JP2005065101A - Wireless communication apparatus and wireless communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the collapse of orthogonality of spreading codes even when the same frequency band is used by adopting a common TDD-CDMA system for communication in an ad hoc network and a mobile communication network, and an ad hoc network Provided is a wireless communication apparatus capable of reducing mutual interference of a mobile communication network.
A radio communication apparatus 10 uses a TDD-CDMA system for communication with a base station 30 of a mobile communication network. An ad hoc communication unit is provided that constructs an ad hoc network with other wireless communication devices 10 and 20 existing in the vicinity and performs wireless communication with the other wireless communication devices. This ad hoc communication means adopts the same frequency band by adopting the TDD-CDMA method common to the mobile communication network when communicating with the other wireless communication device, and synchronizes with the communication in the mobile communication network. To communicate with the other wireless communication device.
[Selection] Figure 2

Description

  The present invention relates to a TDD-CDMA wireless communication apparatus and a wireless communication method using the same.

  As is well known, in a mobile communication network, mobile stations are configured by wireless communication devices (User Equipment) such as mobile phones, personal computers, and PDAs, and data transmission between these mobile stations and base stations is performed wirelessly. It has become. Further, when performing a voice call or data communication between mobile stations, data is exchanged via a base station (Base Station) as shown in FIG. As communication systems used for such mobile communication, for example, GSM (Global System for Mobile Communications), WCDMA (Wideband Code Division Multiple Access), and the like are known.

  In the mobile communication network, the communication between the mobile station and the base station is bidirectional, and the communication method is a reciprocation method in which transmission and reception are performed simultaneously. As shown in FIG. 7, the recovery scheme includes FDD (Frequency Division Duplex) that uses different frequency bands for the uplink (Uplink) from the mobile station to the base station and the downlink (Downlink) from the base station to the mobile station. ) Method and the TDD (Time Division Duplex) method in which the uplink and downlink frequency bands are the same, but the upper and lower lines are switched in a very short time. In the TDD system, one frame is divided into a plurality of (for example, 15) time slots, and either uplink or downlink is assigned to each of the time slots. FIG. 8 shows a frame configuration of TDD-CDMA (Code Division Multiple Access) adopting this TDD scheme as a recovery scheme. In this TDD-CDMA scheme, the ratio and arrangement of time slots allocated to the uplink and downlink. Can be appropriately set according to the traffic volume and the like.

  On the other hand, an ad hoc network is known as a wireless short-range data communication network. In this ad hoc network, as shown in FIG. 9, it is possible to perform direct communication between wireless communication devices within the reach of radio waves without intervening base stations. Therefore, according to the ad hoc network, there is no need for a base station or an access point, and there is an advantage that a network can be easily constructed even in a place without such communication facilities. As communication technologies for constructing such an ad hoc network, for example, Bluetooth and wireless LAN (IEEE802.11x) have been proposed.

However, in the past, since different communication methods have been adopted for the ad hoc network and the mobile communication network, when trying to realize a wireless communication device that can be connected to both the networks, the configuration of the wireless communication device is naturally complicated. Therefore, there is a problem that the cost increases correspondingly.
In addition, when switching the connection destination from one network (for example, an ad hoc network) to the other network (for example, a mobile communication network), since both communication methods are different, it takes time for handover. There was also.

  Accordingly, the present inventors have previously used the same frequency band by adopting a common TDD-CDMA system for communication in an ad hoc network and communication in a mobile communication network as a wireless communication apparatus that solves the above-described problems. We are developing wireless communication devices. According to this wireless communication apparatus, since the communication methods in the ad hoc network and the mobile communication network are unified, it is possible to avoid complication of the apparatus configuration and an increase in cost, and to smoothly switch the connected network. The advantage that it can be obtained.

  However, in the above wireless communication device, for example, if communication is performed independently in a mobile communication network and an ad hoc network, the same frequency band is used in both networks. This causes a problem of interference. That is, in the TDD-CDMA system, signals are prevented from interfering with each other by using orthogonal spreading codes. However, if the synchronization is insufficient, the orthogonality is lost and interference occurs.

