JP5081614B2 - Wireless base station, mobile station, wireless communication system, and wireless communication method - Google Patents

Description

  The present invention relates to a radio base station, a mobile station, a radio communication system, and a radio communication method.

Conventionally, a mobile communication system using OFDMA (Orthogonal Frequency Division Multiple Access) that realizes multiple access between a radio base station and a mobile station by dividing a carrier signal into a plurality of orthogonal subcarriers is known. ing. The details of this communication method are described in Non-Patent Document 1 below. As a channel allocation method in a mobile communication system using OFDMA, there are two methods shown in FIGS. 15 (a) and 15 (b). In the method shown in FIG. 15A, subcarriers of the same frequency band are allocated to the sectors S ₁ , S ₂ , and S ₃ of one radio base station, and in the method shown in FIG. It is logically divided into three segments, and subcarriers belonging to the divided segments are allocated to adjacent sectors S ₁ , S ₂ , S ₃ .

Further, the cell C ₁ corresponding to one radio base station is divided into an outer area A ₁ and an inner area A _2, and all subcarriers that can be transmitted are transmitted to the inner area A ₂ with less interference with other cells. allocation, to the large outer area a ₁ of the interference with other cells, channel allocation method that allocates a portion of the subcarriers segmentation is disclosed (see Patent Document 1 and FIG. 16).
Japanese Patent Laid-Open No. 2005-80286 “IEEE Standard for Local and metropolitan area networks Part 16: AirInterface for Fixed and Mobile Broadband Wireless Access Systems Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and MobileOperation in Licensed Bands and Corrigendum 1”, IEEE Std, February 2006

  Among the above methods, the method in which subcarriers in the same frequency band are allocated to each sector uses the entire transmittable band, so that throughput can be improved. However, interference with adjacent cells is large, and at the cell boundary. Communication quality tends to deteriorate. On the other hand, the method of segmenting the frequency band has the advantage that interference with adjacent cells is small, but tends to reduce the throughput. In particular, when using OFDMA compliant with IEEE802.16e, the data length of DL-MAP and UL-MAP, which are control signals in a radio frame, increases in proportion to the number of users of the mobile station. As it increases, the problem of reduced throughput becomes more prominent.

  In addition, the allocation method described in Patent Document 1 tries to prevent a decrease in throughput by allocating all frequency bands in the inner region, but the user data part in the radio frame is defined as the outer region of the cell. Since it is necessary to divide the inner region into two in terms of time, the improvement in throughput is not so large.

  Therefore, the present invention has been made in view of such a problem, a radio base station capable of realizing reduction in inter-cell interference and improvement in maximum throughput, and improvement in utilization efficiency of frequency space, It is an object to provide a mobile station, a wireless communication system, and a wireless communication method.

  In order to solve the above problems, a radio base station according to the present invention is a multiplex that generates time-division multiplexed user data in a radio base station that transmits radio signals to and from a plurality of mobile stations by orthogonal frequency division multiple access. And a plurality of subcarriers selected from a plurality of subcarriers distributed on the frequency axis, and a radio frame including a subchannel allocated to each of the plurality of sets of subcarriers is configured. Channel allocation control means for setting the user data and control data related to setting of user data in the radio frame by time division multiplexing, and transmission means for transmitting a radio signal including the radio frame, the channel allocation control means, Then, all subchannels in the radio frame are divided into areas for each transmission destination sector of the radio signal, and control data is divided into the divided areas. Stores are configured and to store user data on all the sub-channels in the radio frame.

  Alternatively, the radio communication method of the present invention is a radio communication method in which a radio base station transmits radio signals to / from a plurality of mobile stations by orthogonal frequency division multiple access. And a channel assignment control means that selects a plurality of subcarriers from a plurality of subcarriers distributed on the frequency axis, and assigns a subchannel assigned to each of the plurality of subcarriers. A channel assignment control step that configures a radio frame including the user data in the radio frame and control data related to user data setting in the radio frame by time-division multiplexing, and a radio signal including the radio frame And a channel assignment control step that transmits all subchannels in the radio frame. It is divided into areas of destination sectors of the line signal, and stores the control data in the divided corresponding area, and stores the user data on all the sub-channels in the radio frame.

  According to such a radio base station and radio communication method, a radio frame including subchannels assigned to a plurality of sets of subcarriers is configured, and user data and the user data in the radio frame are included in the radio frame. Control data related to the setting is set by time division multiplexing, and a radio signal including the radio frame is transmitted to the mobile station. At that time, the subchannel in the radio frame is divided into areas for each transmission destination sector, the control data is stored in the divided areas, and the user data is stored on all the subchannels. It is possible to prevent the loss of control data on the mobile station side due to the interference to ensure the reception quality related to the user data, and at the same time to improve the throughput when transmitting the user data.

