JP2007195102A - Wireless communication system and base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wireless communication system and base station for efficiently executing line allocation of communication lines with a plurality of kinds of bandwidths, in a using frequency band regarding wireless communication utilizing a frequency division multiplex system. <P>SOLUTION: A plurality of frequency slots 19 are provided by dividing a system frequency band 18 usable in the wireless communication system. The communication lines with a plurality of kinds of bandwidths such as a bandwidth A, a bandwidth B, and a bandwidth C are respectively allocated to each frequency slot 19. On that occasion, a communication line with one kind of bandwidth is allocated to one frequency slot 19. The base station executes allocation processing of the communication lines by managing the bandwidth allocated to each frequency slot on a table. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio communication system and a base station that allocate communication lines in a base station in response to a communication line assignment request from a terminal station and perform communication in a system including a base station and a plurality of terminal stations. .

  For example, Japanese Patent Laid-Open No. 8-23297 describes a conventional line allocation method for communication requests having different transmission rates. In this conventional line allocation method, in a communication system consisting of a base station and a plurality of terminal stations, communication lines are allocated between the terminal stations by the base station, such as a low speed call, a medium speed call, and a high speed call. When a base station allocates a communication line in response to a communication request between terminal stations with different transmission rates, one or more low-speed calls are placed on the left end side in the frequency band possessed by the wireless communication system, and one or more are placed in the central portion. Line allocation is performed so that one or more high-speed calls are arranged on the right end side. The base station transmits information on the communication line assigned by this line assignment method to the calling terminal station and the called terminal station, and a communication line is established between the terminal stations.

JP-A-8-23297

  According to the conventional technique described in JP-A-8-23297, the base station performs processing for allocating a band used for a communication line between terminal stations within the frequency band of the wireless communication system. Communication lines are arranged according to certain rules such as a low-speed call from the left end side and a high-speed call from the right end side. According to such an allocation process, although the search time for a free line for a new call is shortened, there is a problem that a restriction is imposed on the arrangement of communication lines. On the other hand, when low-speed calls, medium-speed calls, and high-speed calls are arranged to some extent in a certain position within the frequency band of the wireless communication system, a search for an empty line is started although the restriction on the arrangement of communication lines is small. There is also a problem that the position is complicatedly arranged and the allocation process becomes complicated, and the time required for the search increases.

  The present invention has been made to solve the above-described problems, and relates to wireless communication using a frequency division multiplex system, and efficiently allocates a plurality of types of bandwidth communication lines within a frequency band to be used. An object of the present invention is to obtain a wireless communication system and a base station.

  The wireless communication system according to the invention of claim 1 is a wireless communication system in which a communication line is allocated between a terminal station and a base station, and communication is performed between a plurality of terminal stations and the base station. Receiving a communication line assignment request from the terminal station, transmitting information of the assigned communication line to the terminal station, and communicating with the terminal station via the communication line; and a system frequency band having a plurality of frequency slots And a line assignment control unit that assigns a communication line of one type of bandwidth to each frequency slot and assigns a communication line based on the communication line assignment request.

  A base station according to the invention of claim 2 receives a communication line assignment request from a terminal station, transmits information on the assigned communication line to the terminal station, and communicates with the terminal station via the communication line; A line allocation control unit that divides the system frequency band into a plurality of frequency slots, allocates a communication line of one type of bandwidth to each frequency slot, and allocates a communication line based on the communication line allocation request. It is a thing.

  The wireless communication system according to the invention of claim 3 is a wireless communication system in which a communication line is assigned by a base station based on a communication line assignment request from a terminal station and communication is performed between the terminal stations. A transmitter / receiver that receives a communication line assignment request from the terminal station and transmits information on the assigned communication line to the terminal station, and divides the system frequency band into a plurality of frequency slots, and each frequency slot has one type. A line allocation control unit that allocates a communication line having a bandwidth and allocates a communication line based on the communication line allocation request.

