JP5185945B2 - Radio communication system and radio resource allocation method - Google Patents

Description

  The present invention relates to a radio communication system and a radio resource allocation method, and more particularly to orthogonal frequency division multiple access (OFDMA) and code division multiplexing for radio communication between a base station and a terminal apparatus. The present invention relates to a radio communication system, a base station, and a radio resource allocation method in which a plurality of types of radio access schemes are employed, such as access (CDMA: Code Division Multiple Access).

  As shown in FIG. 1, the mobile radio communication system includes a plurality of base station devices 10 (10-1 to 10-n) connected to a base station control device (BSC) 20 via a wired line, and each base station 10 includes It consists of a plurality of terminal devices (MS) 30 (30-1 to 30-m) which are located in the cells 11 (11-1 to 11-n) to be formed and communicate with the base station by radio. The base station controller 20 is connected to the public network NW via the mobile network switch 40.

  Each terminal device 30 is connected to the base station 10 by radio, and other terminals connected to the public network NW or other terminals connected to the base station 10 via the base station control device 20 and the mobile network switch 40 Communicate with the terminal device. In order for the terminal device 30 to communicate with the base station 10, a radio propagation environment in which the received power of the radio wave is equal to or higher than a certain value is required. If there is no shielding object between the terminal device and the base station, generally, a circular area 11 (11-1 to 11-n) centered on the base station 10 is a communication range (cell). Each terminal device 30 selects a base station with the best received power.

In a mobile communication network having a large number of terminals accommodated per base station, such as a cellular radio communication system, an array antenna composed of a plurality of directional antennas having different beam directions is employed as the antenna of each base station. In this case, each cell is logically divided into a plurality of sub-regions corresponding to the number of directional antennas. Such a sub-region logically divided is called a sector. In the following embodiments, radio resource allocation in units of cells will be described. However, the present invention can also be applied to radio resource allocation in units of sectors.
CDMA, which has been put into practical use since the 1990s, is known as a radio access method in a cellular radio communication system. In addition, research and development of OFDMA is progressing as a new access method for cellular radio suitable for high-speed communication.

  CDMA is a method of multiplexing a plurality of communication signals by applying a plurality of spreading codes with low correlation. In a CDMA communication system, a base station uses a same carrier frequency in the same time zone, Simultaneous communication with a terminal device is possible. Each terminal device 30 spreads the transmission signal with a spreading code unique to the terminal, and transmits it to the base station 10. The base station 10 separates the multiplexed spread spectrum signal by receiving the CDMA reception signal multiplexed in the radio section with a plurality of different despreading codes.

  Since CDMA can share time resources and frequency resources among a plurality of terminal devices, there is an advantage that the base station 10 can simultaneously communicate with a relatively large number of terminal devices. However, since CDMA cannot completely eliminate interference between spread spectrum signals, there is a demerit that communication quality deteriorates due to residual interference components.

  On the other hand, OFDMA, which is a type of frequency division multiple access (FDMA), multiplexes a plurality of communication signals by applying different time resources and frequency resources for each terminal. In OFDMA, a base station divides an available carrier band into a plurality of subcarriers at a constant frequency interval, and allocates a plurality of subcarriers corresponding to a requested band to each terminal apparatus. OFDMA differs from FDMA in that it enables high-speed processing by Fast Fourier Transform (FFT) by making the carrier interval constant.

  More specifically, the transmission side device generates a transmission signal in the assigned frequency domain (subcarrier group), and converts this to a signal in the time domain using an inverse fast Fourier transform (IFFT). And transmit as a radio signal. The receiving-side apparatus converts the received signal into a frequency domain signal by FFT, and reproduces the original transmission signal.

2A is a diagram conceptually showing multiple connections in an OFDMA communication system, and FIG. 2B shows the relationship between frequency resources (vertical axis) and time resources (horizontal axis).
In the OFDMA communication system, different frequency / time resources RS1, RS2, and RS3 are allocated to the plurality of terminal devices 30-1, 30-2, and 30-3. Here, as shown in FIG. 5B, the basic period T is divided into 8 time slots T1 to T8, and the first time slot is used as a time resource for the terminal devices 30-1, 30-2, and 30-3. T1 is allocated, and frequency blocks B1, B3, and B4 are respectively allocated as frequency resources. Each of the frequency blocks B1, B3, and B4 includes a predetermined number of subcarriers having different frequencies.

  In the base station 10, the transmission signal from the terminal device 30-1 can be extracted by selectively demodulating and decoding the reception signal of the frequency block B1 in the time slot T1. Similarly, transmission signals from the terminal devices 30-2 and 30-3 can be extracted by executing demodulation and decoding processing corresponding to the time / frequency resources RS2 and RS3.

  Here, different frequency resources in the first time slot are allocated to the terminal devices 30-1 to 30-3, but the remaining frequency resources (B2, B5 to Bn) of the first time slot, By allocating unused frequency resources in the second time slot to the eighth time slot to other terminal devices, the number of terminals communicating with the base station can be further increased.

  A terminal apparatus with transmission data transmits an allocation request for time / frequency resources (hereinafter referred to as OFDMA resources) for uplink data transmission to the base station, and the OFDMA resource specified by the resource allocation notification from the base station. Is used to transmit upstream data. In FIG. 2B, a frequency resource for one block is assigned to each terminal device for each basic period T. However, for a terminal device having a large amount of transmission data, a plurality of blocks in the same time slot are allocated. By assigning different carrier frequencies, it is possible to assign frequency sources in different bands for each terminal. Note that the terminal device that has failed to allocate resources retransmits the resource allocation request and waits for resource allocation.

  Thus, in OFDMA, each terminal apparatus can transmit data while occupying the time / frequency resources allocated from the base station, so that there is an advantage that data can be transmitted with good communication quality. However, OFDMA has a demerit that the number of communications that can be multiplexed simultaneously is small because a plurality of terminals cannot share the same frequency resource in the same time slot.

  In recent years, mobile radio systems that support both OFDMA and CDMA with different multiplexing methods have been studied. In 3GPP2 which is a standardization organization, as a main method of UMB (Ultra Mobile Broadband), for example, 3GPP2 C.P0084-0 v0.88 “Physical Layer for Ultra Mobile Broadband (UMB) Air Interface Specification” (Non-patent Document 1) , 3GPP2 C.P0084-0 v0.6 “Overview and Upper Layers for Ultra Mobile Broadband (UMB) Air Interface Specification” (Non-Patent Document 2) Has proposed a method of permitting simultaneous multiple connection by CDMA.

3A is a diagram schematically showing a mobile radio system that supports both OFDMA and CDMA proposed in Non-Patent Documents 1 and 2, and FIG. 3B is a frequency resource (vertical axis). And the relationship between time resources (horizontal axis).
Here, 30-1 to 30-3 are OFDM terminals, 30-4 and 30-5 are CDMA terminals, RS0 is a CDMA resource used by CDMA terminals 30-4 and 30-5, and RS1 to RS3 are OFDMA resources used by the OFDM terminals 30-1 to 30-3 are shown.

  The CDMA resource RS0 and the OFDMA resources RS1 to RS3 are secured so as not to overlap each other. The size of the frequency range used as the CDMA resource RS0 may be the same as or different from the frequency range used as the OFDMA resource. The CDMA resource RS0 (frequency range and time zone) is broadcast to each CDMA terminal in advance from the base station side.

  The terminal device 30 that transmits uplink data by OFDMA requests the base station 10 to allocate OFDMA resources each time data is transmitted, and transmits data using the time / frequency resources allocated by the base station. A terminal that transmits uplink data by CDMA can transmit data using a CDMA resource designated in advance without particularly making a resource allocation request to the base station.