  The channel allocation control means sets first storage location information for specifying a storage location of control data in the radio frame, and a second address indicating a storage start position of user data in the radio frame in the control data It is preferable to set information and storage type information indicating that user data is stored on all subchannels. With such channel assignment control means, the radio base station notifies the mobile station of the control data storage location in the divided area in the radio frame by using the first storage location information, and the second address information and storage location. The storage start position and storage range of user data can be notified by the type information. As a result, the control data and user data can be reliably extracted from the range of different subchannels in the radio channel on the mobile station side.

  The channel assignment control means receives a request signal for network connection transmitted from the mobile station, and the data set in the radio frame of the request signal is set in the sub-channel divided area. If the user data is stored in the corresponding area divided by the subchannel in the radio signal for the mobile station, and the data is set on all the subchannels in the radio frame, the radio for the mobile station It is also preferred to store user data on all subchannels in the radio frame of the signal. With this configuration, the data storage area in the request signal received from the mobile station is determined, and user data is set for all subchannels according to the data storage area, or the subchannel area is divided. Can be determined. As a result, it is possible to realize reception quality related to user data and improve throughput while adapting to the function on the mobile station side.

  Further, the channel assignment control means, in the process of generating a subchannel composed of a plurality of sets of subcarriers in a radio frame, a subcarrier for transmitting a pilot signal for estimating radio quality for each transmission destination sector. It is also preferable that the transmission means transmit a radio signal including a radio frame in which a pilot signal is set. In this way, even if user data is stored and transmitted on all subchannels regardless of the transmission destination sector, the pilot signal transmission subcarriers are transmitted in different arrangements for each transmission destination sector in the radio frame. Interference of pilot signals between adjacent transmission destination sectors can be prevented. As a result, it is possible to improve the throughput at the time of user data transmission and at the same time improve the estimation accuracy of the communication quality on the user data receiving side.

  Further, the channel assignment control means selects a subchannel by determining a selection order from a plurality of subcarriers based on pre-assigned cell identification information, and transmits a pilot signal for estimating radio quality. It is also preferable that the subcarriers to be configured are set to have different arrangements for each cell identification information, and the transmission means transmits a radio signal including a radio frame in which a pilot signal is set. In this case, even if user data is stored and transmitted on all subchannels regardless of the transmission destination sector, the pilot signal is transmitted in a different arrangement for each cell identification information in the radio frame. Pilot signal interference can be prevented. As a result, it is possible to improve the throughput at the time of user data transmission and at the same time improve the estimation accuracy of the communication quality on the user data receiving side.

  The mobile station of the present invention is a mobile station that receives a radio signal with a radio base station by orthogonal frequency division multiple access, for each of a plurality of sets of subcarriers selected from a plurality of subcarriers distributed on the frequency axis. Receiving means for receiving a radio signal including a radio frame composed of subchannels assigned to the radio base station, control data relating to setting of user data in the radio frame from the radio frame, and time-division multiplexed user data Channel allocation analysis means for extracting, the channel allocation analysis means divides all subchannels in the radio frame into areas for each transmission destination sector of the radio base station, takes out the control data from the corresponding area corresponding to its own device, The user data is extracted from all subchannels in the radio frame.

  According to the mobile station configured as described above, a radio signal is received from a radio base station, and the radio signal includes a radio frame having subchannels assigned to each of a plurality of sets of subcarriers. Data and control data related to setting of the user data in the radio frame are set by time division multiplexing. Since the control data is extracted from the corresponding areas of the divided subchannels in the received radio frame and user data is extracted from all the subchannels in the radio frame, the mobile station side caused by interference between cells In this way, it is possible to prevent the loss of control data and to secure the reception quality related to user data, and at the same time, improve the throughput when transmitting user data.

  Channel allocation control means for setting uplink data in a time domain different from control data and user data set by a radio base station in a radio frame, and transmission means for transmitting a radio signal including a radio frame in the time domain, The channel allocation control means sets subcarriers for transmitting a pilot signal for estimating the radio quality so as to be arranged differently for each transmission destination sector specified from the control data. It is preferable to transmit a radio signal including a radio frame in the time domain in which is set. With this configuration, even if uplink data is stored and transmitted on all subchannels regardless of the transmission destination sector, the pilot signal transmission subcarriers are transmitted in different arrangements for each transmission destination sector in the radio frame. Therefore, pilot signal interference between adjacent transmission destination sectors can be prevented. As a result, it is possible to improve the communication quality estimation accuracy on the uplink data receiving side.

  The wireless communication system of the present invention includes the above-described wireless base station and mobile station.

  Alternatively, the radio communication method of the present invention is a radio communication method in which a radio base station and a mobile station transmit and receive radio signals by orthogonal frequency division multiple access, and the radio base station generates time-division multiplexed user data. A multiplexing step; a radio base station selects a plurality of subcarriers from a plurality of subcarriers distributed on a frequency axis, and transmits a radio frame including a subchannel assigned to each of the plurality of subcarriers. A channel assignment control step configured to time-multiplex and set user data and control data related to user data setting in the radio frame in the radio frame, and the radio base station transmits a radio signal including the radio frame A transmission step, a reception step in which the mobile station receives a radio signal from the radio base station, and a mobile station from the radio frame to the radio frame. A channel allocation analysis step for extracting control data relating to user data settings in the frame and time-division multiplexed user data, and in the channel allocation control step, all subchannels in the radio frame are transmitted to the destination sector of the radio signal. The control data is stored in each divided area, the user data is stored on all the subchannels in the radio frame, and the channel assignment analysis step corresponds to the own apparatus in the radio frame. Control data is extracted from the corresponding area, and user data is extracted from all subchannels in the radio frame.