  A base station according to a fourth aspect of the present invention receives a communication channel allocation request from a terminal station, and transmits / receives information of the allocated communication channel to the terminal station, and a system frequency band is divided into a plurality of frequency slots. Each frequency slot includes a line allocation control unit that allocates a communication line of one type of bandwidth and allocates a communication line based on the communication line allocation request.

  According to the present invention, the base station divides a system frequency band into a plurality of frequency slots, assigns a communication line of one type of bandwidth to each frequency slot, and performs communication based on a communication line assignment request from a terminal station. Since line assignment is performed, in the line assignment process, a communication line can be assigned more quickly to an empty area on the system frequency band, and a communication line can be assigned to an arbitrary position on the system frequency area. It is possible to reduce restrictions on communication line allocation processing in which a plurality of types of bandwidths coexist.

Embodiment 1

  A radio communication system according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 is a configuration diagram of a radio communication system according to Embodiment 1 of the present invention. Reference numeral 1 denotes a base station that performs line assignment, and reference numeral 2 denotes a plurality of terminal stations. The plurality of terminal stations 2 are represented as terminal stations 2-1 to 2-N, respectively. A common control line 3 transmits and receives control signals between the base station 1 and the terminal station 2. 4 is a communication line assigned between the base station 1 and each terminal station 2, and is assigned by the base station 1 based on a communication line assignment request transmitted from each terminal station 2 to the base station 1 through the control line 3. A communication line having a different frequency is assigned to each terminal station 2.

  FIG. 2 is a configuration diagram of a radio communication system via a satellite according to the first embodiment of the present invention, and a configuration of a radio communication system that performs communication between the base station 1 and the terminal station 2 through the communication satellite Indicates. In FIG. 2, reference numeral 5 denotes a communication satellite, which is a non-stationary satellite such as a geostationary satellite or an orbiting satellite. In many cases, the communication satellite 5 has a communication transponder and operates as a communication relay station. Therefore, the difference between FIG. 1 and FIG. 2 is whether or not the communication satellite 5 is present on the transmission path viewed from the base station 1 and the terminal station 2, and the control between the base station 1 and the terminal station 2. The communication via the line 3 or the communication line 4 includes communication by the wireless communication system according to both FIG. 1 and FIG.

  FIG. 3 is a configuration diagram of the radio communication system via the satellite according to the first embodiment of the present invention, and shows the configuration of the radio communication system that performs communication between the terminal stations 2. A control signal is transmitted and received between the base station 1 and the terminal station 2 via the control line 3, and a communication line is allocated from the terminal station 2 (calling side terminal station 2) to the base station 1 via the communication satellite 5. A request is transmitted, and line allocation information is transmitted from the base station 1 to the terminal station 2 via the communication satellite 5. The communication line assignment request specifies the called terminal station 2 that is the communication partner, and the base station 1 transmits the line assignment information to both the calling and called terminal stations 2. Based on the line allocation information, communication is performed between the calling terminal station 2 and the called terminal station 2 via the communication line 4.

  Next, the configurations of the base station 1 and the terminal station 2 will be described. 4 is a functional block diagram of a base station according to Embodiment 1 of the present invention, and FIG. 5 is a functional block diagram of a terminal station according to Embodiment 1 of the present invention. In FIG. 4, 6 is an antenna that transmits and receives radio waves, 7 is a transmission / reception circuit that performs high-power amplification of transmission signals, low-noise amplification of reception signals, and synthesis / distribution of transmission / reception signals, and 8 modulates transmission data. The modulation / demodulation unit generates a transmission signal by performing high-frequency conversion, and performs low-frequency conversion and demodulation of the reception signal to generate reception data. Reference numeral 9 denotes a signal processing unit that performs signal processing such as transmission data and reception data encoding (decoding) processing and frame processing. Reference numeral 10 denotes an input / output end point of transmission / reception data transmitted / received by the base station 1. 11 is an allocation of the communication line 4 between the base station 1 and the terminal station 2 based on the communication line allocation request from the terminal station 2 (in the case of the wireless communication system of FIGS. 1 and 2), or between the terminal stations 2 This is a line assignment control unit that performs assignment of the communication line 4 (in the case of the wireless communication system of FIG. 3).

