JP2008187681A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system in which a mobile station allocates resources without requiring a complicated configuration, even when a transmissible/receivable spectrum bandwidth of a mobile station is smaller than a spectrum bandwidth transmissible/receivable for a base station. <P>SOLUTION: A base station BS determines an uplink radio resource to be allocated to a mobile station MS1 while taking into account downlink quality and the line allocation state and notifies the mobile station MS1 about a subcarrier block (frequency f+Δfi) of which the frequency is different from a frequency (f) of the radio resource just by Δfi as a downlink, and on the basis thereof, the mobile station MS1 starts reception in a resource block of frequency f+Δfi and performs transmission via the radio resource of the frequency (f). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication system such as an automobile / mobile phone system or a wireless LAN.

  In recent years, in a wireless communication system, it is expected to realize a higher-speed data communication service. The OFDM (Orthogonal Frequency Division Multiplexing) method is excellent in terms of further increasing the speed of data communication and building a flexible system (for example, see Non-Patent Document 1).

  However, on the other hand, there are mobile stations that only need to perform voice communication and short message communication in conventional services, and wireless communication systems require a wide spectrum bandwidth to achieve high-speed packet communication. Mobile stations that do not need a wide spectrum bandwidth. For this reason, the base station needs to be compatible with any mobile station, so that the spectrum bandwidth that can be transmitted / received by the mobile station differs from the spectrum bandwidth that can be transmitted / received by the base station.

As described above, when the spectrum bandwidths that can be transmitted and received are different between the mobile station and the base station, the mobile station can receive the resource control symbols in a certain reception section only in a part of the band, or at the same time, a plurality of There is a problem in that it is necessary to provide a circuit for receiving the band of the.
Takuro Sato, “From Basics to Applications of OFDM Technology,” Realize, November 30, 1999.

  In a conventional wireless communication system, the spectrum bandwidth that can be transmitted / received by the mobile station is different from the spectrum bandwidth that can be transmitted / received by the base station. However, there is a problem that it is necessary to provide a circuit for receiving a plurality of bands at the same time.

  The present invention has been made to solve the above problem, and even when the spectrum bandwidth that can be transmitted and received by the mobile station is smaller than the spectrum bandwidth that can be transmitted and received by the base station, the mobile station has a complicated configuration. An object of the present invention is to provide a wireless communication system capable of performing resource allocation without taking the measures.

  In order to achieve the above object, according to the present invention, a base station accommodated in a mobile communication network sends a base station to a mobile station to a mobile station based on quality information of a radio channel notified from the mobile station. A mobile communication system for allocating a downlink radio channel of the base station, wherein the base station determines a downlink frequency of the downlink radio channel to be allocated to the mobile station, and information indicating the downlink frequency determined by the determiner A mobile station comprising: a receiving means for receiving information transmitted by the transmitting means; and an uplink having a preset frequency difference from a downlink frequency indicated by the information received by the receiving means A transmission means for transmitting to a base station using an uplink radio channel having a frequency is provided.

  As described above, according to the present invention, when the base station notifies the mobile station of the downlink frequency, the mobile station transmits an uplink radio channel having an uplink frequency having a preset frequency difference from the downlink frequency. To transmit to the base station.

  Therefore, according to the present invention, since not only the downlink frequency but also the uplink frequency can be determined by notifying the downlink frequency, the spectrum bandwidth that can be transmitted / received by the mobile station is the spectrum bandwidth that can be transmitted / received by the base station. Even when the mobile station is smaller than the mobile station, the mobile station can provide a radio communication system capable of performing resource allocation without taking a complicated configuration.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the present invention, in order to meet the demand for further speeding up of packet transmission, OFDMA (Orthogonal Frequency Division Multiple Access) technology capable of speeding up by extending the spectrum band is applied to a cellular radio system. In this scheme, multiplex communication is realized between a plurality of mobile stations and a base station by using radio resources configured by a combination of a frequency axis and a time axis. For example, as shown in FIG. 1, when the base station BS performs one-to-one communication with a plurality of mobile stations MS1 to MS3, the base station BS allocates different radio resources to the mobile stations MS1 to MS3. One-to-one communication can be realized. In the present invention, a mobile station (hereinafter referred to as MS1) performs communication using a part of a spectrum band transmitted and received by the base station BS, and the mobile station MS1 communicates with the base station BS on a one-to-one basis. Before starting the transmission, the transmission means for notifying the base station BS of the offset value Δfi according to a predetermined procedure.