  According to such a radio communication system and radio communication method, a radio frame including subchannels allocated to a plurality of sets of subcarriers is configured, and user data and the user data in the radio frame are included in the radio frame. Control data related to the setting is set by time division multiplexing, and a radio signal including the radio frame is transmitted to the mobile station. At that time, the subchannel in the radio frame is divided into areas for each transmission destination sector, the control data is stored in the divided areas, and the user data is stored on all the subchannels. On the other hand, a radio signal is received from the radio base station by the mobile station, control data is extracted from the corresponding area of the divided subchannel in the received radio frame, and the user is transmitted from all subchannels in the radio frame. Since the data is extracted, it is possible to prevent the loss of control data on the mobile station side due to the interference between the cells to ensure the reception quality related to the user data, and at the same time to improve the throughput when transmitting the user data.

  According to the present invention, it is possible to reduce the inter-cell interference and improve the maximum throughput, thereby improving the frequency space utilization efficiency.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a wireless communication system and a wireless communication method according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  1 and 2 are schematic configuration diagrams of a radio base station 10 and a mobile station 20, respectively, according to a preferred embodiment of the present invention. The radio communication system according to the present embodiment includes a plurality of radio base stations 10 and a plurality of mobile stations 20, and is an orthogonal frequency division multiple access (OFDMA) compliant with IEEE802.16e. This is a communication system for transmitting and receiving radio signals between the radio base station 10 and the mobile station 20 using. OFDMA is a type of multicarrier transmission in which the entire band of a transmission carrier is divided into subcarriers on the frequency axis, and a radio signal is transmitted as a bundle of a plurality of narrowband subcarriers. For example, 5 MHz, 10 MHz, or 20 MHz is selected as the bandwidth of the transmission carrier. First, functional configurations of the radio base station 10 and the mobile station 20 will be described in detail.

As shown in FIG. 1, the radio base station 10 includes an error correction encoding unit 11 _{1 to} 11 _N , a modulation unit 12 _{1 to} 12 _N , a multiplexing unit (multiplexing unit) 13, a channel allocation control unit (channel allocation control). Means) 14, an OFDM signal generation section 15, and a transmission section (transmission means) 16. Each of target information to be transmitted to a plurality of mobile stations 20, is subjected to error correction coding processing by error correction coding unit 11 ₁ to 11 _N, is output from each of the error correction coding unit 11 ₁ to 11 _N The redundant bit information after the error correction encoding process is generated as user data that is time-division multiplexed via the modulators 12 _{1 to} 12 _N and the multiplexer 13. The user data output from the multiplexing unit 13 is set in a radio frame by the channel assignment control unit 14, and the radio frame is converted into a radio signal for OFDMA by the OFDM signal generation unit 15, and the radio signal is Transmitted by the transmitter 16 to the external mobile station 20 using OFDMA. Here, the radio base station 10 can transmit separate radio signals to three sectors in a cell, which is an area where radio communication with the mobile station 20 is possible.

  The channel assignment control unit 14 creates a radio frame by assigning a channel in the radio frame as follows. FIG. 3A conceptually shows the data arrangement on the time axis and the frequency axis of the radio frame created by the channel assignment control unit 14. The channel assignment control unit 14 assigns channels on a predetermined basis for each subchannel logical number shown in FIG. Specifically, a plurality of sets of subcarriers are selected from a plurality of subcarriers distributed on the frequency axis within a frequency band in which the radio base station 10 can transmit. Then, a radio channel is configured by assigning a subchannel identified by a subchannel logical number to each of the plurality of subcarrier groups.

Furthermore, the channel assignment control unit 14 stores a downlink data DL for storing data transmitted from the radio base station 10 to the mobile station 20 and an uplink for storing data transmitted from the mobile station 20 to the radio base station 10. It is generated by being separated in time into the part UL. The downlink unit DL includes a preamble unit D _P for synchronizing radio frames on the receiving side, a control data unit D _C for controlling data reading for each sector in the radio frame, and a plurality of mobile stations. user data part D _U for storing user data is arranged. FIG. 3 (b) is a conceptual diagram illustrating in greater detail the data sequence on the time axis and the frequency axis of the control data part D _C of the radio frame. As shown in the figure, the control data section D _C is the user data in the subchannel specified by the frame control header _(FCH) D C1, FCH for specifying the subchannel to be used for each sector in the radio frame DL-MAP indicating the setting area includes mapping information _{D C2,} such as UL-MAP.