  The base station 1 receives the communication line assignment request signal from the terminal station 2 via the control line 3, and the received line assignment request signal is demodulated by the modem unit 8 and decoded by the signal processing unit 9 for line assignment control. Input to section 11. The line assignment control unit 11 performs processing such as identification of the terminal station 2, extraction and assignment of an empty line, and outputs line assignment information to the signal processing unit 9. The line assignment information is transmitted to the terminal station 2 through the antenna 6 via the control line 3 after undergoing signal processing in the signal processing unit 9, modulation processing / frequency conversion in the modulation / demodulation unit 8, and amplification in the transmission / reception circuit 7. In the wireless communication system shown in FIG. 1 and FIG. 2, since the communication line 4 between the base station 1 and the terminal station 2 is assigned, after the line assignment, the line assignment control unit 11 A line setting command for performing modulation / demodulation processing and frequency conversion of the transmission / reception signal in the assigned communication line 4 is transmitted, and the modulation / demodulation unit 8 performs modulation / demodulation processing and frequency conversion of the transmission / reception signal of the communication line 4 assigned in accordance with this command. In the wireless communication system shown in FIG. 3, since the communication line 4 between the terminal stations 2 is assigned, it is not necessary to transmit / receive the assigned communication line 4 in the base station 1 after the line assignment. The communication state between the terminal stations 2 is monitored by the base station function of the system, and for example, the bandwidth may be changed depending on the quality of the communication line. A line setting command may be sent to the modem unit 8 to monitor the assigned communication line.

  In FIG. 5, 12 is an antenna that transmits and receives radio waves in the terminal station 2, 13 is a transmission / reception circuit that performs high-output amplification of transmission signals, low-noise amplification of reception signals, and synthesis / distribution of transmission / reception signals, 14 A modulation / demodulation unit that modulates transmission data and converts it to high frequency to generate a transmission signal, and converts the reception signal to low frequency and demodulates it to generate reception data. Reference numeral 15 denotes a signal processing unit that performs signal processing such as transmission data and reception data encoding (decoding) processing and frame processing. Reference numeral 16 denotes an input / output end point of transmission / reception data transmitted / received by the terminal station 2. A line control unit 17 generates a communication line assignment request for the base station 1 and instructs the modem unit 14 to set a communication line to be modulated / demodulated based on the line assignment information from the base station 1. Depending on the line setting command of the line control unit 17, the terminal station 2 transmits / receives the communication line 4 between the base station 1 and the terminal station 2 (in the case of the wireless communication system of FIGS. 1 and 2) or the terminal station 2. Transmission / reception on the communication line 4 is started (in the case of the wireless communication system in FIG. 3). The communication line allocation request generated by the line control unit 17 includes the identification number of the own station, the bandwidth or transmission speed necessary for communication, and in the case of the wireless communication system of FIG. This communication line assignment request is subjected to signal processing in the signal processing unit 15, modulation processing / frequency conversion in the modulation / demodulation unit 14, amplification in the transmission / reception circuit, Transmit to station 1. Also, the line allocation information from the base station 1 is received by the antenna 12 and assigned through low noise amplification in the transmission / reception circuit 13, low frequency conversion and demodulation in the modulation / demodulation unit 14, and decoding in the signal processing unit 15. The line information (information such as frequency or channel number, bandwidth or transmission speed) is read, and this line information is input to the line control unit 17.

