for convenience, frames in which PCH, BCCH, and IRCH are arranged are also indicated as “PCH”, “BCCH”, and “IRCH”. As described above, a frame is divided into a plurality of time slots. Here, “PCH”, “BCCH” are used without distinguishing each of a time slot unit, a frame unit, and an 8-frame unit. ”And“ IRCH ”.

In the figure, “IRCH” is an initial ranging channel used for channel allocation. More specifically, “IRCH” includes “TCCH” and “IRCH”, and “TCCH” is an initial ranging request transmitted from the terminal apparatus 12 to the base station apparatus 10. Equivalent to. “IRCH” corresponds to a response to the initial ranging request. Therefore, “TCCH” is an uplink signal, and “IRCH” is a downlink signal (hereinafter, a combination of TCCH and IRCH is also referred to as IRCH, but is used without distinction from the case of IRCH alone. ). In addition, although the base station apparatus which received TCCH from a terminal device performs the ranging process, since the ranging process may be a well-known technique, description is abbreviate | omitted here.

The lower part of the figure shows the structure of each frame, which is shown in the same manner as in FIG. This corresponds to the frame configuration for SC1 in FIG. The first base station apparatus 10a in FIG. 1 intermittently transmits BCCH, IRCH, and PCH at intervals of 8 frames in a time slot (indicated as “CS1” in the figure) to which an LCCH is allocated among time slots constituting a frame. Send to. That is, the first base station apparatus 10a uses the fifth time slot of the first frame among the eight frames constituting the BCCH, and the fifth time slot of the first frame among the eight frames constituting the IRCH. Is used.

Further, the first base station apparatus 10a uses the fifth time slot of the first frame among the eight frames constituting the PCH. The second base station apparatus 10b shown in FIG. 1 uses the first base station apparatus 10a in the time slot of the next frame (the second frame in the figure) transmitted by the first base station apparatus 10a. BCCH, IRCH, and PCH are intermittently transmitted at intervals of 8 frames in the same time slot as the time slot (indicated as “CS2” in the figure) at the same position from the beginning of the frame. With such a configuration, it is possible to multiplex up to eight base station apparatuses and a maximum of 32 base station apparatuses for every four downlink time slots constituting the frame.

FIG. 6 is a sequence diagram showing a TCH synchronization establishment procedure in the communication system 100. This corresponds to a sequence diagram when the above-described circuit switching system is executed. The base station apparatus 10 stores the terminal number of the terminal apparatus 12, and transmits PCH together with other base station apparatuses belonging to the paging area (S100). The base station apparatus 10 transmits BCCH at a predetermined timing (S102). When the terminal device 12 that has received the PCH includes its own terminal number in the PCH, the base station device 10 is identified based on the BCCH, and then the source identification information is stored in the TCCH. To request initial initial ranging (S104). The TCCH is a signal defined for requesting initial ranging, and is defined as a plurality of types of waveform patterns. The base station apparatus 10 separates the transmission source identification information UID of the terminal apparatus 12 from the received TCCH, and allocates the terminal apparatus 12 to an empty TCH. The base station apparatus 10 stores the assigned TCH slot number and subchannel number in the IRCH and transmits the IR channel to the terminal apparatus 12, and notifies the terminal apparatus 12 of the TCH to be subjected to the second initial ranging (S106). The terminal device 12 stores the transmission source identification information in the TCCH, transmits it to the base station device 10 using the allocated initial ranging TCH, and requests the second initial ranging (S108).

The base station apparatus 10 performs a ranging process using the TCH assigned to the terminal apparatus 12, stores time alignment control, transmission output control, and SCCH transmission / reception timing in the RCH, transmits to the terminal apparatus 12, and transmits. Request correction of output or the like (S110). The terminal device 12 extracts the correction value requested from the base station device 10 from the received RCH, and corrects the transmission output and the like. Hereinafter, the above processing is collectively referred to as “ranging processing”. Next, radio resource allocation is requested to the base station apparatus 10 using the allocated initial ranging TCH (S112). The base station apparatus 10 performs an FEC decoding process on the radio resource allocation request message from the terminal apparatus 12 and then allocates an empty TCH to the terminal apparatus 12. Then, the slot number and subchannel number of the allocated TCH are stored in the SCCH and transmitted to the terminal device 12 (S114). Since the TCH synchronization is established through the steps up to here, the base station apparatus 10 and the terminal apparatus 12 transmit and receive data using the synchronized TCH (S116).