Therefore, the channel assignment control part 14, a control data part D _C of the radio frame, sets the time division multiplexing as follows. That is, by using PUSC (Pertial Usage of Sub Channels) as a frequency division allocation method for each sector, subchannels included in the entire band Sp allocated to the radio frame are subchannel groups f ₁ that are six logical groups. Are divided into ˜f ₆ (see FIG. 4), and two sub-channel groups among the sub-channel groups f _{1 to} f ₆ are allocated to the three sectors. Then, the channel assignment control part 14 based on the destination sector, sets the control data part D _C in the region of the corresponding sub-channel group in the radio frame. FIG. 5 shows subchannel groups f ₁ and f ₄ for transmission destination sector S ₁ , subchannel groups f ₂ and f ₅ for transmission destination sector S ₂ , and subchannel groups f ₂ and f ₅ for transmission destination sector S ₃ . channel group f _3, f _6, respectively, example allocated as an area for setting the control data part D _C is shown. Channel assignment control part 14, when setting the control data part _{D C} includes a frame control header _D C1 based on the information output from the multiplexing unit 13, DL-MAP, the mapping information including the UL-MAP, etc. after estimating the size of the D _C2, to determine the capacity of the storage destination of the region, determining a temporal position of the separator between the control data part D _C and the user data part D _U. Then, the channel assignment control unit 14 embeds the information that specifies the setting position of the frame control header D _C1 in the preamble part D _P, the sub-channel groups belonging to areas assigned to the destination sector in the frame control header D _C1 by embedding identifying information (first resource allocation information), to allow extraction of the control data part D _C of the mobile station 20 side.

The channel assignment control part 14, after setting the control data part D _C, the user data output from the multiplexing unit 13, the user data portion region is defined on all the sub-channels included in the radio frame the D _U, when storing by division multiplexing. The channel assignment control part 14, the DL-MAP contained in mapping information D _C2 in the control data section D _C, the information indicating the storage start position of user data, all the sub-channels of user data in the radio frame The information indicating that it is stored above is set in advance, and the storage area of the user data on the mobile station 20 side can be specified by these information. FIG. 6 is a diagram illustrating an example of the configuration of data set in the DL-MAP included in the mapping information _DC2 , in the data item “OFDMA symbol offset” of the data type “Zone Switch IE” in the DL-MAP. storage start position of user data, i.e., information identifying a separation position between the control data part D _C and the user data part D _U is set, the data item "Use all SC indicator" area of all the sub-channels is user data A value “1” indicating that the data is stored in is set. As a result, the mobile station 20 on the receiving side can be notified that the user data unit _DU is expanded on all subchannels.

Next, moving to FIG. 2, the mobile station 20 includes a reception unit (reception unit) 21, an OFDM signal detection unit 22, a channel allocation analysis unit (channel allocation analysis unit) 23, a demodulation unit 24, and an error correction decoding unit 25. have. The reception unit 21 receives a radio signal including a radio frame transmitted from the radio base station using OFDMA, and the received radio signal is detected by the OFDM signal detection unit 22 so that the radio frame is generated from the radio signal. Is taken out. From the radio frame retrieved after the control data part D _C is taken out by the channel assignment analysis part 23, by which the control data unit D _C is analyzed, the user data is taken further from the radio frame . The user data is demodulated from the time-division multiplexed data by the demodulator 24, and then subjected to error correction decoding processing by the error correction decoder 25 to be restored to information addressed to the mobile station 20.

  The channel allocation analysis unit 23 analyzes the radio frame output from the OFDM signal detection unit 22 by allocating subchannels as follows. That is, the channel allocation analysis unit 23 allocates subchannels for each subchannel logical number according to the same criteria as the radio base station 10. Specifically, a plurality of subcarrier groups are selected from a plurality of subcarriers distributed on the frequency axis within the frequency band of the carrier signal of the radio base station 10. Then, a radio channel is analyzed by assigning a subchannel identified by a subchannel logical number to each of the plurality of subcarrier groups.

Then, the channel assignment analysis part 23 reads the preamble part D _P of the radio frame, the preamble portion frame control of the control data section D _C on the basis of the information written in the D _P header D _{C1 (Fig.} 3 (b) ). Then, based on the first storage location information included in the frame control header _DC1 , an area composed of two subchannel groups assigned to the sector in which the device is located is specified, and the area is determined from the radio frame. Split. For example, when the mobile station 20 is located in the sector S ₁ , the area including the subchannel groups f ₁ and f ₄ is divided from the radio frame (FIG. 5). Then, the channel assignment analysis part 23 takes out mapping information _{D C2,} including a DL-MAP and UL-MAP from the divided regions. Then, the channel assignment analysis part 23, the part of the data item "OFDMA symbol offset" from DL-MAP, and read the portion of the data item "Use All SC indicator", the start position of the user data part D _U from the information At the same time, it is determined that the user data unit _DU is expanded on all the subchannels in the radio frame.