  Next, the line allocation process in the base station 1 will be described. FIG. 6 is a schematic diagram for explaining frequency allocation in the radio communication system according to Embodiment 1 of the present invention. In FIG. 6, reference numeral 18 denotes the entire frequency band that can be used in the wireless communication system, and this is called the system frequency band. The system frequency band 18 is a frequency band having a finite width allocated to the radio communication system when one radio communication system is constructed. Reference numeral 19 denotes a frequency slot obtained by dividing the system frequency band 18. 20 is a communication line allocated on the frequency slot 19, 20a is a communication line of bandwidth A, 20b is a communication line of bandwidth B, and 20c is a communication line of bandwidth C. In FIG. 6, the bandwidths of communication lines that can be used in the wireless communication system are three types A, B, and C. However, the types of bandwidth are not limited to three types. In the wireless communication system according to the present invention, each terminal station 2 communicates a wide variety of information such as voice, video, and data, and in order to secure a transmission speed necessary for the transmission, in other words, a communication bandwidth. In addition, it is possible to select communication lines having bandwidths A, B, and C different from each other.

  Here, a restriction is imposed on the frequency slot 19 that only a communication line having one of the bandwidths A, B, and C can be allocated. If this restriction is described with reference to FIG. 6, it means that only the communication line having the bandwidth C is arranged in the frequency slot # 1, and only the communication line having the bandwidth B is arranged in the frequency slot # 3. If the system frequency band is divided into three and the number of frequency slots is set to 3, and communication lines with bandwidths A, B, and C are allocated to each, the number of terminal stations 2 that request communication lines with bandwidth C increases. Even if there is no free band in the frequency slot to which the bandwidth C can be allocated, the communication line with the bandwidth C cannot be allocated to the other frequency slots under the above-described restrictions. Therefore, the number of frequency slots needs to be sufficiently large with respect to the number of types of bandwidth.

  FIG. 7 is a schematic diagram showing an example of a procedure in which the base station 1 assigns communication lines. In the example of the procedure shown in FIG. 7, it is assumed that eight communication lines with bandwidth A, four communication lines with bandwidth B, and two communication lines with bandwidth C can be assigned to one frequency slot. . In the state shown in FIG. 7A, all frequency slots have free areas, and communication lines of any bandwidth can be allocated. In this state, the terminal station 2-1 requests the allocation of the communication line with the bandwidth A, and the line allocation control unit 11 of the base station 1 shows the state where the communication line is allocated on the system frequency band 18 as shown in FIG. Shown in The line allocation control unit 11 can allocate all the frequency slots in response to the line allocation request from the terminal station 2-1, selects the frequency slot # 1, designates it exclusively for the bandwidth A, and selects the terminal station 2- 1 communication line 21 is allocated. Next, FIG. 7C shows a state in which the terminal station 2-2 requests a communication line with the bandwidth B and the line assignment control unit 11 of the base station 1 assigns the communication line on the system frequency band 18. In response to the line allocation request from the terminal station 2-2, the line allocation control unit 11 determines that the communication slot cannot be allocated here because the frequency slot # 1 is dedicated to the bandwidth A, and designates the dedicated bandwidth. The frequency slot # 2 that has not been selected is selected, this slot is designated exclusively for the bandwidth B, and the communication line 22 for the terminal station 2-2 is allocated. Further, FIG. 7D shows a state in which the terminal station 2-3 requests a communication line with the bandwidth B and the line assignment control unit 11 of the base station 1 assigns the communication line on the system frequency band 18. In response to the line assignment request from the terminal station 2-3, the line assignment control unit 11 selects the frequency slot # 2 because the frequency slot # 2 is dedicated to the bandwidth B and has an available line capacity. To the communication line 23 for the terminal station 2-3. Further, FIG. 7E shows a state in which the terminal station 2-4 requests a communication line with the bandwidth A and the line assignment control unit 11 of the base station 1 assigns the communication line on the system frequency band 18. In response to a line assignment request from the terminal station 2-4, the line assignment control unit 11 selects the frequency slot # 1 because the frequency slot # 1 is dedicated to the bandwidth A and has an available line capacity. To the communication line 24 for the terminal station 2-4. The line information of the communication lines assigned by the line assignment control unit 11 is transmitted to each terminal station 2 via the control line 3, and communication between the base station 1 and the terminal station 2 or between the terminal stations 2 is started. To do.