  A radio resource in OFDMA will be described with reference to FIG. The minimum unit constituting the OFDMA radio resource is an OFDM symbol set by a combination of a subcarrier frequency (fs) and a symbol time (ts). Then, as shown in FIG. 2, resource control symbols, pilot symbols, and data symbols are allocated to downlink OFDM symbols, and a radio resource is configured by a plurality of OFDM symbols. The resource control symbol indicates information related to radio resources that the base station BS allocates in a certain reception unit (Trx).

  In addition, the arrangement of pilot symbols in radio resources and the arrangement of resource control symbols in a certain reception unit are determined in advance by the radio system so as to satisfy predetermined reception performance, and are limited to the arrangement illustrated in FIG. It is not something that can be done.

  FIG. 3 shows the configuration of the base station BS of the wireless communication system according to the embodiment of the present invention. This base station BS includes data bit generators 1011 to 101n, encoders 1021 to 102n, modulators 1031 to 103n, pilot symbol generator 1040, OFDM symbol mapping unit 1050, DA converter 1060, transmission RF Processing unit 1070, reception RF processing unit 1080, AD converter 1090, OFDM symbol demapping unit 1100, downlink quality information detection units 1111 to 111n, data bit recovery units 1121 to 112n, and uplink quality detection Unit 1130, control unit 1140, and resource control symbol generation unit 1150.

Data bit generation units 1011 to 101n generate data bits of communication data to be transmitted to mobile stations MS1 to MSn, respectively.
The encoders 1021 to 102n correspond to the data bit generation units 1011 to 101n, respectively, encode the generated data bits, and obtain encoded data.
Modulators 1031 to 103n correspond to encoders 1021 to 102n, respectively, and obtain data symbols obtained by mapping the obtained encoded data on the I and Q axes of the orthogonal coordinate plane.
Pilot symbol generation section 1040 generates pilot symbols.

  For each mobile station MS1 to MSn, OFDM symbol mapping section 1050 receives the data symbol, the pilot symbol, and a resource control symbol generated by resource control symbol generation section 1150, which will be described later, and inputs these symbols. In accordance with an instruction from the control unit 1140, which will be described later, an OFDM symbol (digital signal) is obtained by mapping to resource blocks associated with the mobile stations MS1 to MSn.

The DA converter 1060 performs digital / analog conversion on the digital signal output from the OFDM symbol mapping unit 1050.
The transmission RF processing unit 1070 converts the analog signal obtained by the DA converter 1060 into a predetermined radio frequency and wirelessly transmits it through the antenna.

The reception RF processing unit 1080 receives radio signals transmitted in a predetermined radio frequency band from the mobile stations MS1 to MSn, and frequency-converts them into baseband signal.
The AD converter 1090 converts the baseband signal output from the reception RF processing unit 1080 into a digital signal using an internally generated clock to obtain an OFDM symbol.
The OFDM symbol demapping unit 1100 demaps the OFDM symbol output from the AD converter 1090.

  Downlink quality information detecting sections 1111 to 111n receive radio resource control symbols associated in advance among the OFDM symbols demapped by OFDM symbol demapping section 1100, and demodulate and decode the control symbols. Thus, downlink quality information transmitted from each of the mobile stations MS1 to MSn is detected through the radio resource. Further, when the downlink quality information detecting units 1111 to 111n are able to detect the downlink quality information, the downlink quality information detecting units 1111 to 111n are regarded as those transmitted from the mobile stations MS1 to MSn to which the corresponding radio resources are allocated, respectively. This is notified to the control unit 1140.