FIG. 7 shows the configuration of the base station apparatus 10. The base station apparatus 10 includes an RF unit 20, a modem unit 22, a baseband processing unit 24, an IF unit 26, and a control unit 30. The control unit 30 includes an acquisition unit 50 and an allocation unit 52, the acquisition unit 50 includes a measurement unit 54 and a reception unit 56, and the allocation unit 52 includes a conversion unit 58 and an execution unit 60.

The RF unit 20 performs frequency conversion on a radio frequency multicarrier signal received from a terminal device 12 (not shown) as a reception process to generate a baseband multicarrier signal. Here, the multicarrier signal is formed as shown in FIG. 3, and corresponds to the uplink time slot of FIG. Further, the RF unit 20 outputs a baseband multicarrier signal to the modem unit 22. In general, a baseband multicarrier signal is formed by an in-phase component and a quadrature component, and therefore should be transmitted by two signal lines. For the sake of clarity, a single signal line is used here. Only. The RF unit 20 also includes an AGC and an A / D conversion unit.

The RF unit 20 performs frequency conversion on the baseband multicarrier signal input from the modem unit 22 as a transmission process, and generates a radio frequency multicarrier signal. Further, the RF unit 20 transmits a radio frequency multicarrier signal. The RF unit 20 transmits a multicarrier signal while using the same radio frequency band as the received multicarrier signal. In other words, it is assumed that TDD is used as shown in FIG. The RF unit 20 also includes a PA (Power Amplifier) and a D / A conversion unit.

The modulation / demodulation unit 22 performs conversion from the time domain to the frequency domain by performing FFT on the baseband multicarrier signal input from the RF unit 20 as reception processing. The multicarrier signal converted into the frequency domain has components corresponding to each of a plurality of subcarriers as shown in FIGS. The modem unit 22 performs timing synchronization, that is, FFT window setting, and also deletes the guard interval. Since a known technique may be used for timing synchronization and the like, description thereof is omitted here. Further, the modem unit 22 demodulates the multicarrier signal converted into the frequency domain. Note that the channel characteristics are estimated for demodulation, but the channel characteristics are estimated in units of subcarriers. The modem unit 22 outputs the demodulated result to the baseband processing unit 24.

The modem unit 22 performs modulation on the multicarrier signal received from the baseband processing unit 24 as transmission processing. Further, the modem unit 22 performs conversion from the frequency domain to the time domain by executing IFFT on the modulated multicarrier signal. The modem unit 22 outputs the multicarrier signal converted into the time domain to the RF unit 20 as a baseband multicarrier signal. The modem unit 22 also adds a guard interval, but a description thereof is omitted here.

The baseband processing unit 24 receives the demodulation result from the modulation / demodulation unit 22 as a reception process, and separates the demodulation result into units of the terminal device 12. That is, the demodulation result is composed of a plurality of subchannels as shown in FIG. Therefore, when one subchannel is assigned to one terminal apparatus 12, the demodulation result includes signals from a plurality of terminal apparatuses 12. The baseband processing unit 24 separates such a demodulation result for each terminal device 12. The baseband processing unit 24 adds information for identifying the transmission source terminal device 12 and information for identifying the destination to the separated demodulation result, and outputs the result to the IF unit 26.

As a transmission process, the baseband processing unit 24 receives data from the IF unit 26 to the plurality of terminal devices 12, assigns the data to subchannels, and forms a multicarrier signal from the plurality of subchannels. That is, the baseband processing unit 24 forms a multicarrier signal composed of a plurality of subchannels as shown in FIG. Note that subchannels to which data is to be assigned are determined as shown in FIG. 3, and instructions relating to the subchannels are received from the control unit 30. The baseband processing unit 24 outputs the multicarrier signal to the modem unit 22.

The IF unit 26 outputs the demodulation result received from the baseband processing unit 24 to a wired network (not shown) as a reception process. The destination of the demodulation result is set based on information added to the demodulation result and information for identifying the destination. Here, the information for identifying the destination is indicated by, for example, an IP (Internet Protocol) address. Further, the IF unit 26 inputs data for the plurality of terminal devices 12 from a wired network (not shown) as a transmission process. The control unit 30 outputs the input data to the baseband processing unit 24.

The control unit 30 executes burst allocation to the terminal device 12, timing control of the base station device 10 as a whole, and the like. Burst assignment corresponds to assigning a combination of subchannels and time slots. As described above, the control unit 30 executes the circuit switching method and the random access method as burst allocation. For example, the control unit 30 executes a circuit switching method in response to a request from the terminal device 12. That is, the control unit 30 periodically assigns bursts to the terminal device 12 for the terminal device 12. For example, the burst included in the time slot of the frame period is allocated to the first terminal apparatus 12a. Note that bursts need only be allocated periodically, and are not limited to the frame period, but may be a period longer than the frame period or a period shorter than the frame period. .

