JP4434717B2 - Mobile communication system, base station and mobile station of the system - Google Patents

Description

  The present invention relates to a mobile communication system in which radio resources used for data transmission are shared by a plurality of mobile stations, and more particularly to a mobile communication system that performs handover control, a base station of the system, and a mobile station.

  In a cellular communication system in which a base station transmits data to multiple mobile stations, there is a cell selection method in which the mobile station selects a base station (see, for example, Patent Document 1). This Patent Document 1 has the following disclosure.

In a cellular communication system in which a base station transmits data to multiple mobile stations, the load on the cell of the base station depends on the number of mobile stations and the data rate of each mobile station. In this cellular communication system, when the mobile station apparatus selects a cell with a heavy load, when the mobile station apparatus starts communication with the cell, an undesirably large increase in interference may occur. This is due to the fact that interference increases nonlinearly with the cell load. Furthermore, adding a mobile station device to a cell that is already heavily loaded may cause the cell to reach its loading threshold. This can result, for example, in a loss of connectivity, removing mobile stations from the cell, reducing the data rate of some mobile stations, or increasing system delay due to packet buffering. In order to overcome the above problem, the base station of the cellular communication system measures the degree of congestion in the cell of the base station, and transmits the measurement value of the degree of congestion to the mobile station apparatus. The mobile station apparatus selects a cell for data transmission based on the received measurement value of the degree of congestion. Thereby, the mobile station apparatus can select a base station with a low congestion degree.
JP 2003-134550 A (page 9-11, FIG. 3 to FIG. 4)

  By the way, in the prior art system described in Patent Document 1 described above, a mobile station selects a base station simply based on the congestion degree of the base station. However, it does not consider how the base station allocates the radio resources of the base station to the mobile station. For example, the base station may allocate radio resources to the mobile station by independently determining the request content, priority, etc. of the mobile station as well as the congestion level.

  In that case, even if the mobile station selects a base station with a low congestion level, the base station does not always preferentially allocate radio resources to the mobile station, and therefore the mobile station does not necessarily secure radio resources. Not exclusively. As a result, there is a problem that the throughput of the mobile station decreases.

  The present invention has been made to solve the above-described problems, and a mobile station selects a base station in consideration of how the base station allocates radio resources of the base station to the mobile station. Accordingly, an object of the present invention is to provide a mobile communication system in which a mobile station can obtain higher throughput, a base station of the system, and a mobile station.

In order to achieve the above object, a mobile communication system of the present invention is a mobile communication system in which radio resources used for data transmission from a base station to a plurality of mobile stations are shared by the plurality of mobile stations, The base station includes: an assignment management unit that manages algorithm type information for determining radio resource allocation to the mobile station; a unit that transmits the algorithm type information to the mobile station; and Means for transmitting a pilot signal for measuring a propagation environment in the downlink direction to the station to the mobile station, and the mobile station receives the algorithm type information transmitted from the plurality of base stations. Receiving power measuring means for receiving the pilot signals transmitted from a plurality of the base stations and measuring a received power parameter, and a plurality of the received powers Based on the plurality of the algorithm type information together with parameters, characterized by comprising a base station selecting means for selecting a base station for transmitting the data from the plurality of the base station.

  According to the present invention, the base station notifies the mobile station of allocation information indicating how radio resources are allocated to the mobile station, and the mobile station allocates radio resources to the mobile station based on the allocation information. The mobile station can obtain a higher throughput by selecting a base station that can be used.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 7 show an embodiment in which the present invention is applied to a mobile communication system, FIG. 1 is a configuration diagram of the mobile communication system, FIG. 2 is a block diagram showing a detailed configuration of a base station, and FIG. 3 is a mobile station It is a block diagram which shows the detailed structure of these. 4 to 7 are flowcharts showing the operations of the base station and the mobile station in the first to fourth embodiments, respectively.

  FIG. 1 shows a configuration diagram of an example of a mobile communication system in a handover state. The base station 1 covers the cell range 1f, and the base station 2 covers the cell range 2f. Since the mobile station 11 is located in the cell range 1f, the mobile station 11 is connected to the base station 1. Since the mobile station 12 is located at the boundary between the cell range 1f and the cell range 2f, a handover state is formed between the base station 1 and the base station 2. The mobile station 13 is connected to the base station 2 because it is located in the cell range 1f.