  The present invention has been made in view of such circumstances, and even when the same frequency band is used by adopting a common TDD-CDMA system for communication in an ad hoc network and a mobile communication network, the orthogonality of spreading codes is improved. It is an object of the present invention to provide a wireless communication apparatus that can avoid collapse and thereby reduce mutual interference between an ad hoc network and a mobile communication network.

  The invention according to claim 1 is a wireless communication apparatus that uses the TDD-CDMA system for communication with a base station of a mobile communication network, and constructs an ad hoc network with other wireless communication apparatuses existing in the surrounding area. Ad hoc communication means for wirelessly communicating with another wireless communication apparatus, and the ad hoc communication means adopts a TDD-CDMA system common to the mobile communication network when communicating with the other wireless communication apparatus. The same frequency band is used, and communication with the other wireless communication device is performed in synchronization with the communication in the mobile communication network.

Here, TDD-CDMA is CDMA that uses the TDD scheme as a recovery scheme. CDMA is one of multiple access systems applying a spread spectrum system, and is a communication system called code division multiple access. Examples of TDD-CDMA include TD-CDMA standardized by 3GPP (3rd Generation Partnership Project).
Examples of the “wireless communication apparatus that uses the TDD-CDMA system for communication with a base station of a mobile communication network” include, for example, a mobile phone, a PDA (Personal Digital Assistance) or a personal computer having a connection function with the mobile communication network Information terminal etc. are mentioned.

  In addition, the “other wireless communication devices existing around” do not have, for example, a connection function with the mobile communication network in addition to the wireless communication device with the connection function with the mobile communication network as described above. Information terminals (computer, PDA, etc.), peripheral devices of information terminals (eg, headset, printer, mouse, display), etc. are also included. These wireless communication devices construct an ad hoc network with at least other wireless communication devices within the radio wave reach, and communicate with each other within the ad hoc network (hereinafter referred to as an ad hoc communication function). It has a name.)

  According to a second aspect of the present invention, in the wireless communication device according to the first aspect, the ad hoc communication means detects surrounding wireless communication devices that can construct the ad hoc network, and stores information about the wireless communication devices, respectively. After executing the processing acquired from the storage unit and stored in the storage unit, information on the wireless communication device that is a communication partner is extracted from the information stored in the storage unit, and the communication partner is based on the information The wireless communication apparatus and the ad hoc network communicate with each other.

  Here, the information regarding the wireless communication device includes, for example, a spreading code used by each wireless communication device at the time of transmission, an identification code (ID) of each wireless communication device, and attribute information of each wireless communication device (device type, performance, Security level, etc.), information on the communication path to each wireless communication device, and the like.

  According to a third aspect of the present invention, in the wireless communication device according to the first or second aspect, the ad hoc communication means performs communication in the mobile communication network based on synchronization information received from the base station. It is characterized by synchronization.

  According to a fourth aspect of the present invention, there is provided a wireless communication method in which an ad hoc network is constructed by a plurality of wireless communication devices including the wireless communication device according to any one of the first to third aspects, and communication within the ad hoc network is performed. Adopting a TDD-CDMA system common to communication in a mobile communication network, using the same frequency band, and performing communication in the ad hoc network in synchronization with communication in the mobile communication network To do.

  Here, in addition to the wireless communication device according to any one of claims 1 to 3, the plurality of wireless communication devices do not have a connection function with a mobile communication network but have an ad hoc communication function. Is also included.

  According to the invention according to any one of claims 1 to 4, since the same frequency band is used by adopting a common TDD-CDMA system for communication in the ad hoc network and the mobile communication network, A wireless communication apparatus that can be connected to both mobile communication networks can be provided at a low cost with a simple configuration. In addition, since communication is performed in each network with synchronization established between the ad hoc network and the mobile communication network, even when the same frequency band is used in the ad hoc network and the mobile communication network, the spreading code is used. Can be avoided. Therefore, mutual interference between the ad hoc network and the mobile communication network can be reduced, and a good communication state can be ensured in any of the networks.

  As described above, according to the present invention, it is possible to provide a wireless communication apparatus that can be connected to both an ad hoc network and a mobile communication network at a low cost with a simple configuration. Further, even if the same frequency band is used for the ad hoc network and the mobile communication network, the orthogonality of the spreading codes can be maintained, and the mutual interference between the ad hoc network and the mobile communication network can be reduced. Therefore, a good communication state can be ensured regardless of which network is used.