  FIG. 8 is a table showing an example of a management table used by the line allocation control unit 11 of the base station 1 for communication line allocation control. As shown in FIG. 8, the line allocation management table is classified by frequency slot numbers # 1 to #N, the frequency range is described as basic information for each frequency slot number, and the bandwidth designation is specified for each frequency slot number. Entered. In the example of FIG. 8, the bandwidth specification A is input to the frequency slot # 1 and the bandwidth specification B is input to the frequency slot # 2, so as to correspond to the example of FIG. Dedicated to width A, frequency slot # 2 is dedicated to bandwidth B. A code of “undesignated” is input to the frequency slot # 3, which indicates that the frequency slot is empty. In the management table, the number of empty lines is input for each frequency slot number. In frequency slot # 1, 6 lines of bandwidth A and 2 lines of bandwidth B are input as the number of empty lines. That is, based on the size of the frequency slot (frequency bandwidth), the bandwidth designated for the frequency slot, and the number of communication lines already assigned to the frequency slot, the number of free lines that can be assigned to the frequency slot is further calculated. This can be obtained and used as management table information.

  As described above, when the line assignment control unit 11 of the base station 1 receives a line assignment request designating a bandwidth from the terminal station 2, it first manages whether there is a frequency slot designated with the same bandwidth. If a search is made from the table and there is an empty line in the corresponding frequency slot, a communication line is preferentially assigned to that frequency slot. As a result, communication lines having the same type of bandwidth are grouped in units of frequency slots. When there is no frequency slot in which the bandwidth requested by the terminal station 2 is specified, and there is no available line even if there is a frequency slot with the specified bandwidth, the line allocation control unit 11 specifies the bandwidth. An undesignated frequency slot is selected and a communication line is assigned, and a bandwidth designation and the number of free lines are input to the frequency slot. If there is no such undesignated frequency slot, a communication line having a bandwidth different from the bandwidth requested by the terminal station 2 is designated, or the terminal station 2 is notified through the control line 3 that communication cannot be performed. . Through such communication line allocation processing, the line allocation control unit 11 can more quickly allocate communication lines to free areas on the system frequency band, and can also assign communication lines for which a plurality of types of bandwidths are specified to the frequency. By specifying and assigning a dedicated bandwidth for each slot, a communication line can be assigned to an arbitrary position on the system frequency range, and the restriction on the communication line assignment processing in which multiple types of bandwidth coexist can be reduced. Can do.

  FIG. 9 is a schematic diagram showing a case where a part of the system frequency band cannot be used for some reason. In this case, a valid / invalid state is input for each frequency slot on the management table held by the line allocation control unit 11, and the frequency slot corresponding to the unusable band is excluded from communication line allocation targets. The line assignment control unit 11 can perform the same assignment process as described above for a valid frequency slot without assigning a communication line to the invalid frequency slot on the management table.

Embodiment 2

  The base station in the first embodiment performs line allocation processing for allocating a communication line to a corresponding frequency slot or the like for the bandwidth requested by the terminal station 2 in response to a line allocation request. Considering this, it is also possible to determine the bandwidth for allocating communication lines. FIG. 10 is a schematic diagram for explaining a case where communication lines are allocated with a limited bandwidth. The communication quality between the base station 1 and each terminal station 2 changes depending on the communication environment of the transmission path between them. In order for the base station 1 to perform line allocation control in consideration of the change in the communication environment, each terminal station 2 measures communication quality information (quality information such as received power and bit error) on the received control line 3. Then, the measured communication quality information is transmitted together with the communication line allocation request. When the base station 1 receives the communication line allocation request, the base station 1 acquires the communication quality information of the terminal station that has transmitted the request, and allocates the communication line according to the bandwidth request value included in the communication line allocation request if it is satisfactory. When the communication quality is deteriorated, a narrower bandwidth than the required bandwidth is allocated.