  The base station 1 includes a pilot channel 1a, a broadcast channel 1b, a data transmission channel 1c shared by a plurality of mobile stations (a radio resource used for data transmission), a control channel 1d associated with the data transmission channel, and each mobile The individual channel 1e transmitted separately to the station is transmitted. The base station 2 includes a pilot channel 2a, a broadcast channel 2b, a data transmission channel 2c shared by a plurality of mobile stations (a radio resource used for data transmission), a control channel 2d associated with the data transmission channel, and each mobile station The individual channel 2e transmitted separately to the station is transmitted.

  The data transmission channel 1c and the data transmission channel 2c are channels used for data transmission typified by a high-speed downlink packet transmission method (HSDPA: High-Speed Downlink Packet Access), and are shared by each mobile station.

(Assignment of data transmission channel to each mobile station by base station)
Each base station transmits information related to allocation of a data transmission channel to each mobile station to the mobile station through one or more of a broadcast channel, a control channel, and a dedicated channel. This allocation information indicates the criteria and algorithm used when the base station allocates a data transmission channel to each mobile station. For example, “priority is given to a mobile station having a good propagation environment”, “performs real-time service” "Mobile stations have priority".

  In addition, each base station transmits a pilot signal to the mobile station through the pilot channel, and the mobile station receives this and measures the received power parameter, and the propagation environment parameter in the downlink direction from the base station to the mobile station. Is calculated.

(Base station selection by mobile station)
The mobile station 12 during handover obtains information on assignments transmitted by the base station 1 and base station 2 that are base stations (hereinafter referred to as active sets) during handover, and obtains information on assignments advantageous to the own station. A base station, that is, a base station that preferentially allocates a data transmission channel to the own station is selected.

  The mobile station 12 receives the pilot signals of the pilot channels 1a and 2a transmitted by the base station 1 and the base station 2 which are the base stations of the active set, measures the reception level thereof, and receives the respective reception power parameters. Measure. This means a downlink propagation environment, which means confirming a base station that can perform stable downlink data transmission.

  If the difference between the received power parameters of the base station 1 and the base station 2 is within a predetermined threshold, the mobile station 12 transmits data to the mobile station 2 based on the information regarding the assignment, not the magnitude of the received power parameter. A base station (hereinafter referred to as a primary base station) to perform is selected. This makes it possible to select a base station that can obtain higher throughput.

  For example, when the mobile station 12 selects the base station 1 as the primary base station, the base station 1 is the base station that is the base station 1 using the uplink control channel 12a with the ID of the base station 1 as the primary base station ID. 1 and the base station 2 are notified.

  Upon receiving this notification, the base station 1 recognizes that the own station is the primary base station of the mobile station 12. Data transmission to the mobile station 12 and the mobile station 11 located in the cell range 1f is performed in a time-sharing manner by sharing the data transmission channel 1c. In the example of FIG. 1B, data transmission to the mobile station 11 is performed at timings T1, T4, and T5, and data transmission to the mobile station 12 is performed at timings T2, T3, and T6 based on internal determination of the base station 1. .

  On the other hand, the base station 2 recognizes that the own station is not the primary base station of the mobile station 12. Accordingly, as shown in FIG. 1C, the base station 2 performs data transmission only to the mobile station 13 through the data transmission channel 2c at all timings T1 to T6.

  FIG. 2 is a block diagram showing a detailed configuration of the base station. The main part of the base station includes an antenna 41, a radio processing unit 42, a reception processing unit 43, a transmission processing unit 44, a control unit 45, and the like.

  The wireless processing unit 42, the reception processing unit 43, and the transmission processing unit 44 are usually realized using an ASIC or a DSP. The control unit 45 is usually realized using a CPU or DSP. In general, a part of the reception processing unit 43 and the transmission processing unit 44 is configured for each mobile station that is a communication target (the chain line portion in FIG. 2).

  Next, functions of each unit of the base station will be described. A radio signal transmitted from the mobile station is received by the antenna 41 and transmitted to the radio processing unit 42. The wireless processing unit 42 performs wireless processing such as down-conversion and A / D conversion on the received wireless signal, and sends the converted signal to the synchronization processing unit 431 and the signal processing unit 432.