  Data bit reproduction sections 1121 to 112n demodulate and decode data symbols of radio resources associated in advance among the demapped OFDM symbols, respectively, and receive data bits transmitted from mobile stations MS1 to MSn, respectively. Reproduce. Data bit recovery sections 1121 to 112n detect errors occurring in received symbols in data bit recovery, and notify uplink quality detection section 1130 of the errors.

  Uplink quality detection section 1130 can receive at the base station BS including the uplink of each of mobile stations MS1 to MSn based on the error occurrence status of the received symbols notified from data bit recovery sections 1121 to 112n. Uplink quality information in all bands is detected and notified to the control unit 1140.

  The control unit 1140 includes a CPU (Central Processing Unit) and a storage unit that stores control data and control programs, resource blocks allocated to the mobile stations MS1 to MSn, and allocation information indicating available resource blocks. It operates according to the control data and control program.

  The control unit 1140 stores the downlink quality information detected by the downlink quality information detection units 1111 to 111n, the quality information of each uplink detected by the uplink quality detection unit 1130, and the storage unit at this time. Based on the allocation information, uplink radio resources and downlink resource blocks to be allocated to the mobile stations MS1 to MSn are determined.

  When the uplink radio resource for the mobile station MS1 is changed, the control unit 1140 determines the frequency (f + Δfi) of the resource block to be allocated to the mobile station for reception, based on the updated frequency f of the uplink radio resource. Control is performed to notify the mobile station MS1 as the designation information.

In addition, when the radio resource assigned to the mobile station MS1 is changed, the control unit 1140 confirms that the uplink signal is received through the newly assigned resource block (frequency f + Δfi) and the radio resource having the frequency f of the frequency difference Δfi. By calculating the subcarrier number of the OFDM symbol corresponding to the downlink frequency f + Δfi, controlling the OFDM symbol mapping unit 1050 and processing so that the data symbol of the mobile station MS1 is mapped on the subcarrier number, Transmission through the resource block (frequency f + Δfi) is started.
If the radio resource allocated to the mobile station is changed by the above processing, the allocation information stored in the storage unit is updated accordingly.

  Resource control symbol generation section 1150 generates a resource control symbol based on resource control information indicating the subcarrier number obtained by control section 1140.

  FIG. 4 shows the configuration of mobile stations MS1 to MSn in the wireless communication system according to the embodiment of the present invention. The mobile stations MS1 to MSn include a reception RF processing unit 2010, a local signal generation unit 2020, an AD converter 2030, an OFDM symbol demapping unit 2040, a resource control information extraction unit 2050, a demodulation unit 2060, and a decoder 2070. A data bit reproduction unit 2080, a downlink quality detection unit 2090, a downlink quality information generation unit 2100, an encoder 2110, a modulation unit 2120, a data bit generation unit 2130, an encoder 2140, and a modulation unit 2150. OFDM symbol mapping section 2160, DA converter 2170, and transmission RF processing section 2180.

  The reception RF processing unit 2010 receives the RF signal transmitted from the base station BS described above, and frequency-converts the RF signal into a baseband signal in the baseband band using the reception local signal generated by the local signal generation unit 2020 described later.

  The local signal generation unit 2020 receives a reception local signal having a frequency according to an instruction from a resource control information extraction unit 2050 described later, and the reception local signal and a transmission local signal having a preset frequency difference Δfi. Generate.

The AD converter 2030 reproduces a clock based on the baseband signal, and converts the baseband signal into a digital signal using the clock.
The OFDM symbol demapping unit 2040 performs demapping on the digital signal (OFDM symbol), and extracts pilot symbols, resource control symbols, and data symbols belonging to the resource control symbols.

  The resource control information extraction unit 2050 decodes the resource control symbol by a preset method, extracts resource control information for identifying the data symbol addressed to the mobile station from the data symbols, and demodulates based on the resource control information The unit 2060 is instructed on the data symbol to be demodulated.