Furthermore, the channel assignment analysis part 23, after interpreting the control data part D _C, from the user data part D _U set in the area including all the sub-channels in the radio frame, user data for the mobile station 20 It is taken out and output to the demodulator 24. In this case, the channel assignment analysis part 23 can identify the setting area of the user data of the mobile station 20 for in the user data part D _U, from DL-MAP contained in mapping information D _C2.

  Next, with reference to FIG. 7, the operation of the radio communication system including the radio base station 10 and the mobile station 20 will be described, and the radio communication method in the radio communication system will be described in detail. FIG. 7 is a sequence diagram showing an operation when user data is transmitted from the radio base station 10 to the mobile station 20 in the radio communication system.

As shown in the figure, first, when information to be transmitted from the wireless communication network to the mobile station 20 is received in the wireless base station 10, the error correction encoding units 11 _{1 to} 11 _N of the wireless base station 10 The information is subjected to error correction coding processing (step S01). The redundant bit information generated by the error correction coding process is modulated by the modulation units 12 _{1 to} 12 _N (step S02), and further multiplexed by the multiplexing unit 13 (step S02). S03), generated as time-division multiplexed user data.

Next, the channel assignment control unit 14 sets an area including two subchannel groups corresponding to the transmission destination sector (step S04). Then, the channel assignment control part 14, based on the information output from the multiplexing unit 13 estimates the size of the control data part D _C (step S05). Furthermore, the channel assignment control part 14, the control data section _{D C} of the radio frame, and stores the frame control header _{D C1} and mapping information _{D C2} (step S06). After setting the control data part D _C, the channel assignment control unit 14 stores the user data on all the sub-channels of the radio frame (step S07). Then, the OFDM signal generation unit 15 generates a radio signal for OFDMA, and the radio signal is transmitted to the mobile station 20 by the transmission unit 16 (step S08).

On the other hand, a radio signal is received by the receiving unit 21 of the mobile station 20, and this radio signal is detected by the OFDM signal detecting unit 22, whereby a radio frame is extracted from the radio signal (step S09). The channel allocation analysis unit 23 sequentially extracts a preamble part D _P , a frame control header D _C1 in the control data part D _C , and mapping information D _C2 from this radio frame (step S10). Then, the channel assignment analysis part 23, by interpreting DL-MAP of the mapping information D _C2, taken from the user data part D _U that is deployed user data on all the sub-channels in the radio frame (step S11) .

  The user data thus extracted is demodulated as redundant bit information from the time-division multiplexed data by the demodulator 24 (step S12). Then, the redundant bit information is subjected to error correction decoding processing by the error correction decoding unit 25 and restored to the original information (step S13). Finally, a desired process is performed on this information by an application program in the mobile station 20 (step S14).

According to the radio communication system and the radio communication method described above, a radio frame including subchannels assigned to a plurality of sets of subcarriers is configured, and user data and the user data in the radio frame are included in the radio frame. Control data such as the frame control header D _C1 , DL-MAP, and UL-MAP regarding the setting is set by time division multiplexing, and a radio signal including the radio frame is transmitted to the mobile station 20. At that time, the subchannel in the radio frame is divided into areas for each transmission destination sector, the control data is stored in the divided areas, and the user data is stored on all the subchannels. On the other hand, a radio signal is received from the radio base station 10 by the mobile station 20, control data is extracted from the corresponding area of the divided subchannel in the received radio frame, and all the subchannels in the radio frame are extracted. The user data is retrieved from. Therefore, it is possible to prevent the loss of control data on the mobile station side due to the interference between cells and to secure the reception quality related to the user data, and at the same time to improve the throughput at the time of user data transmission. That is, compared with the conventional case where both control data and user data are set in a divided area in a radio frame, it is possible to achieve both prevention of the influence of inter-cell interference and improvement of throughput.

  In addition, this invention is not limited to embodiment mentioned above. For example, the radio base station 10 may operate so as to determine whether to divide the user data setting area in the radio frame according to the function of the mobile station 20.

  In this case, the radio base station 10 determines from the mobile station 20 to the radio base station 10 at the time of network connection request processing (Initial Ranging) whether or not the function of the mobile station 20 supports only three divisions of radio frames. This can be determined by the transmitted request signal. FIG. 8 is a sequence diagram showing a procedure for requesting network connection from the mobile station 20 to the radio base station 10. The channel assignment control unit 14 of the radio base station 10 receives a radio frame including the CDMA code transmitted from the mobile station 20 in this procedure. If user data including a CDMA code is set on all subchannels in the radio frame, user data is set on all subchannels in a radio frame transmitted to the mobile station 20 thereafter. To do. On the other hand, if user data is set in the subchannel area divided into three in the received radio frame, the subchannel corresponding to the transmission destination sector in the radio frame transmitted to the mobile station 20 thereafter User data is set in the three divided areas (FIG. 9). Thereby, the data storage area in the request signal received from the mobile station 20 is determined, and the user data is set in all the subchannels according to the data storage area, or is set in the divided subchannel area. It is possible to determine whether or not to perform reception, and it is possible to prevent reception data from being lost in the mobile station by adapting to the function on the mobile station side.