  The synchronization processing unit 431 performs timing synchronization on the received signal, and sends an optimal reception timing signal to the signal processing unit 432. The signal processing unit 432 uses the reception timing signal output from the synchronization processing unit 43 to perform signal processing such as transmission path compensation and demodulation processing on the converted radio signal. The separation processing unit 433 separates the radio signal subjected to signal processing by the signal processing unit 432 into a signal processed in bit units and a signal processed in coding units. Then, a signal processed in bit units is sent to the control unit 45. In addition, a signal processed in a coding unit is sent to the decoding processing unit 434. The decoding processing unit 434 performs decoding processing such as turbo decoding or Viterbi decoding on the signal output from the separation processing unit 433, and sends the decoded data to the control unit 45.

  The mobile station information management unit 451 of the control unit 45 uses the information from the mobile station, the number of mobile stations that have selected the base station during handover, the downlink propagation environment information for each mobile station, and each mobile station The mobile station information such as the confirmation response information for the data is managed and sent to the allocation management unit 452 as necessary.

  The allocation management unit 452 determines the allocation of the data transmission channel to the mobile stations sharing the data transmission channel according to an arbitrary algorithm, and based on the information notified from the mobile station information management unit 451, the data transmission channel Manage information about assignments. Information on allocation includes the number of mobile stations sharing the data transmission channel, average downlink propagation environment information of all mobile stations, average data rate information of all mobile stations, algorithms for determining allocation, etc. Manage one or more.

  In addition, information regarding these assignments is notified to the control signal generation unit 455 and the notification signal generation unit 456. Note that mobile station information and information related to allocation are stored in the storage unit 453.

  Next, the transmission process will be described. The information signal generation unit 454 sends the data generated for each mobile station to the encoding processing unit 443. The control signal generation unit 455 sends a signal processed in bit units to the multiprocessing unit 442 and sends a signal processed in coding units to the encoding processing unit 443. The broadcast signal generation unit 456 sends a broadcast signal to be broadcast to all mobile stations to the encoding processing unit 445. Pilot signal generation section 457 sends pilot signals for all mobile stations to signal processing section 444.

  The encoding processing unit 443 performs encoding processing such as turbo encoding or convolutional encoding on the transmission signal transmitted from the control unit 45 and transmits the transmission signal to the multiplex processing unit 442. The multiplexing processing unit 442 multiplexes the encoded transmission signal and the control signal transmitted from the control signal generation unit 455 and transmits the multiplexed signal to the signal processing unit 441. The signal processing unit 441 performs predetermined signal processing such as modulation processing on the input transmission signal. The encoding processing unit 445 performs encoding processing such as turbo encoding and convolutional encoding on the transmission signal transmitted from the control unit 45 and transmits the transmission signal to the signal processing unit 444. The signal processing unit 444 performs predetermined signal processing such as modulation processing on the input transmission signal. The transmission signals sent from the signal processing unit 441 and the signal processing unit 444 are multiplexed and sent to the wireless processing unit 42.

  The wireless processing unit 42 performs wireless processing such as D / A conversion and up-conversion on the input transmission signal, generates a wireless signal, and sends it to the antenna 41. The antenna 41 transmits a radio signal to the mobile station.

  FIG. 3 is a block diagram showing a detailed configuration of the mobile station. The main part of the mobile station includes an antenna 51, a radio processing unit 52, a reception processing unit 53, a transmission processing unit 54, a control unit 55, and the like. The wireless processing unit 52, the reception processing unit 53, and the transmission processing unit 54 are usually realized using an ASIC or a DSP. The control unit 55 is usually realized using a CPU or a DSP.

  Next, functions of each unit of the mobile station will be described. A radio signal transmitted from the base station is received by the antenna 51 and transmitted to the radio processing unit 52. The wireless processing unit 52 performs wireless processing such as down-conversion and A / D conversion on the received wireless signal, and sends the converted signal to the synchronization processing unit 531 and the signal processing unit 532.