  In addition, when the resource control information includes specification information that specifies the updated frequency f + Δfi of the resource block to be received by the mobile station, the resource control information extraction unit 2050 uses the frequency specified by the specification information. The frequency of the reception local signal generated by the local signal generation unit 2020 is controlled so as to receive f + Δfi. Note that, when the frequency of the reception local signal is controlled, the local signal generation unit 2020 generates a transmission local signal having a frequency difference Δfi with the frequency of the reception local signal.

Demodulation section 2060 demodulates the data symbol addressed to the mobile station indicated by resource control information extraction section 2050 among the data symbols obtained by OFDM symbol demapping section 2040 to obtain encoded data.
The decoder 2070 decodes the encoded data output from the demodulation unit 2060.
Data bit reproduction unit 2080 reproduces communication data and control information from the encoded data decoded by decoder 2070.

Downlink quality detection section 2090 measures the reception quality (interference level, etc.) of the resource block allocated to the mobile station, based on the pilot symbol obtained by OFDM symbol demapping section 2040.
The downlink quality information generation unit 2100 generates downlink quality information for notifying the base station BS of the reception quality result measured by the downlink quality detection unit 2090.

The encoder 2110 obtains encoded data obtained by encoding the downlink quality information generated by the downlink quality information generation unit 2100.
Modulation section 2120 obtains data symbols obtained by mapping the encoded data obtained by encoder 2110 as I and Q symbols on the orthogonal coordinate plane.

The data bit generation unit 2130 generates data bits of communication data and control information to be transmitted to the base station BS.
The encoder 2140 obtains encoded data obtained by encoding the downlink quality information generated by the data bit generation unit 2130.
Modulation section 2150 obtains data symbols obtained by mapping the encoded data obtained by encoder 2140 as I and Q symbols on the orthogonal coordinate plane.

  The OFDM symbol mapping unit 2160 maps the data symbols obtained by the modulation units 2120 and 2150 to OFDM symbols to obtain OFDM symbols (digital signals).

The DA converter 2170 performs digital / analog conversion on the digital signal output from the OFDM symbol mapping unit 2160.
The transmission RF processing unit 2180 converts the analog signal obtained by the DA converter 2170 into a radio frequency in a band designated by the base station BS using the transmission local signal generated by the local signal generation unit 2020. And wirelessly transmit through the antenna.

  Next, an operation of assigning radio resources in the radio communication system configured as described above will be described. FIG. 5 is a flowchart for explaining radio resource allocation control by the base station BS. The processing shown in this flowchart is performed by the control unit 1140, and is executed when it becomes necessary to allocate radio resources to the mobile station. In the following description, a case where the base station BS assigns to the mobile station MS1 will be described as an example.

First, in step 5a, the control unit 1140 acquires the downlink quality information detected by the downlink quality information detection units 1111 to 111n, respectively, and proceeds to step 5b.
In step 5b, the control unit 1140 acquires the quality information of each uplink detected by the uplink quality detection unit 1130, and proceeds to step 5c.
In step 5c, the control unit 1140 reads the allocation information stored in the storage unit at this time, and proceeds to step 5d.

  In step 5d, the control unit 1140 detects a plurality of frequency bands (f) having a low usage rate and a low interference other than the mobile station to be allocated in the uplink, based on the uplink quality information and the allocation information, Then, a frequency band having good quality information on the downlink of the frequency f + Δfi based on the frequency f is determined as a radio resource, and the process proceeds to step 5e.

  In step 5e, the control unit 1140 determines the frequency f + Δfi of the resource block to be allocated to the mobile station MS1 for reception (downlink) based on the frequency f of the radio resource determined in step 5d, and the subcarrier corresponding to this frequency Ask for a number. Then, the control unit 1140 notifies the resource control symbol generation unit 1150 of the frequency f + Δfi of the resource block, and generates a resource control symbol including designation information indicating the frequency f + Δfi. Further, the control unit 1140 controls the OFDM symbol mapping unit 1050 to transmit the resource control symbol to the mobile station MS1, and proceeds to Step 5f.