Further, the control unit 30 executes the random access method in response to a request from another terminal device 12. That is, the control unit 30 changes the burst allocation to the terminal device 12 in units of frames. For example, the control unit 30 determines the number of bursts to be allocated while reflecting the amount of communication with the terminal device 12. The control unit 30 periodically allocates an ECCH to the terminal device 12, and includes information on the allocated burst in the ECCH. Here, the control unit 30 notifies the allocation of the ECCH when transmitting the SCCH. For this reason, the ECCH is regularly allocated as in the TCH in the circuit switching system.

The operation in the control unit 30 will be described in more detail. Here, as particularly related to the present embodiment, (1) operation at the time of new connection, (2) basic operation in the random access method, (3) The EDCH allocation operation will be described in order. Here, in order to clarify the explanation, processing for one terminal device 12 will be described.

(1) Operation at the time of new connection After the ranging process is completed, the control unit 30 wirelessly transmits from the RF unit 20 to the terminal unit 12 (not shown) that is not connected via the IF unit 26. A resource acquisition request SCCH is received. The control unit 30 allocates a burst to the terminal device 12 based on the radio resource acquisition request SCCH. At this time, for example, the radio resource acquisition request SCCH may include information indicating whether allocation by a circuit switching scheme or allocation by a random access scheme is desired. Based on the information, the control unit 30 determines assignment by a circuit switching method or assignment by a random access method. In either case, symmetrical burst allocation is performed for the uplink subframe and the downlink subframe. When executing the circuit switching method, the control unit 30 directly assigns a TCH, that is, a burst to include data, to the terminal device 12.

On the other hand, when executing the random access method, the control unit 30 directly assigns a burst including information on ECCH, that is, EDCH, to the terminal device 12. For this reason, the assignment of bursts to the EDCH is transmitted to the terminal device 12 via the ECCH. The control unit 30 transmits the result of TCH allocation in the circuit switching method or the result of ECCH allocation in the random access method as radio resource allocation SCCH from the IF unit 26 to the terminal device 12 (not shown) from the RF unit 20. A terminal device 12 (not shown) performs communication based on the contents of the radio resource allocation SCCH.

(2) Basic operation in random access method The control unit 30 determines a burst to be allocated to the EDCH in units of frames. Burst allocation for EDCH is performed for each of uplink EDCH and downlink EDCH. The allocation of bursts to EDCH will be described later. The control unit 30 stores burst allocation results for the uplink EDCH and downlink EDCH in the ECCH. The ECCH also includes information such as the communication speed for the EDCH. The communication speed is determined by the modulation method and the error correction coding rate.

Further, the ECCH includes ACK / NACK information for the past EDCH. Such ACK / NACK information is used for ARQ (Automatic Repeat Request) and HARQ, but the description is omitted here. Such ECCH corresponds to downlink ECCH, but uplink ECCH also exists in ECCH. The uplink ECCH is transmitted from a terminal device 12 (not shown), and includes communication speed information and ACK / NACK information on the EDCH. In addition, after notification of ECCH, communication by EDCH is performed between base station apparatus 10 and terminal apparatus 12 according to information included in ECCH.

(3) EDCH allocation operation The acquisition unit 50 acquires the quality of each burst in a frame formed by a plurality of bursts, as shown in FIGS. Specifically, the measurement unit 54 measures the quality of each burst included in the uplink subframe via the RF unit 20 through the IF unit 26. For example, the measurement unit 54 measures the interference power in each burst. In addition, since a well-known technique should just be used for the measurement of interference electric power, description is abbreviate | omitted here. In addition, the reception unit 56 receives the quality of each burst included in the downlink subframe from the terminal device 12 via the RF unit 20 through the IF unit 26.

In this case, the quality of each burst is measured in the terminal device 12. Again, interference power may be used as the quality. As a result of the above processing, the acquisition unit 50 acquires the interference power of each burst included in the uplink subframe and the interference power of each burst included in the downlink subframe. As described above, the former is measured at the base station apparatus 10, while the latter is measured at each terminal apparatus 12. For this reason, the former includes interference power corresponding to the number of bursts as one combination, while the latter includes the above-described combinations corresponding to the number of terminal devices 12.