  The synchronization processing unit 531 synchronizes timing with the received signal, and sends an optimal reception timing signal to the signal processing unit 532. The signal processing unit 532 uses the reception timing signal output from the synchronization processing unit 43 to perform signal processing such as transmission path compensation and demodulation processing on the converted wireless signal. The separation processing unit 533 extracts a pilot signal from the radio signal subjected to the signal processing by the signal processing unit 532 and transmits the pilot signal to the control unit 55. The data signal is extracted and sent to the decoding processing unit 534. The decoding processing unit 534 performs decoding processing such as turbo decoding or Viterbi decoding on the signal output from the separation processing unit 533, and sends the decoded data to the control unit 55.

  The power measurement unit 551 of the control unit 55 uses the pilot signal output from the separation processing unit 533 to measure reception power parameters such as reception power, desired signal power to interference signal power ratio (SIR), and propagation loss. . The allocation information extraction unit 552 extracts allocation parameters notified from the base station. The base station selection unit 553 determines a base station to select using the received power parameter and the allocation parameter. The storage unit 554 stores selection candidate (active set) base station information, measured received power parameters, allocation parameters, and the like.

  The encoding processing unit 543 performs encoding processing such as turbo encoding or convolutional encoding on the transmission signal transmitted from the control unit 55 and transmits the transmission signal to the multiplex processing unit 542. Multiplexing section 542 multiplexes the encoded transmission signal and a control signal including base station selection information determined by base station selecting section 553 and sends the multiplexed signal to signal processing section 541. The signal processing unit 541 performs predetermined signal processing such as modulation processing on the input transmission signal, and sends the signal to the wireless processing unit 52.

  The wireless processing unit 52 performs wireless processing such as D / A conversion and up-conversion on the input transmission signal, generates a wireless signal, and sends it to the antenna 51. The antenna 51 transmits a radio signal to the base station.

  FIG. 4 is a flowchart illustrating control of the base station and the mobile station in the first embodiment. The operation of the first embodiment of the mobile communication system will be described with reference to FIGS. 4 and 1 to 3.

  In FIG. 1, it is assumed that the mobile station 12 in the handover state has not yet decided from which data transmission channel of the base station the data transmission is performed. Further, it is assumed that there are a total of five mobile stations including the mobile station 11 and other mobile stations (not shown) that perform communication sharing the data transmission channel 1c within the cell range 1f of the base station 1. On the other hand, it is assumed that there are a total of two mobile stations performing communication sharing the data transmission channel 2c, including the mobile station 13 and other mobile stations not shown in the cell range 2f of the base station 2.

  In this state, the allocation management unit 452 (FIG. 2) of the control unit 45 of the base station 1 manages the number of mobile stations sharing the data transmission channel 1c as information regarding data transmission channel allocation (FIG. 2). 4 step S1). This “number of shared mobile stations = 5” is obtained via the control signal generation unit 455, the encoding processing unit 443, the multiplexing processing unit 442, the signal processing unit 441, the wireless processing unit 42, and the antenna 41. Then, it is transmitted as a radio signal to the mobile station (step S2).

  Also, the pilot signal generation unit 457 of the base station 1 creates pilot signals for all mobile stations, and constantly transmits them as radio signals from the antenna 41 to all mobile stations via the signal processing unit 444 and the radio processing unit 42. (Not shown in FIG. 4).

  On the other hand, the base station 2 similarly transmits “the number of mobile stations sharing the data transmission channel = 2c” as a radio signal to the mobile station as information regarding the allocation of the data transmission channel of the base station 2. (Steps S1 and S2 in FIG. 4). Also, the pilot signal of the base station 2 is always transmitted to all mobile stations (not shown in FIG. 4).

  In the mobile station 12 (FIG. 3) in the handover state, the antenna 51 receives the radio signal of “the number of shared mobile stations” from the base station 1 and the base station 2 which are active cells, and the radio processing unit 52 The data is sent to the allocation information extraction unit 552 via the synchronization processing unit 531, the signal processing unit 532, the separation processing unit 533, and the decoding processing unit 534. Then, the allocation information extraction unit 552 extracts the “number of shared mobile stations” of each base station, the “number of shared mobile stations = 5” of the base station 1, and the “shared mobile station” of the base station 2. Mobile station number = 2 ”is obtained (step S11 in FIG. 4). The “number of shared mobile stations” of each base station is sent to the base station selection unit 553.