FIG. 1 shows an embodiment of an ad hoc network to which a wireless communication method according to the present invention is applied. In FIG. 1, reference numeral 10 denotes a first wireless communication apparatus, and reference numeral 20 denotes a second wireless communication apparatus.
The first wireless communication device 10 is a wireless communication device (wireless communication device according to the present invention) having a connection function with a mobile communication network, and is composed of, for example, a mobile phone, a PDA, a personal computer, or the like. The first wireless communication apparatus 10 uses a TDD-CDMA system for communication with the base station 30 of the mobile communication network.
On the other hand, the second wireless communication device 20 is a wireless communication device that does not have a connection function with a mobile communication network, and is information connected to a fixed communication network such as a LAN (Local Area Network) by wire or wireless. The terminal is composed of a terminal (for example, a personal computer, a workstation, etc.) and peripheral devices (for example, a headset, a printer, a mouse) of the information terminal.

  These first and second wireless communication devices 10 and 20 form an ad hoc network with other wireless communication devices 10 and 20 existing in the vicinity, and communicate with each other between the wireless communication devices in the ad hoc network. It has a communication function, and adopts the same frequency band by adopting the TDD-CDMA method common to the communication method in the mobile communication network. In the communication, as shown in FIG. 2, the communication in the ad hoc network is performed in synchronization with the communication in the mobile communication network.

  FIG. 3 is a block diagram showing a main configuration of the first wireless communication apparatus. As shown in FIG. 3, the first wireless communication device 10 includes a transmitter 11, a receiver 12, an antenna 13, a control unit 14, and a storage unit 15.

  The transmitter 11 includes a transmission data processing unit 11a that generates a transmission signal, a primary modulation unit 11b that primarily modulates a carrier wave with the transmission signal, and a modulation signal obtained by the primary modulation using a spreading code (orthogonal spreading code). A diffusion unit 11c that performs (secondary modulation) and an amplification unit 11d that amplifies the diffusion-modulated signal are provided. That is, the transmission signal generated by the transmission data processing unit 11a is primarily modulated by the primary modulation unit 11b using a predetermined modulation method, then spread-modulated by the spreading code by the spreading unit 11c, and then transmitted to the amplification unit 11d. It is amplified and radiated as radio waves from the antenna 13. Note that the spreading code uses a code with high orthogonality in which the cross-correlation between codes is sufficiently small when there is no phase difference between the codes.

  On the other hand, the receiver 12 includes a band filter 12a that removes unnecessary noise components included in the received signal received from the antenna 13, and a despreading unit 12b that despreads the received signal that has passed through the band filter 12a with a spreading code. A demodulation unit 12c that demodulates a signal obtained by despreading, and a reception data processing unit 12d that performs various processes related to connection to an ad hoc network or a mobile communication network based on the demodulated signal. That is, the received signal received by the antenna 13 is despread by the same spreading code as that on the transmission side after the noise component is removed by the band filter 12a, and then demodulated by the demodulator 12c to return to the baseband waveform. It is supposed to be.

  The control unit 14 controls the transmitter 11 and the receiver 12 based on various types of information stored in the storage unit 15, and the control unit 14 controls synchronization between the ad hoc network and the mobile communication network (synchronization). Acquisition, synchronization holding), transmission / reception switching control, transmission power output control (power control), switching control between an ad hoc network and a mobile communication network, and the like. For example, when communicating with a base station 30 of a mobile communication network or another wireless communication device in an ad hoc network using a wireless line, switching between transmission and reception is performed based on a preset time slot assignment. The communication is performed by the TDD method. Further, when communicating with other wireless communication devices in the ad hoc network, the other communication devices in the ad hoc network are matched with the communication timing in the mobile communication network based on the synchronization information received from the base station 30. The communication timing with the wireless communication apparatus is set. Further, when communicating with other wireless communication devices in the ad hoc network, the interference level is detected from the received signal input to the receiver 12, and the transmission power is adjusted according to the interference level. Yes.