  On the other hand, in the mobile station MS1 that has received the resource control symbol including the designation information, the resource control information extraction unit 2050 detects the designation information by decoding the resource control symbol and is designated by the designation information. The frequency of the reception local signal generated by the local signal generation unit 2020 is controlled so as to receive the frequency f + Δfi, and the transmission local signal having a frequency difference Δfi with the frequency of the reception local signal is controlled. . Thus, transmission data such as downlink quality is transmitted from the mobile station MS1 to the base station BS through the radio resource of the frequency f.

  In step 5f, when the control unit 1140 detects the downlink quality information of the mobile station MS1 from the OFDM symbol corresponding to the frequency f among the downlink quality information detection units 1111 to 111n, the mobile station MS1 transmits in step 5e. Assuming that the received resource control information has been received, the process proceeds to step 5g. If the one corresponding to the frequency f does not detect downlink quality information, reception is continuously monitored in step 5f.

  In step 5g, the control unit 1140 maps the data symbol addressed to the mobile station MS1 and the resource control symbol to the OFDM symbol having the subcarrier number corresponding to the resource block of frequency f + Δfi, to the OFDM symbol mapping unit 1050. The process proceeds to step 5h. Thereby, OFDM symbol mapping section 1050 assigns the downlink signal addressed to mobile station MS1 to the resource block of frequency f + Δfi and performs transmission.

  In step 5h, the control unit 1140 updates the resource block having the frequency f + Δfi among the allocation information stored in the storage unit to information indicating that it has been allocated, and ends the process.

  As described above, in the radio communication system configured as described above, the base station BS determines uplink radio resources to be allocated to the mobile station MS1 in consideration of uplink quality, downlink quality, and channel allocation status, and this radio The mobile station MS1 is notified of a subcarrier block (frequency f + Δfi) whose frequency is different from the resource frequency f by Δfi as a downlink, and based on this, the mobile station MS1 starts reception with the resource block of the frequency f + Δfi, and the frequency Transmission is performed through the radio resource f.

That is, as shown in FIG. 6, when the frequency f _rx1 is assigned as the downlink, the mobile station MS1 sets the frequency f _tx1 different from this by Δfi as the uplink frequency, and then _{sets the} frequency f _rx2 as the downlink. Is assigned, the frequency f _tx2 , which is different from this by Δfi, is used as the uplink frequency.

  Therefore, according to the radio communication system having the above configuration, the base station BS can notify the mobile station MS1 of the frequency f + Δfi of the resource block used for the downlink, and can notify that the frequency f is used for the uplink.

  For this reason, even if the spectrum bandwidth that can be transmitted / received by the mobile station MS1 is smaller than the spectrum bandwidth that is transmitted / received by the base station BS, the mobile station MS1 can determine the frequency of the local signal for transmission and the local signal for reception. It is only necessary to control the frequencies collectively in conjunction with each other, and a complicated configuration such as independent control is unnecessary, and resource allocation can be performed with a simple configuration.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. Further, for example, a configuration in which some components are deleted from all the components shown in the embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

  As an example, for example, in the above embodiment, the base station BS determines uplink radio resources to be allocated to the mobile station MS1 in consideration of uplink quality, downlink quality and channel allocation status. It is not always necessary to consider all of the uplink quality, downlink quality, and channel allocation status.

Further, in the above embodiment, the downlink quality is taken into consideration before the channel allocation, but after the channel allocation, the downlink quality is reported to the mobile station, and the mobile station is based on this report. Then, the line assignment may be reviewed.
In addition, it goes without saying that the present invention can be similarly implemented even if various modifications are made without departing from the gist of the present invention.