  Further, the mobile station 12 receives radio signals of pilot signals from the base station 1 and the base station 2 which are active cells by the antenna 51, and performs a radio processing unit 52, a synchronization processing unit 531, a signal processing unit 532, and a separation process. It is sent to the power measuring unit 551 via the unit 533. Then, the power measurement unit 551 measures the received power parameters such as the received power, the desired signal power to interference signal power ratio (SIR), the propagation loss, and the like using the pilot signal of each base station. The propagation environment is calculated (step S12 in FIG. 4). For example, it is assumed that the received power parameter is the same for the base station 1 and the base station 2 or that the base station 1 is slightly better than the base station 2. The reception power parameter of each base station is sent to the base station selection unit 553.

  Then, the base station selection unit 553 determines that the received power parameter is the same between the base station 1 and the base station 2 or that the base station 1 is slightly better than the base station 2, that is, the downlink from the base station to the mobile station 12 When the difference in direction propagation environment is a predetermined threshold, the base station 2 which is a base station having a small number of “shared mobile stations” of each base station transmits a primary base station that performs data transmission to the mobile station 12 (Step S13).

  Next, the primary base station ID indicating the base station 2 is transmitted to the base station 1 and the base station 2 via the encoding processing unit 543, the multiplexing processing unit 542, the signal processing unit 541, the wireless processing unit 52, and the antenna 51. As a radio signal (step S14).

  In the base station 1, the radio signal of the primary base station ID indicating the base station 2 is received by the antenna 41, and the radio processing unit 42, the synchronization processing unit 431, the signal processing unit 432, the separation processing unit 433, and the decoding processing unit 434 are transmitted. Via, it is sent to the mobile station information management unit 451, and the primary base station ID indicating the base station 2 is recognized (step S3).

  The mobile station information management unit 451 of the base station 1 does not match the primary base station ID indicating the base station 2 and the ID of the base station 1, so that the mobile station 12 has selected the base station 1. It is determined that there is not (NO in step S4). Then, data transmission to five mobile stations including the mobile station 11 sharing the data transmission channel 1c and other mobile stations (not shown) is continued as it is (step S6).

  On the other hand, the base station 2 similarly recognizes the primary base station ID indicating the base station 2 (step S3). Then, the mobile station information management unit 451 of the base station 2 matches the primary base station ID indicating the base station 2 with the ID of the base station 2, so that the mobile station 12 selects the base station 2 (YES in step S4).

  Next, the allocation management unit 452 of the base station 2 manages three, including the mobile station 13 sharing the data transmission channel 2c and other mobile stations (not shown) plus the mobile station 12. The data to be individually transmitted to each of the three mobile stations is time-divisionally transmitted via the data processing channel via the encoding processing unit 445, the signal processing unit 444, the wireless processing unit 42, and the antenna 41. A signal is transmitted to each mobile station (step S5).

  In the mobile station 12, the radio signal of the transmission data is received by the antenna 51, and passes through the radio processing unit 52, the synchronization processing unit 531, the signal processing unit 532, the separation processing unit 533, and the decoding processing unit 534, and the control unit The data is sent to 55 and data for the mobile station 12 is received (step S15).

  In the example described above, the base station notifies the mobile station of “the number of shared mobile stations”, and the mobile station uses the “number of shared mobile stations” and the received power parameter of the base station. , Select a base station. That is, the mobile station is an algorithm that selects a base station with a small number of “shared mobile stations” even if the received power parameter is a little inferior.

  In this way, the mobile station 12 selects the base station 2 with “the number of shared mobile stations = 2” so that the base station 2 has the number of shared mobile stations = 2 + 1 + 1 = 3. And “1/3” of the data transmission channel 2 c is allocated to the mobile station 12. Higher throughput can be obtained compared to “1/6” when the base station 1 having “the number of shared mobile stations = 5” is selected.

  Note that “the number of shared mobile stations” can be converted into a coefficient to simplify the base station selection process in the mobile station. For example, the base station provides a correction coefficient, sets a small correction coefficient when the “number of shared mobile stations” is large, and sets a large correction coefficient when the “number of shared mobile stations” is small. To do. Then, the base station notifies this correction coefficient to the mobile station.