  In addition, the radio base station 10 and the mobile station 20 transmit a pilot signal for estimating radio quality in a radio frame to be transmitted / received by using a plurality of subcarriers in the radio frame. You may set a subcarrier so that it may become a different arrangement | positioning for every sector or a cell. 10 and 11 are schematic configuration diagrams of the radio base station 10A and the mobile station 20A, which are modifications of the present invention in this case. Hereinafter, components of the radio base station 10A and the mobile station 20A will be described focusing on differences from the radio base station 10 and the mobile station 20.

Referring to FIG. 10, the radio base station 10A includes a reception unit 117, an OFDM signal detection unit 118, a channel allocation analysis unit 119, a separation unit 120, demodulation units 121 _{1 to} 121 _N , and error correction decoding units 122 _{1 to} 122. _N is further included. The reception unit 117 receives a radio signal including a frame transmitted at the time of UL shown in FIG. 3A from the mobile station 20A using OFDMA, and the received radio signal is received by the OFDM signal detection unit 118. As a result of detection, a radio frame is extracted from the radio signal. The uplink radio frame UL, the downlink radio frame DL control data section D _C and the user data part D _U in the radio frame are set are assigned to different time domain (see FIG. 3 (a)) . That is, the mobile station 20A transmits uplink user data at a region designated by the control data part D _C in the downlink transmitted from the radio base station 10A the radio frame DL (refer to Figure 3 (a)). In this way, user data transmitted from a plurality of mobile stations including the mobile station 20A in different areas is transmitted by the channel assignment analysis unit 119 of the base station 10A from the plurality of mobile stations including the mobile station 20A. Retrieved as data. The uplink user data is separated into uplink user data for each mobile station including the mobile station 20A by the separation unit 120, demodulated by the demodulation units 121 _{1 to} 121 _N , and then error-corrected decoding units 122 _{1 to} 122 _N. Error correction decoding processing is performed to restore the uplink user data for each mobile station.

  Further, the channel allocation analysis unit 119 analyzes the pilot signal set in the uplink radio frame UL in the radio frame, and determines the communication quality of the radio environment with the mobile station 20A based on the received power of the pilot signal. It can also be estimated. The estimation result of the communication quality can be used for transmission power control of a radio signal transmitted / received to / from the mobile station 20A.

  The channel assignment control unit 114 divides a plurality of subcarriers into a predetermined number of consecutive subcarrier combinations called clusters in the process of assigning and generating subchannels in a radio frame. For example, when the number of subcarriers in the frequency band that can be transmitted by the radio base station 10A is 840, the subcarrier is divided into clusters composed of 14 consecutive subcarriers. Channel assignment control section 114 then replaces the arrangement of the divided clusters, then selects an arbitrary subcarrier from each cluster and assigns it to one subchannel. Each subchannel is given a subchannel logical number.

  Further, the channel assignment control unit 114 sets a pilot signal for estimating the radio quality on the mobile station 20A side in the radio frame in the process of generating the radio frame by assigning the subchannel as described above. That is, channel assignment control section 114 sets a predetermined subcarrier in the cluster as a pilot signal transmission subcarrier at the time of cluster creation. The pilot signal transmission subcarriers may be arranged differently for even symbols and odd symbols as shown in FIGS. 12 (a), (b), and (c). Specifically, the channel allocation control unit 114 refers to a parameter Segment ID used to identify a transmission destination sector when allocating a subchannel, and when Segment ID = “0”, “1”, “2” Thus, as shown in FIGS. 12 (a), (b), and (c), the pilot signals are set to be differently arranged. In the figure, it is shown that pilot signals are set at positions indicated by hatching in odd-numbered symbols and even-numbered symbols on 14 subcarriers divided into clusters. A radio signal including a radio frame in which a pilot signal is set is transmitted by the transmitter 16 toward the mobile station 20A.

  Note that the channel assignment control unit 114 can also set the arrangement of pilot signal transmission subcarriers to be different for each cell. That is, when assigning subcarriers to a radio frame, the channel assignment control unit 114 determines a selection order of sub-channels of a plurality of clusters for each cell based on a parameter ID cell (cell identification information) assigned in advance. A plurality of subchannels are selected. In addition, the channel assignment control unit 114 refers to the parameter IDcell, and in the case of IDcell = “0”, “1”, “2”, respectively, in FIGS. 12A, 12B, and 12C, respectively. As shown, the pilot signals are set so as to have different arrangements. Since parameter IDcell can take a value of 0 to 31, for example, the allocation of pilot signals can be changed for each cell by assigning different parameter IDcells to each cell in advance.

  Referring to FIG. 11, mobile station 20A includes error correction coding section 126, modulation section 127, channel allocation control section (channel allocation control means) 128, OFDM signal generation section 129, and transmission section (transmission means) 130. In addition. The information to be transmitted to the radio base station 10A is subjected to error correction coding processing by the error correction coding unit 126, and the redundant bit information output from the error correction coding unit 126 is subjected to data modulation by the modulation unit 127. Generated as uplink user data. The uplink user data output from the modulation unit 127 is set in a radio frame by the channel allocation control unit 128, and the radio frame is converted into a radio signal for OFDMA by the OFDM signal generation unit 129. The transmission unit 130 transmits the signal to the radio base station 10A using OFDMA.