FIG. 8 shows an outline of an acquisition result obtained by the acquisition unit 50. The vertical axis and horizontal axis in FIG. 8 are the same as in FIG. FIG. 8 corresponds to a measurement result in the measurement unit 54. As shown in the figure, the measurement result is not shown in the first time slot “T1”. However, this is excluded from the allocation target of the EDCH because the first time slot is used in the circuit switching system. It corresponds to that. The same applies to SC1, but this corresponds to the fact that the control channel is assigned to SC1, so that it is not subject to EDCH assignment. Moreover, ECCH is allocated to SC2 of the second time slot “T2”. In other bursts, representative values such as “C203” are stored. Returning to FIG.

The conversion unit 58 converts the interference power of each channel acquired by the acquisition unit 50 into an expected communication speed. For example, assuming that the received power of ECCH is the received power of EDCH, conversion section 58 derives the ratio of received power and interference power (hereinafter referred to as “CIR”). Further, the conversion unit 58 stores in advance a table in which CIR and communication speed are associated with each other. The conversion unit 58 converts the derived CIR into a communication speed while referring to the table. Also, the conversion unit 58 performs such conversion for each burst.

FIG. 9 shows an outline of the conversion result by the conversion unit 58. FIG. 9 is shown corresponding to FIG. Here, for the sake of clarity, it is assumed that the communication speed is determined only by the modulation scheme. Therefore, FIG. 9 shows the modulation scheme determined by the conversion unit 58 for each burst. Moreover, the same result is derived for each terminal apparatus 12 for the downlink. Returning to FIG.

The execution unit 60 selects at least two bursts whose communication speed is included in a certain range based on the communication speed of each burst converted by the conversion unit 58. Prior to this, the execution unit 60 receives a request for a communication speed per frame from an upper application layer (not shown). The communication speed per frame is derived by accumulating the communication speed in units of bursts by the burst allocated per frame. Here, the communication speed in burst units corresponds to the communication speed converted by the conversion unit 58. Hereinafter, the communication speed in burst units is simply referred to as “communication speed”, and the communication speed per frame is referred to as “total communication speed”. The execution unit 60 derives the number of bursts required when the communication speed is fixed to satisfy the received request.

For example, when the communication speed is “BPSK”, there are “x” pieces, and when the communication speed is “16QAM”, the number of bursts is derived. The execution unit 60 confirms for each communication speed whether or not the derived burst number can be secured while referring to the conversion result shown in FIG. At that time, the secured communication speed and burst are used for EDCH. When a desired number of bursts can be secured for a plurality of communication speeds, the execution unit 60 selects the highest communication speed. This is to effectively use frequency resources. If the desired number of bursts cannot be secured, the execution unit 60 executes the same processing including the one higher communication speed. As a result, the execution unit 60 assigns at least two bursts whose quality falls within a certain range to the EDCH based on the quality acquired by the acquisition unit 50.

In addition, when EDCH is allocated independently in each of the uplink subframe and the downlink subframe, the above process may be executed separately for each of the uplink subframe and the downlink subframe. However, when the EDCH is symmetrically allocated in each of the uplink subframe and the downlink subframe, the execution unit 60 considers both the burst in the uplink subframe and the burst in the downlink subframe, and Execute the process. For example, when it is necessary to secure 4 bursts in “16QAM”, the execution unit 60 reserves 4 bursts in the uplink subframe and whether it can secure 4 bursts in the uplink subframe. Check if you can.

When both can be secured, the execution unit 60 determines that a burst for “16QAM” has been secured. That is, the execution unit 60 performs at least two bursts included in the uplink subframe and at least two bursts included in the downlink subframe so that the burst allocation is symmetric between the uplink subframe and the downlink subframe. Are assigned to EDCH. As described above, the control unit 30 includes the allocation result in the execution unit 60 in the ECCH. Thereafter, the RF unit 20 to the IF unit 26 perform communication with the terminal device 12 using at least two EDCHs assigned by the execution unit 60.

This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it is realized by a program having a communication function loaded in the memory. Describes functional blocks realized by collaboration. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

The terminal device 12 shown in FIG. 1 is configured in the same manner as the base station device 10 shown in FIG. Differences in functions between the terminal apparatus 12 and the base station apparatus 10 exist in ranging processing, channel allocation, ECCH generation, and the like. Since these have already been described, description thereof is omitted here. Further, the terminal apparatus 12 measures interference power for a plurality of bursts included in the downlink subframe in response to the operation at the base station apparatus 10, and transmits the measurement result to the base station apparatus 10. Here, corresponding to the description of FIG. 7, the description will focus on the reception operation in the random access scheme.