  On the other hand, when the same terminal device can transmit data using a plurality of different communication methods, it is considered to optimize communication efficiency by dynamically selecting the best communication method for each data transmission. . For example, in IEICE Technical Report SR2006-42 (Non-patent Document 3), a control node is arranged above a plurality of wireless systems so that a terminal device can select and communicate with an optimal wireless system. The concept of a cognitive radio system has been proposed.

  Japanese Patent Laid-Open No. 2006-74492 (Patent Document 1) discloses a terminal in which a base station can receive data using both W-CDMA and OFDMA in a wireless communication system that supports two systems, W-CDMA and OFDMA. When a device (type A) and a terminal device (type B) capable of receiving data only by W-CDMA are mixed, the base station feeds back the W-CDMA / OFDMA resource usage rate and each terminal. Based on the channel quality information (including terminal type A and B identification information), it has been proposed to select whether W-CDMA or OFDMA is used to transmit downlink data addressed to a type A terminal. . At this time, the type A terminal waits for downlink data in both W-CDMA and OFDMA so that the base station can receive downlink data regardless of whether the base station selects W-CDMA or OFDMA.

JP 2006-74492 A 3GPP2 C.P0084-0 v0.88 Physical Layer for Ultra Mobile Broadband (UMB) Air Interface Specification 3GPP2 C.P0084-0 v0.6 Overview and Upper Layers for Ultra Mobile Broadband (UMB) Air Interface Specification IEICE Technical Report SR2006-42

  In Patent Document 1, in an environment where a terminal capable of receiving data by both W-CDMA and OFDMA (type A) and a W-CDMA terminal (type B) coexist, the type is set so as not to run out of W-CDMA resources. It has been proposed to improve the communication efficiency of downlink data from the base station to the terminal device by preferentially assigning OFDMA resources to the terminal A. Further, in Patent Document 1, the base station feeds back line information indicating line quality information and type (A, B) identification information of the transmission source terminal to each terminal apparatus, and based on the terminal apparatus type indicated by the line information. In addition, the downlink terminal described above in consideration of the ratio of the resource usage rate of W-CDMA and OFDMA or the ratio of the number of type A terminals to the number of type B terminals as known by the base station It is proposed to allocate resources for each.

  An object of the present invention is to provide a wireless environment in which a first type terminal apparatus capable of transmitting uplink data by OFDMA and a second type terminal apparatus capable of transmitting uplink data by either OFDMA or CDMA coexist. In this case, the allocation of uplink resources to each terminal apparatus is realized by effectively using OFDMA resources and CDMA resources.

  The resource allocation principle of Patent Document 1 is that when a type A terminal and a type B terminal coexist, a resource (W-CDMA resource) common to both types is left for the type B terminal. The terminal is preferentially assigned non-common resources (OFDMA resources). Therefore, when the resource allocation principle shown in Patent Document 1 is applied to the wireless communication system targeted by the present invention, a CDMA resource that is a non-common resource is preferentially allocated to the second type terminal device, and as a result In addition, there is a problem that the second type terminal apparatus cannot receive the merit of OFDMA.

  Also, in the uplink communication from the terminal device to the base station, the radio wave propagation environment is different for each terminal, so if all the terminals transmit signals with the same power, the signal reception quality at the base station is different for each terminal. It will be different. For this reason, in the mobile radio communication system, transmission power control for optimizing transmission power is performed for each terminal device so that reception signals from all terminals have a predetermined quality on the base station side.

  Therefore, in response to an uplink resource allocation request issued from the second type terminal device, as in Patent Document 1, the terminal type (first and second types) is independent of the radio wave propagation environment of the request source terminal. If the resource allocation based on only is performed, the second type terminal apparatus having a poor radio wave propagation environment is forced to transmit data by CDMA. In this case, there is a possibility that communication quality deteriorates and QoS (Quality of Service) required by the terminal cannot be satisfied.

  Another object of the present invention is a radio in which the first type terminal device and the second type terminal device described above coexist, and the base station manages uplink radio communication resources by dividing them into OFDMA resources and CDMA resources. Provided is an uplink resource allocation method capable of increasing OFDMA resource allocation opportunities not only for first type terminal devices but also for second type terminal devices by effectively using radio communication resources in a communication system There is to do.

  In order to achieve the above object, the present invention is capable of transmitting uplink data by OFDMA, transmitting a control signal by CDMA, and transmitting uplink data by either OFDMA or CDMA, and transmitting a control signal by CDMA. In the wireless communication system in which the second type terminal device transmitting in the coexistence, the base station manages the uplink wireless communication resource by dividing it into OFDMA resources and CDMA resources, and the OFDMA resources and the OFDMA resources according to the usage rate of the OFDMA resources The resource allocation to the resource allocation requesting terminal device is executed while dynamically changing the ratio with the CDMA resource.

  More specifically, in the radio communication system of the present invention, the base station manages the uplink radio communication resources by dividing them into OFDMA resources and CDMA resources, and performs resource allocation in response to a resource allocation request from each terminal apparatus. A control unit, and the OFDM control unit includes resource optimization means for dynamically changing a ratio of the OFDMA resource and the CDMA resource constituting the uplink radio communication resource according to a use rate of the OFDMA resource. It is characterized by that.

  The OFDM control unit, for example, defines uplink radio communication resources in a plurality of time / frequency regions, and stores them separately in a time / frequency region serving as an OFDMA resource and a time / frequency region serving as a CDMA resource. A resource management table that manages the usage state of the OFDMA resource and changes the ratio of the OFDMA resource to the CDMA resource described above.

  In one embodiment of the present invention, the resource optimization unit increases the CDMA resource to decrease the OFDMA resource when the OFDMA resource usage rate is equal to or lower than the first threshold, and the OFDMA resource usage rate is: When the second threshold value larger than the first threshold value is exceeded, the CDMA resource is decreased and the OFDMA resource is increased. However, an upper limit is set for the OFDMA resource, and a predetermined amount of resource is always secured for CDMA.

  Another feature of the present invention is that the OFDM controller executes resource allocation for each reference period for the terminal device that has issued the resource allocation request, and there is a shortage of free OFDMA resources relative to the total amount of requested resources. Sometimes, priority is given to the allocation of OFDMA resources to the first type terminal apparatus, and the allocation of OFDMA resources to the second type terminal apparatus is suppressed. When the allocation of the OFDMA resource fails, the second type terminal apparatus transmits uplink data by CDMA or retransmits the resource allocation request and waits for the OFDMA resource to be allocated.

  In one embodiment of the present invention, when the OFDM control unit runs out of free OFDMA resources with respect to the total amount of requested resources, the transmission power is reduced between the first type terminal device and the second type terminal device. OFDMA resource allocation scheduling is executed for terminals that are equal to or greater than a predetermined threshold.

  In another embodiment of the present invention, when the OFDM control unit runs out of free OFDMA resources with respect to the total amount of requested resources, the first type terminal apparatus is assigned a reference weighting factor, and the second type terminal A weighting factor corresponding to the transmission power is given to the apparatus, and OFDMA resource allocation scheduling is executed according to the priority weighted by the weighting factor. However, for the second type terminal device, for example, a weighting factor corresponding to the transmission power and the average transmission data rate or a weighting factor corresponding to the transmission power and the requested QoS may be given. .