  The base station selection algorithm on the mobile station side is to multiply a received power parameter by a correction coefficient received by the mobile station and select a base station having a larger multiplication result. For example, even if the base station is slightly inferior in the received power parameter, the algorithm selects a base station with a large correction coefficient (a base station with a small number of “shared mobile stations”).

  In this way, the base station notifies the mobile station of a correction coefficient that is a part of information related to the base station selection algorithm on the mobile station side, and the mobile station multiplies the received power parameter by this correction coefficient and multiplies it. By executing the algorithm of selecting the base station with the larger result, it is possible to select a base station that can obtain higher throughput. Also, the base station selection processing algorithm in the mobile station can be a simple algorithm that selects the multiplication and the larger one of the multiplication results.

  As described above, according to the first embodiment, the mobile station selects the base station that transmits data based only on the propagation environment information by considering the number of shared mobile stations of the radio resource notified from the base station. Compared to the above, it is possible to select a base station that can obtain higher throughput.

  FIG. 5 is a flowchart illustrating control of the base station and the mobile station in the second embodiment. With reference to FIG. 5 and FIGS. 1 to 3, the operation of the second embodiment of the mobile communication system will be described focusing on the differences from the first embodiment.

  The base station stores, in the storage unit 453 (FIG. 2), an algorithm type for determining how to allocate to a mobile station sharing a data transmission channel that is a radio resource. The allocation management unit 452 reads this information from the storage unit 453 (step S21 in FIG. 5), and transmits it to the mobile station via a predetermined circuit in FIG. 2 as in the first embodiment (step S22). .

  For example, the base station 1 transmits “prioritize a mobile station with good downlink propagation environment” as an algorithm type to the mobile station, and the base station 2 moves “prioritize a mobile station performing real-time service”. Assume that you are transmitting to a station. Further, the base station 1 and the base station 2 transmit pilot signals to the mobile station as in the first embodiment (not shown in FIG. 5).

  In the mobile station 12 (FIG. 3) in the handover state, algorithm type information from each base station is input to the base station selection unit 553 via a predetermined circuit in FIG. 3 (step S31 in FIG. 5). ). Also, the pilot signal from each base station is input to the base station selection unit 553 as a received power parameter via a predetermined circuit in FIG. 3 (step S32 in FIG. 5).

  The base station selection unit 553 confirms the algorithm type information of each base station when the received power parameter is not significantly different between the base station 1 and the base station 2, and the base station selection unit 553 wirelessly transmits to the mobile station 12. Select the base station that will allocate the resources. For example, if the mobile station 12 intends to perform a real-time service such as voice, the base station 2 having the algorithm type information “prioritize the mobile station that performs the real-time service” is selected (step S33).

  Next, a primary base station ID indicating the base station 2 and status information indicating that the mobile station 12 is going to perform a real-time service are transmitted to the base station (step S34).

  The base station 2 receives the primary base station ID indicating the base station 2 (step S23), and since the ID of the base station 2 matches, the mobile station 12 selects the base station 2 (YES in step S24).

  Next, the allocation management unit 452 refers to the status information of each mobile station including the mobile station 12 sharing the data transmission channel 2c. Based on the algorithm type of the base station 2 “prioritize the mobile station that performs the real-time service”, priority is given to the data transmission to the mobile station 12 of the status information indicating that the real-time service is to be performed. The transmission channel 2c is assigned (step S25).

  On the other hand, the base station 1 receives the primary base station ID indicating the base station 2 (step S23), and the mobile station 12 selects the base station 1 because the ID of the base station 1 does not match. It is determined that it is not (NO in step S24).

  Then, the allocation management unit 452 of the base station 1 refers to the status information of each shared mobile station that does not include the mobile station 12, and the “priority is given to a mobile station with good downlink propagation environment” algorithm of the base station 1 Based on the type, data transmission is assigned to the data transmission channel 2c (step S26).

  The mobile station 12 receives the transmission data from the base station 2 (step S35).

  Thus, according to the second embodiment, the mobile station receives from the base station the algorithm type of the base station for determining how to allocate the data transmission channel, which is a radio resource, to the shared mobile station. Considering this, it becomes possible to select a base station that can obtain higher throughput.

  FIG. 6 is a flowchart illustrating control of the base station and the mobile station in the third embodiment. With reference to FIG. 6 and FIGS. 1 to 3, the operation of the third embodiment of the mobile communication system will be described focusing on differences from the first embodiment.