Here, the channel allocation control unit 128 allocates a plurality of subcarriers to a subchannel in the same manner as the channel allocation control unit 114 of the radio base station 10A, and what is a downlink radio frame DL on the subchannel? Uplink user data is set in the uplink radio frame UL (FIG. 3A) in different time domains. The channel allocation control unit 128, by referring to the parameter Segment ID for specifying the destination sector embedded in the transmitted preamble part D _P from the radio base station 10A, from the uplink radio frame UL in the radio frame A combination of a plurality of symbols is selected for each transmission destination sector, and a pilot signal is embedded on the selected plurality of symbols. Specifically, when the PUSC is adopted as the subcarrier allocation method, the channel allocation control unit 114 is shown in the case of the parameter Segment ID = “0”, “1”, “2”, respectively. 13 (a), (b), and (c) are set so that the arrangement of pilot signals is different. In addition, the channel allocation control unit 114 adopts OPUSC (Optional PUSC) as the subcarrier allocation method, and in the case of the parameter Segment ID = “0”, “1”, “2”, respectively, As shown in FIGS. 14 (a), 14 (b), and 14 (c), the pilot signals are set differently. FIG. 13 and FIG. 14 show the arrangement of pilot signal transmission subcarriers in tiles created in the process of mapping subchannels to uplink radio signals. That is, it is indicated by diagonal lines in symbols of the 0th to 2nd digits on 4 (or 3) consecutive subcarriers divided into tiles that are a set of a plurality of continuous subcarriers and symbols of the subcarriers. The pilot signal is set at the position.

  Further, the channel allocation analysis unit 123 analyzes the pilot signal set in the downlink radio frame DL in the radio frame, and based on the received power of the pilot signal, the communication quality of the radio environment with the radio base station 10A Can also be estimated. The estimation result of the communication quality can be used for transmission power control of a radio signal transmitted / received to / from the radio base station 10A.

  According to such radio base station 10A and mobile station 20A, even if user data is stored and transmitted on all subchannels irrespective of the transmission destination sector or cell, the pilot signal transmission subcarriers are included in the radio frame. Therefore, it is possible to prevent interference of pilot signals between adjacent transmission destination sectors or cells. As a result, it is possible to improve the throughput at the time of user data transmission and at the same time improve the estimation accuracy of the communication quality on the user data receiving side.

It is a schematic block diagram of the radio base station concerning suitable one Embodiment of this invention. It is a schematic block diagram of the mobile station concerning suitable one Embodiment of this invention. It is a conceptual diagram which shows the data arrangement on the time-axis and frequency axis of the radio | wireless frame which the channel allocation control part of FIG. 1 produces. It is a figure which shows the image after the division | segmentation of a subchannel. FIG. 2 is a conceptual diagram showing a radio frame created for each transmission destination sector by the radio base station of FIG. 1. It is a figure which shows an example of a data structure of the mapping information of FIG. It is a sequence diagram which shows operation | movement of the radio | wireless communications system concerning this embodiment. FIG. 3 is a sequence diagram showing a procedure when a network connection is requested from the mobile station of FIG. 2 to the radio base station 10 of FIG. 1. It is a conceptual diagram which shows the radio | wireless frame which the radio base station which is a modification of this invention produces. It is a schematic block diagram of the radio base station concerning the modification of this invention. It is a schematic block diagram of the mobile station concerning the modification of this invention. FIG. 11 is a diagram illustrating an arrangement image of pilot signals in a set of a plurality of consecutive subcarriers and symbols in a radio frame by the radio base station of FIG. 10. FIG. 12 is a diagram showing an arrangement image of pilot signals in a set of a plurality of consecutive subcarriers and symbols in a radio frame by the mobile station of FIG. 11. FIG. 12 is a diagram showing an arrangement image of pilot signals in a set of a plurality of consecutive subcarriers and symbols in a radio frame by the mobile station of FIG. 11. It is a figure which shows the frequency band of the carrier for every sector in the conventional radio | wireless communications system. It is a figure which shows the cell structure of the conventional radio | wireless communications system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,10A ... Wireless base station, 13 ... Multiplexing part (multiplexing means), 14, 114, 128 ... Channel allocation control part (channel allocation control means), 16, 130 ... Transmitting part (transmitting means), 20, 20a ... mobile station, 21 ... receiving unit (receiving unit), 23, 123 ... channel allocation analyzing unit (channel allocation analyzing unit).