  According to the radio resource allocation method of the present invention, a step of broadcasting a CDMA resource for transmitting uplink data from a base station to each terminal device, and a resource allocation request from any of the terminal devices to the base station And the base station calculates the total amount of requested resources for each reference period, and when there is a shortage of empty OFDMA resources, priority is given to the allocation of OFDMA resources to the first type terminal apparatus, and A step of transmitting an allocation scheduling and transmitting a notification message indicating a resource allocation result to the terminal device that has issued the resource allocation request, and a terminal device that has successfully allocated the OFDMA resource are notified by the notification message. Transmitting uplink data to the base station using a specified OFDMA resource If the terminal device that failed to allocate OFDMA resources is the second type, determine whether to transmit the transmission data by CDMA or retransmit the resource allocation request to the base station, and execute an operation corresponding to the determination result Step.

  The radio resource allocation method according to the present invention further includes a step in which the base station dynamically changes the ratio of the OFDMA resource and the CDMA resource constituting the uplink radio communication resource according to the usage rate of the OFDMA resource. including.

  According to the present invention, since the ratio of the OFDMA resource and the CDMA resource constituting the uplink radio communication resource is dynamically changed according to the usage rate of the OFDMA resource, the number of resource allocation requesting terminals increases. Then, when the utilization rate of the OFDMA resource exceeds a predetermined threshold, a part of the CDMA resource is changed to the OFDMA resource, and resource allocation is executed in a state where the OFDMA resource is maximized, whereby the first type terminal device In addition, OFDMA resources with good communication characteristics can be assigned to the second type terminal apparatus.

  In addition, when there is a shortage of free OFDMA resources with respect to the total amount of requested resources, priority is given to the allocation of OFDMA resources to the first type terminal device. For the second type terminal device, for example, a terminal having a poor propagation environment Can be selectively allocated OFDMA resources. In this case, if the uplink data can be CDMA transmitted to another terminal device of the second type that could not secure the OFDMA resource, the wireless communication resource was effectively used by transmitting the data using the CDMA resource. Uplink data transmission can be realized, and QoS guarantee of a real-time service such as VoIP (Voice over IP) becomes easy.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 4 is a block configuration diagram showing an embodiment of the terminal device 30 to which the present invention is applied.
The terminal 30 includes a radio transmission / reception circuit 310 connected to the antenna 311, an OFDM transmission circuit 320 and an OFDM reception circuit 330 connected to the radio transmission / reception circuit 310, and an OFDM connected to these OFDM transmission / reception circuits 320 and 330. It comprises a control unit 300 and a protocol processing unit 31, a processor 32 connected to a bus 39, a memory 33, an audio CODEC 34, a display unit 35 and an input unit 36, and a speaker 37 and a microphone 38 connected to the CODEC 34. In the memory 33, various control routines and application programs executed by the processor 32 are prepared.

  The terminal user uses the input operation buttons prepared in the input unit 36 and the display unit 35 to perform operations such as switching of a display screen, selection of a telephone number and a destination address, data input, and data transmission / reception. The voice input from the microphone 38 is converted into encoded voice data by the CODEC 34. The encoded audio data output from the CODEC 34 and the transmission data read from the memory 33 are converted into transmission packets by the protocol processing unit 31 and input to the OFDM transmission circuit 320.

  The OFDM transmission circuit 320 converts the transmission packet into a subpacket and outputs it to the wireless transmission / reception circuit 310. The radio transmission / reception circuit 310 converts the transmission subpacket into a signal in the radio section, amplifies the power, and transmits the signal from the antenna 311 to the base station 10. A received signal from the base station 10 received by the antenna 311 is converted into a baseband symbol by the wireless transmission / reception circuit 310 and then input to the OFDM reception circuit 330.

  The OFDM receiving circuit 330 performs a decoding process on received data. The reception data decoded by the OFDM reception circuit 330 is output to the reception buffer on the CODEC 34 or the memory 33 via the protocol processing unit 31. The CODEC 34 converts the received encoded audio signal into an analog audio signal and outputs the analog audio signal to the speaker 38. The reception data stored in the reception buffer is processed by the processor 32 and transferred to a specific file area on the memory 33 or the display unit 35 according to the application.

FIG. 5 shows details of the OFDM control unit 300, the OFDM transmission circuit 320, and the OFDM reception circuit 330.
The OFDM transmission circuit 320 includes, for example, an encoder 321 that turbo-codes transmission data and generates a transmission packet with redundant bits, a transmission packet output from the encoder 321, and a control channel output from the OFDM control unit 300. A modulator 322 that modulates a signal, a subcarrier mapping unit 323 that maps modulation symbol sequences output from the modulator 322 to predetermined subcarriers of OFDM, and an inverse connected to the subcarrier mapping unit 323 To the data symbols output from the discrete Fourier transform (IDFT) unit 324 and the IDFT unit 324, for example, a synchronization symbol required by the receiving circuit of the base station, such as CP (Continuous Pilot), and other control symbols are added, Control symbol adding section 325 for outputting to radio transmission / reception circuit 310 And a CDMA multiplexing unit 326.
The CDMA multiplexing unit 326 multiplexes a plurality of types of signals transmitted by the OFDM control unit 300 through the CDMA channel. The output of the CDMA multiplexing unit 326 is input to the IDFT unit 324 together with the output of the subcarrier mapping unit 323.

  On the other hand, the OFDM receiver circuit 330 receives a plurality of predetermined subcarriers from a discrete Fourier transform (DFT) unit 331 that performs Fourier transform on the received baseband symbol input from the radio transceiver circuit 310 and an output of the DFT unit 331. From the subcarrier demapping unit 332 that extracts the upper signal sequence, the demodulator 333 that demodulates the signal sequence of the data channel, control channel, and pilot channel output from the subcarrier demapping unit 332, and the demodulator 333 And a decoder 334 for decoding received data output as a demodulated symbol string of the data channel.

  OFDM control section 300 receives a plurality of demodulated symbol sequences of control channels and pilot channels output in parallel from demodulator 333. The OFDM control unit 300 detects a resource allocation message transmitted by the base station 10 from a demodulation symbol string of F-SCCH that is one of the control channels, and also uses a demodulation symbol string of F-ACKCH that is one of the control channels. Then, ACK / NAK transmitted by the base station 10 is extracted, and transmission and retransmission of uplink data are controlled. In addition, the OFDM control unit 300 generates a resource allocation request to be transmitted to the base station 10 and other information in response to a data transmission request from the protocol processing unit 31, and the modulator 323 and / or the CDMA multiplexing unit To 326.

  In this embodiment, the terminal device 30 includes a first type that uses the CDMA multiplexing unit 326 only for transmission of control channel signals (hereinafter referred to as “OFDMA terminal”), and an CDMA multiplexing unit 326 that is connected to the terminal device 30. There is a second type (hereinafter referred to as “OFDMA / CDMA terminal”) that can be used for both control channel signal transmission and uplink data channel (traffic channel) signal transmission.

  The OFDM control unit 300 of the OFDMA terminal uses the OFDMA resource specified by the base station only when the OFDMA resource is allocated from the base station 10 in response to the uplink OFDMA resource allocation request, and uses the OFDMA resource specified by the base station to transmit the upper data in OFDMA. Send. In this case, the transmission data is input to the subcarrier mapping unit 323 via the encoder 321 and the modulator 322, and the frequency resource (subcarrier group) specified by the base station with the time resource (time slot) specified by the base station. ).