  It is assumed that the base station 1 and the base station 2 perform adaptive modulation / demodulation and adaptive coding (hereinafter referred to as MCS) depending on the downlink propagation environment. When MCS is performed, in order to improve the throughput of the entire system, the base station generally assigns a data transmission channel preferentially to a mobile station having a good downlink propagation environment, and has a high data rate. Means that MCS is being performed. In addition, for a mobile station having a poor downlink propagation environment, data transmission channel allocation has a low priority, which means that MCS is performed at a low data rate.

  The base station 1 and the base station 2 receive notifications of received power parameters that mean the downlink propagation environment from all mobile stations currently sharing the respective data transmission channels, and calculate the average value ( Step S41 in FIG. Then, this average value is transmitted to the mobile station as “average downlink propagation environment information of all mobile stations” (step S42).

  For example, the base station 1 transmits “average downlink propagation environment information of all mobile stations = good” to the mobile station, and the base station 2 sends “average downlink propagation environment information of all mobile stations = poor” ”Is transmitted to the mobile station. Further, the base station 1 and the base station 2 transmit pilot signals to the mobile station as in the first embodiment (not shown in FIG. 6).

  The mobile station 12 in the handover state receives “average downlink propagation environment information of all mobile stations” from each base station (step S51 in FIG. 6). Further, a pilot signal from each base station is received (step S52).

  If the received power parameter is not significantly different between the base station 1 and the base station 2, the base station 2 having “average downlink propagation environment information of all mobile stations = poor” is designated as the primary base station. A station is selected (step S53). This means that the base station 2 is selected because the average data rate of the data transmission channel of the base station 2 is low and the margin is still large. Next, a primary base station ID indicating this base station 2 is transmitted to the base station (step S54).

  The base station 2 receives the primary base station ID indicating the base station 2 (step S43), confirms that the ID of the base station 2 matches, and the mobile station 12 receives the base station 2 Is selected (YES in step S44).

Next, the data to be individually transmitted is time-divided and transmitted to each of the shared mobile stations including the mobile station 12 that shares the data transmission channel 2c (step S45). At this time, since the average data rate of the data transmission channel is low and the margin is still large, the base station 2 can allocate more resources to the mobile station 12. If the average data rate of this data transmission channel is low, it is highly possible that the downlink propagation environment of other mobile stations belonging to the base station 2 is inferior when compared with the mobile station. There is a high probability that more resources are allocated to the mobile station.
The mobile station 12 receives the transmission data from the base station 2 (step S55).

  As described above, according to the third embodiment, the mobile station receives “average downlink propagation environment information of all mobile stations” from the base station and takes it into consideration, whereby higher throughput can be obtained. A base station can be selected.

  FIG. 7 is a flowchart illustrating control of the base station and the mobile station in the fourth embodiment. With reference to FIG. 7 and FIGS. 1 to 3, the operation of the fourth embodiment of the mobile communication system will be described focusing on the differences from the first embodiment.

  It is assumed that the base station 1 and the base station 2 perform adaptive modulation / demodulation and adaptive coding (hereinafter referred to as MCS) depending on the downlink propagation environment. In the case of MCS, the base station variably controls the data rate according to the downlink propagation environment.

  The base station 1 and the base station 2 calculate the average value of the data rates for all the mobile stations sharing the respective data transmission channels at the present time (step S61 in FIG. 7). And the average value of this data rate is notified to a mobile station (step S62). For example, it is assumed that the base station 1 transmits an average value of a high data rate to the mobile station, and the base station 2 transmits an average value of a low data rate to the mobile station.

  Further, the base station 1 and the base station 2 transmit pilot signals to the mobile station as in the first embodiment (not shown in FIG. 7).

  The mobile station 12 in the handover state receives the average data rate from each base station (step S71 in FIG. 7). Further, a pilot signal from each base station is received (step S72). If the received power parameter is not significantly different between the base station 1 and the base station 2, the base station 2 having an average value with a low data rate is selected as the primary base station. (Step S73). Next, the primary base station ID indicating this base station 2 is transmitted to the base station (step S74).

  The base station 2 receives the primary base station ID indicating the base station 2 (step S63), confirms that the ID of the base station 2 matches, and the mobile station 12 receives the base station 2 Is selected (YES in step S64).