  In the illustration of FIG. 10, there is a communication obstacle between the terminal station 2-1 and the base station 1, and thus the microwave power that can be transmitted and received is reduced. When the terminal station 2-1 transmits a communication line allocation request specifying a wide bandwidth C, the base station 1 determines that communication in the bandwidths B and C is impossible, and the bandwidth A, which is a narrower bandwidth, is determined. Assign a communication line with. The frequency slot search process at the time of allocation is the same as the process described in the first embodiment. Further, regarding the terminal station 2-2, the degree of communication quality degradation is less than that of the terminal station 2-1, and the base station 1 does not allocate a wide bandwidth C, but a narrower bandwidth B (bandwidth A communication line having a width wider than A is assigned. Since the terminal station 2-3 has no deterioration in communication quality, the base station 1 assigns a communication line of the bandwidth C when the terminal station 2-3 has designated a wide bandwidth C. In addition, when the communication quality deterioration from the terminal station is severe, the base station 1 transmits information to the terminal station that the communication line cannot be allocated.

  Such communication line allocation control does not unnecessarily allocate a wide bandwidth communication line, so more efficient communication line allocation can be performed and effective use of a finite system frequency band can be achieved. Can do.

It is a block diagram of the radio | wireless communications system which concerns on Embodiment 1 of this invention. It is a block diagram of the radio | wireless communications system via the satellite which concerns on Embodiment 1 of this invention. It is a block diagram of the radio | wireless communications system via the satellite which concerns on Embodiment 1 of this invention. It is a functional block diagram of the base station which concerns on Embodiment 1 of this invention. It is a functional block diagram of a terminal station according to Embodiment 1 of the present invention. It is a schematic diagram explaining the frequency allocation in the radio | wireless communications system which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows an example of the procedure which a base station allocates a communication line. It is a table | surface which shows an example of the management table which the line allocation control part 11 of the base station 1 uses for allocation control of a communication line. It is a schematic diagram which shows the case where a part of system frequency band cannot be used for some reason. In the radio | wireless communications system which concerns on Embodiment 2 of this invention, it is a schematic diagram explaining the case where a bandwidth is restrict | limited and a communication line is allocated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base station 2 Terminal station 3 Control line 4 Communication line 11 Line allocation control part 18 System frequency band 19 Frequency slot

Claims (4)

In a wireless communication system in which communication lines are allocated between a terminal station and a base station and communication is performed between a plurality of terminal stations and the base station, the base station receives a communication line allocation request from the terminal station Then, the information of the allocated communication line is transmitted to the terminal station, the transmitter / receiver communicating with the terminal station through the communication line, the system frequency band is divided into a plurality of frequency slots, and each frequency slot has one kind of A wireless communication system, comprising: a line assignment control unit that assigns a communication line having a bandwidth and performs communication line assignment based on the communication line assignment request. A communication line allocation request from a terminal station is received, information on the allocated communication line is transmitted to the terminal station, a transceiver that communicates with the terminal station via the communication line, and a system frequency band is divided into a plurality of frequency slots. A base station comprising: a line assignment control unit that assigns a communication line of one type of bandwidth to each frequency slot and performs communication line assignment based on the communication line assignment request. In a wireless communication system in which a communication line is assigned by a base station based on a communication line assignment request from a terminal station and communication is performed between the terminal stations, the base station receives a communication line assignment request from the terminal station. A transmitter / receiver for transmitting information of the allocated communication line to the terminal station, a system frequency band is divided into a plurality of frequency slots, and a communication line of one type of bandwidth is allocated to each frequency slot, and the communication line A wireless communication system comprising: a line assignment control unit that assigns communication lines based on an assignment request. A transmitter / receiver that receives a communication line assignment request from a terminal station and transmits information on the assigned communication line to the terminal station, and a system frequency band is divided into a plurality of frequency slots, and each frequency slot has one type of band. A base station comprising: a line assignment control unit that assigns a communication line having a width and assigns a communication line based on the communication line assignment request.

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