  On the other hand, the OFDM control unit 300 of the OFDMA / CDMA terminal uses the OFDMA resource specified by the base station in the same way as the OFDMA terminal when the OFDMA resource is allocated from the base station 10 in response to the uplink resource allocation request. Then, the upper data is transmitted by OFDMA. If there is no allocation of OFDMA resources, the OFDM control unit 300 of the OFDMA / CDMA terminal determines whether or not transmission-waiting data can be transmitted by CDMA, and if transmission is possible, transmits data by CDMA and cannot perform CDMA transmission. For example, it retransmits the uplink resource allocation request and waits for OFDMA resource allocation. When transmitting data by CDMA, OFDM control section 300 inputs the output of encoder 321 to CDM multiplexing section 326.

FIG. 6 shows an embodiment of the OFDM control unit 100, the OFDM transmission circuit 120, and the OFDM reception circuit 130 that constitute the radio transmission / reception unit of the base station 10.
The OFDM transmission circuit 120 turbo-codes transmission data to generate a transmission packet with redundant bits, the transmission packet (data channel signal) output from the encoder 121, and the OFDM control unit 100 Modulator 122 that modulates control channel and pilot channel signals, subcarrier mapping unit 123 that maps modulation symbol sequences of a plurality of channels output from modulator 122 to predetermined OFDM subcarriers, and subcarrier mapping unit 123, an inverse discrete Fourier transform (IDFT) unit 124, a data symbol output from the IDFT unit 124, a synchronization symbol necessary for a receiving circuit of a terminal such as a CP (Continuous Pilot), and other control The radio transmission / reception circuit 110 is added with the symbol And a control symbol adding unit 125 that outputs to

  On the other hand, the OFDM receiver circuit 130 includes a discrete Fourier transform (DFT) unit 131 that performs a Fourier transform on the received baseband symbol input from the radio transceiver circuit 110, and a plurality of pre-specified subcarriers from the output of the DFT unit 131. The subcarrier demapping unit 132 that extracts the upper signal sequence, the demodulator 133 that demodulates the signal sequence of the data channel and control channel output from the subcarrier demapping unit 132, and the data channel from the demodulator 133 It comprises a decoder 134 that decodes received data output as a demodulated symbol string, and a CDMA receiver 135 connected to the DFT unit 131. The CDMA receiving unit 137 demodulates the control channel signal sequence transmitted by each terminal by CDMA and the traffic data transmitted by the OFDMA / CDMA terminal by CDMA, and inputs the demodulated data to the OFDM control unit 100.

  The OFDM control unit 100 generates a pilot signal to be transmitted to the terminal and various control channel information, and outputs the pilot signal to the modulator 123. The OFDM control unit 100 receives the control channel reception signal sequence output in parallel from the demodulator 133 and the control channel and traffic channel reception signal sequences demodulated by the CDMA reception unit 137. The traffic data transmitted by the CDMA terminal by CDMA is transferred to the demodulator 134 via the OFDM control unit 100.

  The OFDM control unit 100 includes a memory that stores a terminal (MS) management table 140, a resource management table 141, and a resource allocation request management table 142, and a memory (not shown) that stores various programs. In response to the resource allocation request received from, a resource allocation process for uplink data transmission is executed, and a resource allocation message indicating the allocation result is transmitted to the requesting terminal at a predetermined timing. The resource allocation process is periodically executed with reference to the management tables 140 to 142.

FIG. 7 shows an example of the terminal (MS) management table 140.
The MS management table 140 includes a plurality of table entries having a terminal MAC identifier (MS-MAC ID) 1401, and each table entry includes a terminal ID (MS-ID) 1402, a CDMA traffic capability 1403, and a CDMA use. A spreading code (code identifier) 1404, a PAH (Power Amplifier Headroom) 1405 indicating uplink transmission power, and other information are shown. The CDMA traffic capability 1403 indicates whether or not the terminal specified by the terminal MAC identifier 1401 can transmit uplink data even by CDMA. The OFDM control unit 100 refers to the CDMA traffic capability 1403 so that the terminal can receive the OFDMA. It is possible to determine whether the terminal is an OFDMA / CDMA terminal. PAH 1405 indicates the ratio of the current pilot transmission power to the maximum transmission power of the terminal. If the PAH value is large, it means that the terminal can communicate with the base station with a small transmission power.

FIG. 8 shows an example of the resource management table 141.
The resource management table 141 uses frequency resources (frequency blocks B1 to Bn) on the vertical axis and time resources (time slots T1 to T8) within the basic period T on the horizontal axis, and is used for uplink communication from the terminal to the base station. The allocation status of frequency resources and time resources to be performed is shown.

  In the illustrated example, the base station 10 divides the frequency band into a plurality of frequency blocks B1 to Bn, divides the basic period T into 8 time slots T1 to T8, and then includes a plurality of time slots T5 and T8 in the time slot T8. Frequency blocks are assigned for CDMA control, a plurality of frequency blocks in time slots T1 to T3 are assigned for CDMA traffic, and other resources are assigned for OFDMA. A resource in which MS-ID (MS1, MS2,...) Is entered means a resource allocated to the terminal, and a resource in which a symbol “-” is entered means that the resource is currently free. ing.

FIG. 9 shows an example of the resource allocation request management table 142.
The resource allocation request management table 142 includes a plurality of table entries having the MAC identifier (MS-MAC ID) 1421 of the request source terminal. Each table entry includes, for example, a transmission buffer level (number of requested frequency blocks) 1422 indicating the amount of transmission waiting data in the request source terminal, a QoS class 1423 and a delay limit 1424 required by the request source terminal, and the request source terminal A transmission power level (PAH) 1425, an allocated resource type 1426, and other information 1427 are shown. Other information includes, for example, an average data rate at the request source terminal.

  When receiving the first uplink resource allocation request message from the terminal, the base station 10 generates a new table entry having the MS-MAC ID of the request source terminal, and adds this to the resource allocation request management table 142. In parameters 1422-1424, the value extracted from the received message is recorded when the resource allocation request message is received, and the value read from MS management table 140 is recorded in transmission power (PAH) 1425.

  The allocation resource type 1426 stores the resource type (OFDMA or CDMA) allocated to each terminal during the resource allocation process. When transmission data is generated, each terminal 30 requests the base station 10 to allocate an OFDMA resource, and performs data transmission using the resource (specified frequency block of a specified time slot) allocated from the base station. . When data transmission cannot be completed within the basic period T, each terminal 30 repeats data transmission with the same allocated resource over a plurality of periods.

  In the following embodiment, the OFDM control unit 100 of the base station deletes the table entry corresponding to the released terminal from the resource allocation request management table 142 when the connection with the terminal is released. When each terminal completes transmission of uplink data using the allocated resource, it waits for the generation of the next transmission data, and transmits a resource allocation request to the base station 10 each time new transmission data is generated.

  When the OFDM control unit 100 receives a new resource allocation request from a terminal whose terminal identifier (MS-MAC ID) has already been registered in the resource allocation request management table 142, the OFDM control unit 100 uses the allocated resource in the table entry corresponding to the request source terminal. The type 1426 is cleared, the values of the transmission buffer level 1422, the QoS class 1423, and the delay limit 1424 are updated according to the parameter values indicated by the received resource allocation request, and the PAH 1425 is rewritten. The OFDM control unit 100 repeats resource allocation scheduling for each basic period T for a table entry in which the allocation resource type 1426 is in a clear state.

  Next, an embodiment of the resource allocation method executed by the base station 10 will be described.

  In the first embodiment, when the resource amount for OFDMA is insufficient, the base station 10 (OFDM control unit 100) has a large transmission power among OFDMA terminals or OFDMA / CDMA terminals that cannot transmit uplink data by CDMA. OFDMA resources are preferentially assigned to terminals. Further, the base station increases / decreases the CDMA resource according to the usage rate of the OFDMA resource determined from the resource allocation request management table 142, and optimizes the ratio of the OFDMA resource to the CDMA resource.