Next, the data to be individually transmitted is time-divided and transmitted to each shared mobile station including the mobile station 12 sharing the data transmission channel 2c (step S65). At this time, since the average data rate of the data transmission channel is low and the margin is still large, the base station 2 can allocate more resources to the mobile station 12. If the average data rate of this data transmission channel is low, it is highly possible that the downlink propagation environment of other mobile stations belonging to the base station 2 is inferior when compared with the mobile station. There is a high probability that more resources are allocated to the mobile station.
The mobile station 12 receives the transmission data from the base station 2 (step S75).

  As described above, according to the fourth embodiment, the mobile station receives the average value of the data rate from the base station, and can consider it to select a base station that can obtain higher throughput. Become.

The block diagram of the mobile communication system which concerns on each Example of this invention. The block diagram of the base station which concerns on each Example of this invention. The block diagram of the mobile station which concerns on each Example of this invention. 3 is a flowchart showing operations of a base station and a mobile station in the mobile communication system according to the first embodiment of the present invention. The flowchart which shows operation | movement of the base station of the mobile communication system which concerns on Example 2 of this invention, and a mobile station. The flowchart which shows operation | movement of the base station of the mobile communication system which concerns on Example 3 of this invention, and a mobile station. 7 is a flowchart showing operations of a base station and a mobile station in a mobile communication system according to Embodiment 4 of the present invention.

Explanation of symbols

1, 2 Base station 11, 12, 13 Mobile station 41 Antenna 42 Radio processing unit 43 Reception processing unit 44 Transmission processing unit 45 Control unit 431 Synchronization processing unit 432 Signal processing unit 433 Separation processing unit 434 Decoding processing unit 441 Signal processing unit 442 Multiplexing unit 443 Coding processing unit 444 Signal processing unit 445 Coding processing unit 451 Mobile station information management unit 452 Management unit 453 Storage unit 454 Transmission processing data generation unit 455 Control signal generation unit 456 Notification signal generation unit 457 Pilot signal generation unit 51 Antenna 52 Radio Processing Unit 53 Reception Processing Unit 54 Transmission Processing Unit 55 Control Unit 531 Synchronization Processing Unit 532 Signal Processing Unit 533 Separation Processing Unit 534 Decoding Processing Unit 541 Signal Processing Unit 542 Multiplexing Processing Unit 543 Encoding Processing Unit 551 Power Measurement Unit 552 Allocation information extraction unit 553 Base station selection unit 554 Storage unit

Claims (3)

A mobile communication system in which radio resources used for data transmission from a base station to a plurality of mobile stations are shared by the plurality of mobile stations,
The base station
Assignment management means for managing algorithm type information for determining assignment of radio resources to the mobile station;
Means for transmitting the algorithm type information to the mobile station;
Means for transmitting to the mobile station a pilot signal for measuring a downlink propagation environment from the base station to the mobile station;
The mobile station
Means for receiving the algorithm type information transmitted from a plurality of the base stations;
Received power measuring means for receiving the pilot signals transmitted from a plurality of the base stations and measuring received power parameters;
Base station selection means for selecting a base station to transmit the data from among the plurality of base stations based on a plurality of the algorithm type information together with a plurality of the received power parameters. system. A base station of a mobile communication system in which radio resources used for data transmission from a base station to a plurality of mobile stations are shared by the plurality of mobile stations,
Assignment management means for managing algorithm type information for determining assignment of radio resources to the mobile station;
Means for transmitting the algorithm type information to the mobile station;
A base station of a mobile communication system, comprising: means for transmitting a pilot signal for measuring a downlink propagation environment from the base station to the mobile station to the mobile station. A mobile station of a mobile communication system in which radio resources used for data transmission from a base station to a plurality of mobile stations are shared by the plurality of mobile stations,
Means for receiving algorithm type information for determining assignment of radio resources to the mobile station by the base station transmitted from a plurality of the base stations;
Received power measuring means for receiving the pilot signals transmitted from a plurality of the base stations and measuring received power parameters;
Base station selection means for selecting a base station to transmit the data from among the plurality of base stations based on a plurality of the algorithm type information together with a plurality of the received power parameters. System mobile station.

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