Claims (10)

In a radio base station that transmits radio signals to and from a plurality of mobile stations by orthogonal frequency division multiple access,
Multiplexing means for generating time-division multiplexed user data;
A plurality of subcarriers are selected from a plurality of subcarriers distributed on the frequency axis, a radio frame including a subchannel assigned to each of the plurality of subcarriers is configured, and the user is included in the radio frame. Channel allocation control means for setting data and control data related to setting of the user data in the radio frame by time division multiplexing;
Transmission means for transmitting a radio signal including the radio frame,
The channel allocation control means divides all the subchannels in the radio frame into areas for each transmission destination sector of the radio signal, stores the control data in the divided corresponding areas, and stores the user data in the area Configured to store on all the subchannels in a radio frame;
A wireless base station characterized by that. The channel assignment control means sets first storage location information for specifying the storage location of the control data in the radio frame, and starts storing the user data in the radio frame in the control data Setting second address information indicating a location and storage type information indicating that the user data is stored on all the subchannels;
The radio base station according to claim 1. The channel assignment control means receives a request signal for network connection transmitted from the mobile station, and data set in a radio frame of the request signal is set in a sub-channel divided area. If the user data is stored in the corresponding region divided into subchannels in the radio signal for the mobile station, and the data is set on all subchannels in the radio frame, Storing the user data on all subchannels in a radio frame of the radio signal for the mobile station;
The radio base station according to claim 1 or 2, characterized in that The channel allocation control means is configured to transmit a subcarrier for transmitting a pilot signal for estimating radio quality in the process of generating the subchannel composed of the plurality of sets of subcarriers in the radio frame. Set to be different for each destination sector,
The transmission means transmits a radio signal including a radio frame in which the pilot signal is set;
The radio base station according to any one of claims 1 to 3. The channel allocation control means selects the subchannel by determining a selection order from the plurality of subcarriers based on pre-assigned cell identification information, and transmits a pilot signal for estimating radio quality Subcarriers to be set to be different for each cell identification information,
The transmission means transmits a radio signal including a radio frame in which the pilot signal is set;
The radio base station according to any one of claims 1 to 3. In a mobile station that receives a radio signal with a radio base station by orthogonal frequency division multiple access,
Receiving means for receiving, from the radio base station, a radio signal including a radio frame composed of subchannels assigned to a plurality of sets of subcarriers selected from a plurality of subcarriers distributed on a frequency axis;
Channel allocation analyzing means for extracting control data related to setting of user data in the radio frame and the user data time-division multiplexed from the radio frame,
The channel allocation analysis means divides all the subchannels in the radio frame into areas for each transmission destination sector of the radio base station, extracts the control data from the corresponding area corresponding to the own device, and the user data Is extracted from all the subchannels in the radio frame,
A mobile station characterized by that. Channel allocation control means for setting uplink data in a different time domain from the control data and the user data set by the radio base station in the radio frame;
Further comprising a transmission means for transmitting a radio signal including the time domain radio frame,
The channel allocation control means sets subcarriers for transmitting a pilot signal for estimating radio quality so as to be arranged differently for each transmission destination sector specified from the control data,
The transmission means transmits a radio signal including a radio frame in the time domain in which the pilot signal is set;
The mobile station according to claim 6.   A radio communication system comprising the radio base station according to claim 1 and the mobile station according to claim 6. In a radio communication method in which a radio base station transmits radio signals to / from a plurality of mobile stations by orthogonal frequency division multiple access,
A multiplexing step in which multiplexing means generates user data that is time-division multiplexed;
The channel assignment control means selects a plurality of sets of subcarriers from a plurality of subcarriers distributed on the frequency axis, and configures a radio frame including subchannels assigned to the plurality of sets of subcarriers. A channel assignment control step for setting the user data in the radio frame and control data related to the setting of the user data in the radio frame by time division multiplexing; and
A transmitting means for transmitting a radio signal including the radio frame,
In the channel assignment control step, all the subchannels in the radio frame are divided into areas for each transmission sector of the radio signal, the control data is stored in the divided areas, and the user data is Storing on all the subchannels in a radio frame;
A wireless communication method. In a radio communication method in which a radio base station and a mobile station transmit and receive radio signals by orthogonal frequency division multiple access,
A multiplexing step in which the radio base station generates user data that is time-division multiplexed;
The radio base station selects a plurality of subcarriers from a plurality of subcarriers distributed on the frequency axis, and configures a radio frame including subchannels assigned to the plurality of subcarriers. A channel assignment control step for setting the user data in the radio frame and control data related to the setting of the user data in the radio frame by time division multiplexing; and
The wireless base station transmits a wireless signal including the wireless frame; and
The mobile station receives the radio signal from the radio base station; and
The mobile station comprises a channel allocation analysis step for extracting control data related to setting of user data in the radio frame and the user data time-division multiplexed from the radio frame,
In the channel assignment control step, all the subchannels in the radio frame are divided into areas for each transmission sector of the radio signal, the control data is stored in the divided areas, and the user data is Storing on all the subchannels in the radio frame;
In the channel allocation analysis step, the control data is extracted from a corresponding region corresponding to the own device in the radio frame, and the user data is extracted from all the subchannels in the radio frame.
A wireless communication method.

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