  If each terminal succeeds in assigning OFDMA resources, each terminal transmits uplink data using the assigned OFDMA resources. When the allocation of the OFDMA resource fails, the OFDMA terminal repeats the transmission of the resource allocation request until the OFDMA resource allocation is successful. On the other hand, if the transmission data may be transmitted by CDMA, the OFDMA / CDMA terminal transmits data by CDMA. If the transmission data is not suitable for CDMA transmission, the OFDMA / CDMA terminal does not execute resource allocation until the allocation of OFDMA resources is successful. Repeat sending the allocation request.

FIG. 10 shows an example of a communication sequence executed between the terminal device 30 and the base station 10.
Before starting the data communication, the terminal 30 negotiates with the base station 10 regarding switching of the communication mode (SQ01). The base station 30 notifies the terminal 30 of CDMA resources that can be used for uplink traffic on the downlink control channel, and the terminal 30 registers the availability of CDMA uplink data transmission (CDMA traffic capability) in the base station 10. .

The negotiation SQ01 is executed, for example, when the terminal 30 issues a call connection request or when the terminal 30 is handed off from the adjacent cell to the base station 10. However, the negotiation SQ01 may be executed when the terminal 30 starts communication of a data type that can be transmitted by either OFDMA or CDMA.
In the process of the negotiation SQ01, the base station 10 acquires information such as the MS-MAC ID, MS-ID, CDMA traffic capability, and spreading code of the terminal 30 and stores it in the MS management table 140.

  When the negotiation SQ01 ends, the terminal 30 periodically notifies the base station 10 of the current uplink transmission power state (PAH) (SQ02). The base station 10 stores the PAH notified from each terminal 30 in the MS management table 140 (SQ03) and periodically assigns CDMA resources (carrier frequency and time slot) that can be used for uplink data transmission to each terminal. (SQ04).

  When the transmission data is generated, the terminal 30 transmits an uplink OFDMA resource allocation request message to the base station 10 (SQ05). The resource allocation request message includes parameter information such as a transmission buffer level (or the number of requested frequency blocks) indicating the amount of transmission data in the terminal 30, a QoS class desired by the terminal, and a delay limit.

  Upon receiving the OFDMA resource allocation request message, the base station 10 adds a new table entry having the MS-MAC ID indicated by the OFDMA resource allocation request message to the resource allocation request management table 142 (SQ06). For each period T, an uplink resource allocation process (SQ07) is executed, and the resource allocation result is notified to the request source terminal 30 (SQ08). If the table entry corresponding to the MS-MAC ID of the request source terminal already exists, the base station 10 executes the uplink resource allocation process (SQ07) after updating the contents of the table entry as described above.

  In the uplink resource allocation process (SQ07), resource allocation is executed for a terminal in which the allocation resource type 1426 is in a clear state. As will be described in detail with reference to FIG. 11, in the uplink resource allocation processing, whether or not the OFDMA resource can be allocated to the requesting terminal is determined based on the usage rate of the OFDMA resource, the CDMA traffic capability of the requesting terminal 30 and the transmission power state. Is done.

  Upon receipt of the resource allocation notification, the terminal 30 executes a used resource determination process (SQ09) described in detail in FIG. 12, and when there is an OFDMA resource allocation, transmits uplink data using the allocated OFDM resource. (SQ10). When there is no OFDMA resource allocation, the terminal 30 determines whether or not data transmission by CDMA is possible, and makes a re-request for CDMA data transmission or OFDMA resource allocation.

  When the base station 10 allocates OFDMA resources to the terminal 30, the base station 10 receives transmission data in the time slot and frequency block designated by the resource allocation notification, and transmits retransmission control information indicating the data reception result to the terminal 30 (SQ11 ). If the OFDMA resource cannot be allocated to the terminal 30, the base station cannot accurately determine whether the terminal 30 transmits data by CDMA and in which time slot. Therefore, the base station 10 waits for reception of uplink CDMA transmission data from a plurality of terminals indicated by the MS management table 140 using the frequency block and time slot for uplink CDMA traffic indicated by the resource management table 141, and displays the data reception result. The retransmission control information shown is transmitted to the terminal 30 (SQ11).

  In parallel with the uplink resource allocation process (SQ07) described above, the base station 10 periodically executes the CDMA resource optimization process (SQ12) based on the resource management table. The CDMA resource optimization process will be described later in detail with reference to FIG.

FIG. 11 shows a flowchart of an uplink resource allocation processing routine 500 executed by the OFDM control unit 100 of the base station 10 every basic period T in this embodiment.
In the uplink resource allocation processing routine 500, the OFDM control unit 100 searches the resource allocation request management table 142 for a table entry in which the allocated resource type 1426 is cleared, and sets the MS-MAC ID as the resource allocation target terminal. (Step 501). The OFDM control unit 100 sets the number of resource allocation target terminals in the parameter N, the initial value “0” in the count parameter i (502), and the requested frequency block number (transmission buffer level) indicated by the table entry of the resource allocation target terminal A total amount R of allocation request resources is calculated from 1422 (503).

  Next, the OFDM control unit 100 refers to the resource management table 141 to check the state of the CDMA resource for uplink traffic (504), and if there is no CDMA resource allocated for uplink traffic, All the terminals are selected as OFDMA resource allocation candidates (512), and an OFDMA resource allocation process (520) is executed.

  When there is a CDMA resource for uplink traffic, the OFDM control unit 100 refers to the resource management table 141 and determines whether or not the OFDMA resource in an empty state can satisfy the total amount R of allocation request resources ( 505). When the free OFDMA resource can satisfy the total amount R of allocation request resources, the OFDM control unit 100 selects all the terminals that are the resource allocation targets as OFDMA resource allocation candidates (512), and allocates OFDMA resources. The process (520) is executed.

  If the free OFDMA resource cannot satisfy the total allocation request resource amount R, the OFDM control unit 100 increments the value of the parameter i (506) and sets the MS-MAC ID of the i-th terminal that is the resource allocation target as a key. Then, the CDMA traffic capability 1403 is searched from the MS management table 140, and it is determined whether or not the i-th terminal can transmit uplink data by CDMA (507).

  When the i-th terminal cannot transmit uplink data by CDMA, the OFDM control unit 100 selects the i-th terminal as an OFDMA resource allocation candidate (509), and compares parameters i and N (511). When the i-th terminal can transmit uplink data by CDMA, the OFDM control unit 100 compares the transmission power (PAH) 1105 of the i-th terminal with the threshold THp (508), and the transmission power <THp (PAH ≧ THp) Selects the i-th terminal as a CDMA resource allocation candidate (510), otherwise selects the i-th terminal as an OFDMA resource allocation candidate (509) and compares parameters i and N (511) . While the parameter is i <N, the OFDM control unit 100 repeats the operations in and after step 506, and when i = N, executes OFDMA resource allocation processing (520).

  In the OFDMA resource allocation process (520), for example, the ratio R between the number of requested frequency blocks of each terminal selected as an OFDMA resource allocation candidate and the average number of requested frequency blocks (average transmission rate) of all candidate terminals. Then, OFDMA resource allocation is scheduled in order from candidate terminals having a larger ratio R value. An OFDMA resource allocation candidate terminal is assigned an OFDMA resource that is free on the resource management table 141 in accordance with the number of requested frequency blocks, and notifies the OFDMA resource to be used in a resource allocation notification message. The OFDMA display is stored in the allocation resource type 1426 of the allocation request management table 142. A resource allocation notification message indicating that the OFDMA resource has not been allocated is transmitted to a terminal that is a candidate for CDMA resource allocation, and the CDMA indication is stored in the allocated resource type 1426 of the resource allocation request management table 142.