In this embodiment, the transmitter 11, the receiver 12, the antenna 13, the control unit 14, the storage unit 15 and the like constitute an ad hoc communication unit according to the present invention.
On the other hand, the second wireless communication device 20 also has the same transmitter, receiver, antenna, control unit, and storage unit as those of the first wireless communication device 10, and other wireless devices in the ad hoc network are provided by these communication means. It is possible to communicate with a communication apparatus using a wireless line without the intervention of the base station 30.

Next, connection processing to the ad hoc network executed by the first wireless communication apparatus 10 having the above configuration will be described based on the flowchart of FIG.
First, in step S1, processing for switching the communication mode to the ad hoc mode is performed. This process may be performed automatically when a preset condition is satisfied, or may be performed based on a user's input operation.

  Next, in step S <b> 2, processing for acquiring information related to the wireless communication devices 10 and 20 existing around is performed. Specifically, based on the received signal input to the receiver 12, it is investigated whether or not the wireless communication devices 10 and 20 in the ad hoc mode exist in the vicinity, and as a result, other wireless devices in the ad hoc mode If the communication devices 10 and 20 exist in the vicinity, whether or not each of the wireless communication devices 10 and 20 has an authority to connect to the ad hoc network, and whether or not it is connectable to the ad hoc network Each of the wireless communication devices 10 and 20 in the ad hoc mode is identified and detected from the wireless communication devices 10 and 20 in the ad hoc mode. After that, information related to the wireless communication devices (for example, spreading codes used at the time of transmission, device-specific IDs, etc.) is stored in the storage means such as the storage unit 15, and then the process proceeds to the next step S3.

  In step S3, a process of selecting a time slot to be used for communication within the ad hoc network from TDD-CDMA time slots is performed. Selection methods include: (1) selecting only the time slot specified for downlink (Downlink), (2) selecting only the time slot specified for uplink (Uplink), (3) uplink The time slot specified in (1) and the time slot specified in the downlink are listed, but any method may be adopted. In this embodiment, in order to reduce mutual interference between the ad hoc network and the mobile communication network, only the time slot designated for the downlink is selected.

  In step S4, a signal from the base station 30 is received, information for synchronization included in a predetermined time slot of the received signal is extracted, and communication timing in the mobile communication network is determined based on the information for synchronization. Processing for setting the communication timing in the ad hoc network is performed so as to match.

  In step S5, information related to the wireless communication device (the first wireless communication device 10 or the second wireless communication device 20) as a communication partner is extracted from the information stored in the storage unit, and based on the information, Communication is performed with a wireless communication device as a communication partner via an ad hoc network. In that case, power control is performed so as not to interfere with nearby wireless communication apparatuses not participating in the ad hoc network. That is, the interference level of all time slots is measured based on the received signal input to the receiver 12, and the sum of the measured value and a preset offset value (positive or negative) is the maximum value of the transmission power. As the (allowable value), transmission power output control is performed so as not to exceed this maximum value.

  Then, after the connection to the ad hoc network is completed, the state of the ad hoc network is monitored in the same manner as in step S2 described above until the number of wireless communication devices 10 and 20 constituting the ad hoc network reaches an upper limit (for example, 15). The processing is repeated at a predetermined cycle, and information regarding the wireless communication devices 10 and 20 included in the ad hoc network is updated as appropriate (step S6). Further, when the number of wireless communication devices constituting the ad hoc network becomes “1”, the ad hoc network automatically disappears.

Next, a method for synchronizing the ad hoc network and the mobile communication network will be specifically described.
First, all base stations 30 constituting a mobile communication network communicate with each other via a wired network, or by using GPS (Global Positioning System) or DGPS (Differential GPS). Take time synchronization of the entire communication network.

  Next, each base station 30 inserts synchronization information into a predetermined time slot set in advance in a TDD-CDMA time slot, and transmits a signal including the information so as to reach the entire cell. As shown in FIG. 5, the TDD-CDMA time slot is composed of 15 time slots, and 1 time slot is composed of 2560 chips. Each time slot is assigned either an uplink or a downlink.