The terminal device 12 periodically receives an ECCH assigned to a predetermined burst among frames formed by a plurality of bursts. The terminal device 12 grasps the burst position of the EDCH assigned in the future frame by confirming the contents of the ECCH. The terminal device 12 receives data on the assigned EDCH and transmits the data. Further, as described above, the terminal device 12 transmits the data reception result, for example, ACK included in the ECCH.

The operation of the communication system 100 configured as above will be described. FIG. 10 is a flowchart showing an allocation procedure by the base station apparatus 10. The execution unit 60 acquires the required overall communication speed (S200). Further, the execution unit 60 fixes the communication speed to a predetermined value (S202). For example, the execution unit 60 fixes the highest communication speed. The execution unit 60 derives the number of bursts based on the communication speed (S204). If the derived number of bursts cannot be secured (N in S206), the execution unit 60 changes the communication speed (Y in S208), changes it (S210), and returns to step 204. On the other hand, if the communication speed cannot be changed (N in S208), the execution unit 60 selects a communication speed close to the required overall communication speed (S212). Thereafter, or when the derived number of bursts can be secured (Y in S206), the execution unit 60 secures bursts and causes the control unit 30 to generate ECCH (S214). The control unit 30 transmits the ECCH via the IF unit 26, the baseband processing unit 24, the modem unit 22, and the RF unit 20 (S216). Thereafter, the RF unit 20 to the IF unit 26 perform communication with the terminal device 12 (S218).

According to the embodiment of the present invention, since at least two channels within a certain range of quality are allocated to the terminal device, the same communication speed is realized when a plurality of bursts are allocated to the terminal device per frame. it can. In addition, since the same communication speed is realized for a plurality of bursts, even when the same communication speed is applied to the plurality of bursts, a communication speed close to a realizable communication speed can be used. Further, since a communication speed close to a realizable communication speed is used, bursts can be allocated effectively. In addition, since the quality in the uplink subframe and the downlink subframe is considered, bursts in the uplink subframe and the downlink subframe can be assigned symmetrically. After converting the quality to the expected communication speed, at least two bursts whose communication speed is included in a certain range are selected, so that the processing can be simplified.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

In the embodiment of the present invention, the execution unit 60 prioritizes the highest communication speed when determining burst allocation. However, not limited to this, for example, the execution unit 60 may prioritize a communication speed close to the communication speed used so far. According to this modification, a change in communication speed between frames is reduced, and communication stability can be improved.

In the embodiment of the present invention, the acquisition unit 50 and the allocation unit 52 execute the allocation of bursts to the EDCH. However, the present invention is not limited to this. For example, the acquisition unit 50 and the allocation unit 52 may execute burst allocation to a circuit-switched TCH. At that time, the acquisition unit 50 and the allocation unit 52 execute the above-described processing only at the time of connection, not in units of frames. According to this modification, bursts can be effectively allocated even when the circuit switching method is executed.

According to the present invention, bursts can be effectively allocated when a plurality of bursts are allocated to a terminal device per frame.

Claims (4)

An acquisition unit for acquiring the quality of each channel in a frame formed by a plurality of channels;
Based on the quality acquired in the acquisition unit, an allocation unit that allocates at least two channels whose quality is included in a certain range to a terminal device;
A communication unit that performs communication with the terminal device on at least two channels allocated by the allocation unit;
A base station apparatus comprising: A frame is formed by an uplink subframe and a downlink subframe,
The acquisition unit
A measurement unit for measuring the quality of each channel included in the uplink subframe;
A reception unit that receives the quality of each channel included in the downlink subframe from the terminal device;
The allocating unit sets the uplink subframe so that channel allocation is symmetric between the uplink subframe and the downlink subframe based on the quality measured by the measurement unit and the quality received by the reception unit. The base station apparatus according to claim 1, wherein at least two channels included and at least two channels included in a downlink subframe are allocated to the terminal apparatus. The assigning unit
A conversion unit that converts the quality of each channel acquired in the acquisition unit into an expected communication speed;
3. An execution unit that allocates at least two channels within a certain range of communication speeds to the terminal device based on the communication speeds of the respective channels converted by the conversion unit. The base station apparatus as described in. Obtaining the quality of each channel in a frame formed by a plurality of channels;
Assigning at least two channels whose quality is within a certain range to the terminal device based on the acquired quality;
Performing communication with the terminal device on at least two allocated channels;
A communication method comprising:

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