FIG. 12 shows a flowchart of a used resource determination processing routine 600 executed by each terminal 30 (OFDM controller 300) when a resource allocation notification message is received from the base station 10.
In the used resource determination processing routine 600, the OFDM control unit 300 determines whether or not an OFDMA resource is allocated from the received message (601). If the OFDMA resource is allocated, uplink data is transmitted using the specified OFDMA resource. Send. When the allocation of the OFDMA resource fails, the OFDM control unit 300 determines whether the terminal itself is an OFDMA / CDMA terminal capable of CDMA transmission of uplink data (602). In response, the resource allocation request is retransmitted (613).

  When the own terminal is an OFDMA / CDMA terminal, the OFDM control unit 300 determines whether or not transmission-waiting data can be transmitted by CDMA (603), and if it is data that can be transmitted by CDMA, it is already notified by CDMA resource notification. Uplink data is transmitted using the already completed CDMA resource (612). If the transmission waiting data is inappropriate for CDMA transmission, the OFDM control unit 300 retransmits the resource allocation request to the base station (613).

  If the OFDMA / CDMA terminal does not allocate the OFDMA resource even if the resource allocation request is retransmitted, the OFDMA / CDMA terminal may forcibly switch from OFDMA data transmission to CDMA data transmission in decision step 603. . In addition, when the number of retransmissions of the OFDMA resource allocation request or the data waiting time in the transmission queue exceeds a predetermined threshold, a determination is made as to whether transmission-waiting data is transmitted by CDMA or retransmission of the uplink OFDM resource request is stopped. You may make it perform.

FIG. 13 shows a flowchart of a CDMA resource optimization processing routine 530 periodically executed by the OFDM control unit 100 of the base station.
In the CDMA resource optimization processing routine 530, the OFDM control unit 100 calculates the usage rate U of the uplink OFDMA resource in the resource management table 141 (531). The usage rate U is calculated from an empty OFDMA resource (number of frequency blocks) indicated by the resource management table 141 and an already assigned OFDMA resource (number of frequency blocks).

  Next, the OFDM control unit 100 compares the current OFDMA resource usage rate U with the first threshold TH1 (532), and when the usage rate U is equal to or lower than TH1, determines whether or not the CDMA resource can be increased (533). For example, the ratio of the OFDMA resource and the CDMA resource in the resource management table 141 is compared with a threshold value. If the occupation rate of the CDMA resource is smaller than the threshold value, it is determined that the CDMA resource can be increased.

  If the CDMA resource cannot be increased, the OFDM control unit 100 terminates this routine. If the CDMA resource can be increased, the OFDM control unit 100 stores a predetermined fixed amount (or a fixed rate) in the resource management table 141 that is currently free. The OFDMA resource (frequency block) is changed for CDMA traffic (534), and this routine is terminated.

  When the OFDMA resource usage rate U exceeds the first threshold value TH1, the OFDM control unit 100 compares the usage rate U with the second threshold value TH2 (where TH2> TH1) (535), and the usage rate U is less than TH2. If so, this routine ends. When U> TH2, the OFDM control unit 100 determines whether or not the CDMA resource can be reduced (526). If the reduction is possible, a predetermined amount of resources (frequency blocks) for CDMA traffic are stored in the resource management table 141. The routine is terminated after changing to OFDMA (537).

  Whether or not the CDMA resource can be reduced is determined by, for example, counting the number of terminals M in which the allocation resource type 1426 is CDMA in the resource allocation management table 142 and the resource amount (number of blocks) used for CDMA traffic in the resource management table 141 And the ratio of the number M of CDMA assigned terminals can be determined by comparing with a predetermined threshold.

  By periodically executing the CDMA resource optimization processing routine 530, while the OFDMA resource usage rate U is between the thresholds TH1 and TH2, the current allocation of the OFDMA resource and the CDMA resource is maintained, and the OFDMA resource When the usage rate exceeds TH2, the CDMA resource is reduced (OFDM resource is increased), and when the usage rate of the OFDMA resource is lower than TH1, the CDMA resource is increased (OFDMA resource is reduced), and the CDMA resource and the OFDMA Resources can be optimized.

  According to the first embodiment, when uplink OFDMA resources are insufficient, out of OFDMA / CDMA terminals capable of transmitting uplink data even by CDMA, terminals having a good radio wave propagation environment are excluded from OFDMA resource allocation targets, and data is transmitted by CDMA. By transmitting, the base station can effectively allocate OFDMA resources to a plurality of terminals. Further, by changing the ratio of the CDMA resource and the OFDMA resource according to the utilization rate of the OFDMA resource, the base station can dynamically cope with the resource demand from the terminal.

Next, a second embodiment of the present invention will be described.
In the first embodiment, when the OFDMA resource is insufficient, the base station 10 transmits a transmission among a general OFDMA terminal that cannot transmit uplink data by CDMA and an OFDMA / CDMA terminal that can transmit uplink data by CDMA. An OFDMA resource allocation process is executed for resources whose terminals have a power of a predetermined threshold or more.

  In the second embodiment, when the OFDMA resources are insufficient, all of the OFDM terminals and OFDMA / CDMA terminals are targeted for resource allocation, and for the OFDMA / CDMA terminals, the scheduling priority is weighted according to the transmission power, An OFDMA resource allocation process is executed in order of priority. For example, a weight coefficient “1” is applied to a general OFDMA terminal that cannot transmit uplink data by CDMA, and a weight coefficient that changes according to transmission power is applied to an OFDMA / CDMA terminal. Modify the scheduling priority of each terminal.

  Among OFDMA / CDMA terminals, the weighting of the priority is such that the scheduling priority of a terminal having a poor radio wave propagation environment and a large transmission power is increased, and the scheduling priority of a terminal having a good radio wave propagation environment and a low transmission power is decreased. By performing the processing, when the OFDMA resources are insufficient, the OFDMA resources can be allocated to OFDMA / CDMA terminals having a poor radio wave propagation environment in addition to the OFDMA terminals.

FIG. 14 shows a flowchart of an uplink resource allocation processing routine 500 of the second embodiment executed by the OFDM control unit 100 of the base station. The processing contents of steps 501 to 507 and 511 are the same as those in the first embodiment described with reference to FIG.
In the second embodiment, when the free OFDMA resource satisfies the allocation request resource total amount R, the OFDM control unit 100 assigns a reference weight coefficient to all the terminals (531), and assigns the OFDMA resource ( 521) is executed, and when there is a shortage of free OFDMA resources, it is determined whether or not the i-th terminal that is the resource request source can transmit data by CDMA (507).

  When the i-th terminal is an OFDMA / CDMA terminal capable of transmitting data by CDMA, the OFDM control unit 100 assigns a weighting factor corresponding to the transmission power to the i-th terminal (532), executes step 511, and executes the i-th terminal. If the terminal is a general OFDMA terminal that cannot transmit data by CDMA, a reference weight coefficient is assigned to the i-th terminal (533), and step 511 is executed.