The figure which showed typically the radio | wireless communications system concerning this invention. The figure for demonstrating the structure of the radio | wireless resource used with the radio | wireless communications system shown in FIG. The circuit block diagram which shows the structure of the base station of the radio | wireless communications system shown in FIG. FIG. 2 is a circuit block diagram showing a configuration of a mobile station in the wireless communication system shown in FIG. 1. FIG. 4 is a flowchart for explaining radio resource allocation operation of the base station shown in FIG. 3. FIG. The figure for demonstrating the radio | wireless resource allocated to a mobile station by the process shown in FIG.

Explanation of symbols

  1011 to 101n: Data bit generation unit, 1021 to 102n ... Encoder, 1031 to 103n ... Modulation unit, 1040 ... Pilot symbol generation unit, 1050 ... OFDM symbol mapping unit, 1060 ... DA converter, 1070 ... Transmission RF processing unit, 1080 ... Reception RF processing unit, 1090... AD converter, 1100. , 1150 ... Resource control symbol generator, 2010 ... Reception RF processor, 2020 ... Local signal generator, 2030 ... AD converter, 2040 ... OFDM symbol demapping unit, 2050 ... Resource control information extractor, 2060 ... Demodulator , 2070 ... decoder, 2080 ... Data bit reproduction unit, 2090 ... Downlink quality detection unit, 2100 ... Downlink quality information generation unit, 2110 ... Encoder, 2120 ... Modulation unit, 2130 ... Data bit generation unit, 2140 ... Encoder, 2150 ... Modulation unit, 2160 ... OFDM symbol Mapping unit, 2170 ... DA converter, 2180 ... transmission RF processing unit, BS ... base station, MS1 to MSn ... mobile station.

Claims (5)

A mobile communication system in which a base station accommodated in a mobile communication network assigns a downlink radio channel from a base station to a mobile station to the mobile station based on radio channel quality information notified from the mobile station There,
The base station
Determining means for determining a downlink frequency of a downlink radio link assigned to the mobile station;
Transmission means for wirelessly transmitting information indicating the downlink frequency determined by the determination means,
The mobile station performs transmission and reception by partially using a frequency band transmitted and received by the base station,
Receiving means for receiving information transmitted by the transmitting means;
Transmission means for transmitting to the base station using an uplink radio channel having an uplink frequency having a preset frequency difference from the downlink frequency indicated by the information received by the reception means, Mobile communication system. A mobile communication system in which a base station accommodated in a mobile communication network assigns a downlink radio channel from a base station to a mobile station to the mobile station based on radio channel quality information notified from the mobile station There,
The base station
Detection means for detecting uplink quality from the mobile station to the base station based on a signal received from the mobile station;
First determining means for determining an uplink frequency of an uplink to be allocated to the mobile station based on the uplink quality detected by the detecting means;
Second determining means for determining a frequency having a preset frequency difference from an uplink frequency determined by the determining means as a downlink frequency of a downlink radio link to be assigned to the mobile station;
Transmission means for wirelessly transmitting information indicating the downlink frequency determined by the second determination means,
The mobile station
Receiving means for receiving information transmitted by the transmitting means;
Transmission means for performing transmission addressed to the base station using the uplink radio channel having the uplink frequency having the frequency difference from the downlink frequency indicated by the information received by the reception means. Mobile communication system. The base station further comprises receiving means for receiving a radio signal from the mobile station through an uplink radio channel of the uplink frequency,
The transmitting means, when the receiving means receives a radio signal from the mobile station via the uplink radio channel of the uplink frequency, performs radio transmission addressed to the mobile station via the downlink radio channel of the downlink frequency. The mobile communication system according to claim 1 or 2, wherein the mobile communication system is started. The base station further comprises line status detection means for detecting a usage status of a radio line used in radio communication with the mobile station,
The first determining means determines an uplink frequency of an uplink to be allocated to the mobile station based on a detection result of the line condition detecting means and an uplink quality detected by the detecting means. The mobile communication system according to claim 2.   The mobile communication system according to claim 2, wherein the detection means detects each quality of the uplink and the downlink based on a signal received from the mobile station.

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