  Next, the radio communication apparatuses 10 and 20 in the cell receive the signal from the base station 30, extract the synchronization information included in the predetermined time slot of the received signal, and based on the synchronization information Thus, processing for setting the communication timing in the ad hoc network so as to match the communication timing in the mobile communication network at the chip level (the processing in step S4 described above) is performed. Specifically, examples of a method for obtaining synchronization based on the information for synchronization include a method using a sliding correlator and a method using a matched filter, and any method may be adopted. For example, in a method using a sliding correlator, a known code sequence (eg, Gold code) between the base station 30 and the wireless communication apparatus is used as the synchronization information. In this method, the phase of the code sequence is changed little by little at the wireless communication device (reception side), and this is sequentially compared with the code sequence received from the base station 30 (transmission side), and the autocorrelation peak appears in the output. By detecting this, chip level synchronization acquisition is performed, and by detecting a plurality of pieces of information of the peak, slot and frame level synchronization acquisition is performed. Through the above processing, synchronization between the ad hoc network and the mobile communication network is established.

  As described above, according to the present embodiment, the same frequency band is used by adopting the common TDD-CDMA system for communication in the ad hoc network and the mobile communication network, so the ad hoc network and the mobile communication network are used. It is possible to provide the wireless communication device 10 that can be connected to both of them at a low cost with a simple configuration.

  In addition, since communication is performed in each network with synchronization established between the ad hoc network and the mobile communication network, even if the same frequency band is used in the ad hoc network and the mobile communication network, the spread code Can be avoided, and an increase in cross-correlation between spreading codes due to a phase difference can be prevented. Therefore, mutual interference between the ad hoc network and the mobile communication network can be reduced, and a good communication state can be ensured in any of the networks.

  In addition, since the wireless communication devices 10 and 20 in the ad hoc network communicate with each other, it is possible to reduce the load on the mobile communication network, thereby improving the communication efficiency of the entire network. In addition, the communication capacity of the network can be increased.

  Furthermore, when the radio wave does not reach the base station 30, the other radio communication devices 10 and 20 in the ad hoc network that reach the base station 30 can be used as relay devices, and the mobile communication network As a result, the connectable area can be expanded. In addition, since a common TDD-CDMA system is used for communication in an ad hoc network and a mobile communication network, handover between both networks can be smoothly executed.

It is a schematic block diagram which shows one Embodiment of the ad hoc network to which the radio | wireless communication method which concerns on this invention is applied. It is a figure which shows the state which is synchronizing and performing communication between an ad hoc network and a mobile communication network. It is a block diagram which shows the principal part structure of the 1st radio | wireless communication apparatus of FIG. It is a flowchart for demonstrating the connection process to the ad hoc network of FIG. It is a figure which shows the structure of the time slot of TDD-CDMA. It is a schematic block diagram which shows an example of a mobile communication network. It is a schematic diagram for demonstrating a TDD system and a FDD system. It is a figure which shows an example of the frame structure of TDD-CDMA. It is a schematic block diagram which shows an example of an ad hoc network.

Explanation of symbols

10 First wireless communication device 20 Second wireless communication device 30 Base station

Claims (4)

A wireless communication apparatus using a TDD-CDMA system for communication with a base station of a mobile communication network,
An ad hoc communication unit that constructs an ad hoc network with other wireless communication devices existing in the vicinity and communicates with the other wireless communication device wirelessly is provided, and the ad hoc communication unit is configured to communicate with the other wireless communication device. Adopting a TDD-CDMA system common to the mobile communication network, using the same frequency band, and communicating with the other wireless communication apparatus in synchronization with the communication in the mobile communication network A wireless communication device characterized in that   The ad hoc communication means detects surrounding wireless communication devices that can construct the ad hoc network, performs processing for acquiring information about the wireless communication devices from each of them and storing the information in the storage means, and then storing the information in the storage means Information related to a wireless communication device as a communication partner is extracted from the received information, and based on the information, communication with the wireless communication device as a communication partner is performed within the ad hoc network. The wireless communication apparatus according to claim 1.   The radio according to claim 1 or 2, wherein the ad hoc communication means synchronizes with communication in the mobile communication network based on synchronization information received from the base station. Communication device.   An ad hoc network is constructed by a plurality of wireless communication devices including the wireless communication device according to any one of claims 1 to 3, and a TDD-CDMA system common to communication in a mobile communication network is used for communication in the ad hoc network. A wireless communication method that employs the same frequency band and performs communication in the ad hoc network in synchronization with communication in the mobile communication network.

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