  When the scheduling priority of resource allocation of an OFDMA / CDMA terminal is multiplied by a weight coefficient smaller than the reference value “1”, the priority is lowered than that of the OFDMA terminal, and when the weighting coefficient smaller than “1” is multiplied, the priority is increased. be able to. For example, in step 532, the transmission power of the terminal is larger than “1” for an OFDMA / CDMA terminal whose transmission power is equal to or greater than a certain threshold. In OFDMA resource allocation (521), by assigning a weighting factor and assigning a weighting factor of “1” or less proportional to the transmission power to OFDMA / CDMA terminals whose transmission power is smaller than the above threshold, For OFDMA / CDMA terminals, it is possible to execute allocation scheduling with weighted priorities.

  In the OFDMA resource allocation (520) of the first embodiment, the ratio R between the number of requested frequency blocks and the average number of requested frequency blocks is adopted as a parameter indicating the scheduling priority. The OFDMA resource allocation is executed in order from the terminal having the largest value. In the OFDMA resource allocation (521) of the second embodiment, the OFDM control unit 100 sets the scheduling priority (ratio R) value of each terminal to the step. After weighting according to the weighting factor given in 531, 532 or 533, OFDMA resource allocation is executed in order of priority.

As in the first embodiment, the OFDMA / CDMA terminal 30 that has transmitted the uplink resource allocation request transmits uplink data by OFDMA when there is an OFDMA resource allocation from the base station 10, and there is no OFDMA resource allocation. If it is determined that the uplink data is transmitted by CDMA, the resource allocation request is retransmitted.
According to the present embodiment, it is possible to maximize the utilization rate of OFDMA resources and allocate OFDMA resources giving priority to OFDMA terminals that cannot transmit data by CDMA and OFDMA / CDMA terminals that have poor radio wave propagation environments.

For the weighting of the scheduling priority in the second embodiment, a weighting factor determined by a combination of the transmission power and other parameters described above may be applied.
As another parameter, for example, the average transmission data rate of each terminal can be applied. In this case, after determining the first weighting factor W1 according to the transmission power of the i-th terminal in Step 532 of the uplink resource allocation processing routine 500, the second weighting factor is determined according to the average transmission data rate of the i-th terminal. W2 is determined, and a weighting factor W obtained by multiplication of W1 and W2 may be given to the i-th terminal.

  The value of the average transmission data rate necessary for determining the first weighting factor W1 is stored as other information 1427 in the resource allocation request management table 142. Each terminal may notify the value of the average transmission data rate to the base station 10 by a resource allocation request. However, each time the base station 10 receives a resource allocation request, for example, the number of requested frequency blocks ( It may be calculated from the accumulated value of the transmission buffer level) and the number of requests.

  When an OFDMA / CDMA terminal transmits a large amount of data by CDMA, the influence (interference) on other terminals that transmit data by CDMA increases, so if the average transmission data rate exceeds a predetermined threshold, the second The value of the weighting factor is set to be larger than “1” so that the scheduling priority of OFDMA resource allocation of the i-th terminal is higher than that of other terminals having the same transmission power. According to the present embodiment, when the average transmission data rate is the same, the first weighting factor W1 gives a higher priority to a terminal having higher transmission power, so that interference in the CDMA region is reduced, and An OFDMA resource can be assigned with priority given to a terminal having a poor radio wave propagation environment.

  As a parameter for determining the second weighting factor W2, for example, the value of the QoS class 1123 may be used. In this case, the higher the QoS class is, the higher the value of the second weighting factor W2 is set so that the value of W2 exceeds “1” in the QoS class exceeding the threshold class. According to the present embodiment, it is possible to assign OFDMA resources in consideration of QoS and radio wave propagation environment.

  According to the present invention, in a radio communication system that supports both OFDMA and CDMA, resource allocation that optimizes the trade-off between the communication quality in the radio section and the number of terminals that can be accommodated in the base station is possible.

1 is a configuration diagram of a mobile radio communication system to which the present invention is applied. FIG. 1A conceptually shows multiple connections in an OFDMA communication system, and FIG. 2B shows the relationship between OFDMA frequency resources and time resources. Fig. (A) schematically shows a mobile radio system that supports both OFDMA and CDMA, and Fig. (B) shows the relationship between frequency resources (vertical axis) and time resources (horizontal axis). The block block diagram which shows one Example of the terminal device 30 with which this invention is applied. The figure which shows the detail of the OFDM control part 300 of the terminal device 30, the OFDM transmission circuit 320, and the OFDM receiving circuit 330. The figure which shows one Example of the OFDM control part 100 of the base station 10 to which this invention is applied, the OFDM transmission circuit 120, and the OFDM receiving circuit 130. FIG. The figure which shows an example of the terminal (MS) management table 140 with which the base station 10 is provided. The figure which shows an example of the resource management table 141 with which the base station 10 is provided. The figure which shows one example of the resource allocation request | requirement management table 142 with which the base station 10 is provided. The figure which shows an example of the communication sequence performed between the terminal device 30 and the base station 10. FIG. The flowchart which shows 1st Example of the allocation process routine 500 of the uplink resource which the base station 10 (OFDM control part 100) performs. The flowchart of the used resource determination processing routine 600 which the terminal 30 (OFDM control part 300) performs. The flowchart of the CDMA resource optimization process routine 530 which the base station 10 (OFDM control part 100) performs regularly. The flowchart which shows 2nd Example of the uplink resource allocation processing routine 500 which the base station 10 (OFDM control part 100) performs.

Explanation of symbols

10: base station, 20: base station control device, 30: wireless terminal device, 31: protocol processing unit, 110, 310: wireless transmission / reception circuit, 100, 300: OFDM control unit, 120, 320: OFDM transmission circuit, 121, 321: Encoder, 122, 322: Modulator, 123, 323: Subcarrier mapping unit, 124, 324: IDFT unit, 125, 325: Control symbol adding unit, 326: CDM multiplexing unit, 130, 330: OFDM reception circuit,
131, 331: DFT part, 132, 332: Subcarrier demapping part,
133, 333: Demodulator, 134, 334: Decoder, 135: CDMA receiver,
140: Terminal (MS) management table, 141: Resource management table, 142: Resource allocation request management table, 326: CDMA multiplexing unit.

Claims (21)

A base station having an orthogonal frequency division multiple access (OFDMA) communication function and a code division multiple access (CDMA) communication function, and a plurality of terminal apparatuses that communicate with the base station wirelessly. A first type terminal that transmits uplink data to the station by OFDMA and transmits a control signal by CDMA, and a second type terminal that can transmit uplink data by either OFDMA or CDMA and transmits a control signal by CDMA In a wireless communication system in which devices coexist,
The base station has an OFDM controller that manages uplink radio communication resources by dividing them into OFDMA resources and CDMA resources, and executes resource allocation in response to resource allocation requests from each terminal device,
The OFDM control unit includes resource optimization means for dynamically changing a ratio of OFDMA resources and CDMA resources constituting the uplink radio communication resource according to the usage rate of OFDMA resources, and issues the resource allocation request Resource allocation is performed for each reference period, and when there is a shortage of free OFDMA resources with respect to the total amount of requested resources, priority is given to the allocation of OFDMA resources to the first type terminal apparatus, Suppresses the allocation of OFDMA resources to the second type terminal apparatus, and determines whether to transmit the uplink data by CDMA or retransmit the resource allocation request to the base station when allocation of the OFDMA resources fails And performing an operation corresponding to the determination result . The wireless communication system according to claim 1, wherein
Resources in which the OFDM control unit defines the uplink radio communication resources in a plurality of time / frequency regions, and stores them in a time / frequency region that becomes the OFDMA resource and a time / frequency region that becomes the CDMA resource A wireless communication system comprising a management table, managing a use state of an OFDMA resource by the resource management table, and changing a ratio between the OFDMA resource and the CDMA resource. The wireless communication system according to claim 2,
The OFDM control unit divides the uplink radio communication resource into a plurality of time slots within a reference period and a plurality of frequency blocks each including a plurality of carriers, and each time / frequency region is divided on the resource management table. Defined by the time slot and the frequency block. The wireless communication system according to claim 1, wherein
The resource optimization unit of the OFDM control unit increases the CDMA resource to decrease the OFDMA resource when the usage rate of the OFDMA resource is equal to or less than a first threshold, and the usage rate of the OFDMA resource is: The wireless communication system, wherein when the second threshold value larger than the first threshold value is exceeded, the CDMA resource is decreased and the OFDMA resource is increased. The wireless communication system according to claim 1, wherein
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the transmission power of the first type terminal device and the second type terminal device is equal to or greater than a predetermined threshold. A wireless communication system that performs OFDMA resource allocation scheduling for an existing terminal device . The wireless communication system according to claim 1 , wherein
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the OFDM control unit gives a reference weight coefficient to the first type terminal apparatus, and sets the transmission power to the second type terminal apparatus. A wireless communication system characterized by assigning a corresponding weighting factor and executing OFDMA resource allocation scheduling according to the priority weighted by the weighting factor . The wireless communication system according to claim 1 , wherein
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the OFDM control unit gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. And a weighting factor corresponding to the average transmission data rate, and performing OFDMA resource allocation scheduling according to the priority weighted by the weighting factor. The wireless communication system according to claim 1 , wherein
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the OFDM control unit gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. A wireless communication system, which assigns a weighting factor according to the requested QoS and executes OFDMA resource allocation scheduling according to the priority weighted by the weighting factor. A first type terminal device that transmits uplink data by orthogonal frequency division multiple access (OFDMA) and a control signal by code division multiple access (CDMA), and can transmit uplink data by either OFDMA or CDMA. A base station for a mobile radio communication system that communicates with a plurality of terminal apparatuses including a second type terminal apparatus that transmits CDMA by CDMA,
An uplink radio communication resource is managed by dividing it into OFDMA resources and CDMA resources, and has an OFDM control unit that executes resource allocation in response to a resource allocation request from each terminal device,
The OFDM control unit includes resource optimization means for dynamically changing a ratio of OFDMA resources and CDMA resources constituting the uplink radio communication resource according to the usage rate of OFDMA resources, and issues the resource allocation request Resource allocation is performed for each reference period, and when there is a shortage of free OFDMA resources with respect to the total amount of requested resources, priority is given to the allocation of OFDMA resources to the first type terminal apparatus, Suppresses the allocation of OFDMA resources to the second type terminal apparatus, and determines whether to transmit the uplink data by CDMA or retransmit the resource allocation request to the base station when allocation of the OFDMA resources fails And execute the action corresponding to the judgment result
A base station characterized by that . In the base station according to claim 9,
Resources in which the OFDM control unit defines the uplink radio communication resources in a plurality of time / frequency regions, and stores them in a time / frequency region that becomes the OFDMA resource and a time / frequency region that becomes the CDMA resource A base station having a management table, managing a use state of an OFDMA resource by the resource management table, and changing a ratio between the OFDMA resource and the CDMA resource . The base station according to claim 10,
The resource optimization unit of the OFDM control unit increases the CDMA resource to decrease the OFDMA resource when the usage rate of the OFDMA resource is equal to or less than a first threshold, and the usage rate of the OFDMA resource is: The base station , wherein when the second threshold value larger than the first threshold value is exceeded, the CDMA resource is decreased and the OFDMA resource is increased . In the base station according to claim 9 ,
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the transmission power of the first type terminal device and the second type terminal device is equal to or greater than a predetermined threshold. A base station that performs scheduling of OFDMA resource allocation for a terminal device . In the base station according to claim 9 ,
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources , the OFDM control unit gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. A base station that assigns a weighting factor according to the above and performs OFDMA resource allocation scheduling according to the priority weighted by the weighting factor . In the base station according to claim 9 ,
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the OFDM control unit gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. And a weighting factor corresponding to the average transmission data rate, and performing scheduling of OFDMA resource allocation according to the priority weighted by the weighting factor . In the base station according to claim 9 ,
When the OFDM control unit runs out of free OFDMA resources with respect to the total amount of the requested resources, the OFDM control unit gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. A base station which assigns a weighting factor according to the requested QoS and executes OFDMA resource allocation scheduling according to the priority weighted by the weighting factor. A base station having an orthogonal frequency division multiple access (OFDMA) communication function and a code division multiple access (CDMA) communication function, and a plurality of terminal apparatuses that communicate with the base station wirelessly. A first type terminal that transmits uplink data to the station by OFDMA and transmits a control signal by CDMA, and a second type terminal that can transmit uplink data by either OFDMA or CDMA and transmits a control signal by CDMA In a radio resource allocation method in a radio communication system in which devices coexist ,
The base station managing the use state of uplink radio resources separately for OFDMA resources and CDMA resources;
Broadcasting CDMA resources for uplink data transmission from the base station to each terminal device;
Transmitting a resource allocation request from any of the terminal devices to the base station;
Upper SL base station calculates the total amount of requests resources for each reference period, when OFDMA resources idle is insufficient, giving priority to the allocation of OFDMA resources to the first type of the terminal device, the second type Suppressing allocation of OFDMA resources to the terminal device, executing resource allocation scheduling, and transmitting a notification message indicating a resource allocation result to the terminal device that has issued the resource allocation request;
A terminal device that has successfully allocated OFDMA resources transmits uplink data to the base station using the OFDMA resource specified in the notification message;
When the terminal device that has failed to allocate OFDMA resources is the second type, it is determined whether transmission data is transmitted by CDMA or a resource allocation request is retransmitted to the base station, and an operation corresponding to the determination result is executed. A method for assigning radio resources, comprising: steps . The radio resource allocation method according to claim 16 ,
When the base station runs out of free OFDMA resources with respect to the total amount of the requested resources, the transmission power of the first type terminal device and the second type terminal device becomes a predetermined threshold or more. A radio resource allocation method , wherein the scheduling of the allocation of OFDMA resources is executed for a terminal device . The radio resource allocation method according to claim 16 ,
When the base station runs out of free OFDMA resources with respect to the total amount of the requested resources, the base station assigns a reference weighting factor to the first type terminal device, and transmits a transmission power to the second type terminal device. A radio resource allocation method , comprising: assigning a corresponding weight coefficient, and performing the OFDMA resource allocation scheduling according to the priority weighted by the weight coefficient . The radio resource allocation method according to claim 16 ,
When the base station runs out of free OFDMA resources with respect to the total amount of the requested resources, the base station gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. A radio resource allocation method, comprising: assigning a weighting factor according to an average transmission data rate, and performing allocation scheduling of the OFDMA resource according to a priority weighted by the weighting factor . The radio resource allocation method according to claim 16 ,
When the base station runs out of free OFDMA resources with respect to the total amount of the requested resources, the base station gives a reference weight coefficient to the first type terminal apparatus, and transmits transmission power to the second type terminal apparatus. A radio resource allocation method comprising: assigning a weighting factor according to a requested QoS, and performing allocation scheduling of the OFDMA resource according to a priority weighted by the weighting factor. In the radio | wireless resource allocation method in any one of Claims 16-20 ,
A radio resource allocation method comprising: a step in which the base station changes a ratio of OFDMA resources and CDMA resources constituting the uplink radio communication resource in accordance with an OFDMA resource usage rate .

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