JP2005124121A - Radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus capable of avoiding the reduction of communication capacity as a whole network by suppressing a reception property from being deteriorated by an interference signal even when using the same frequency band by adopting a TDD-CDMA system common for communications in an ad hoc network and in a mobile communication network. <P>SOLUTION: The radio communication apparatus comprises ad hoc communication means for performing a radio communication with another neighboring radio communication apparatus by making an ad hoc network in conjunction with the other radio communication apparatus. The ad hoc communication means, when communicating with the other radio communication apparatus, adopt the TDD-CDMA system common to the mobile communication network to use the same frequency band and include an interference signal removal section 12d for removing an interference signal other than a desired signal transmitted from the other radio communication apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a TDD-CDMA wireless communication apparatus.

  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. 9, the recovery scheme includes an FDD (Frequency Division Duplex) that uses different frequency bands for the uplink from the mobile station to the base station and the 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. 10 shows a TDD-CDMA (Code Division Multiple Access) frame configuration in which this TDD scheme is adopted 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. 11, 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. Japanese Patent Application No. 2003-160576 discloses a technology related to the wireless communication device. 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.

  By the way, an ad hoc network is constructed by a plurality of wireless communication apparatuses (for example, wireless communication apparatuses A, B, C, and D) having the above-described configuration, and communication is performed between the wireless communication apparatuses A and B in the network. In this case, not only the desired signal transmitted from the wireless communication device B among the signals received by the wireless communication device A but also from other wireless communication devices (for example, wireless communication devices C and D) in the ad hoc network. Also included are transmitted signals, signals transmitted from base stations or mobile stations of mobile communication networks, and the same frequency band is used for transmission of each signal. There is a possibility that the wireless communication apparatus A becomes an interference signal. For this reason, there is a concern that the reception characteristics of the wireless communication device deteriorate due to the interference signal, and the communication capacity of the entire network decreases.

  The present invention has been made in view of such circumstances, and even when a common TDD-CDMA system is used for communication in an ad hoc network and a mobile communication network and the same frequency band is used, the reception characteristics due to interference signals are improved. It is an object of the present invention to provide a wireless communication apparatus that can suppress deterioration and avoid a decrease in communication capacity of the entire 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. While using the same frequency band, it has an interference signal removing means for removing an interference signal other than the desired signal transmitted from the other wireless communication apparatus.

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.)

  That is, the ad hoc communication means of the wireless communication device according to the present invention detects surrounding wireless communication devices having the above ad hoc communication function, and information about the wireless communication devices (for example, node information such as ID and node type, spreading code, etc.) And information on communication channels such as time slots) from a specific wireless communication device (master) and stored in the storage means, and then becomes a communication partner from the information stored in the storage means Information related to the wireless communication device is extracted, and based on the information, communication is performed with the wireless communication device serving as the communication partner in the ad hoc network.

  As the interference signal removal means, a well-known interference removal technique can be applied. For example, (1) the channel estimation value of each user and the spreading code assigned to each user are convolutionally multiplied. Generate a system matrix and multiply the received signal by this system matrix to extract the demodulated signal, joint detection (Joint Detection), and (2) generate a copy of the interference signal from each user signal and receive it It is possible to use an interference canceller that suppresses interference by subtracting from the signal. As for joint detection and interference canceller, see, for example, Ramjee Prasad, "CDMA mobile communication system", Science and Technology Publishing, June 1997, p. 319-369 and the like.

  According to a second aspect of the present invention, in the wireless communication apparatus according to the first aspect, the interference signal removing unit is configured to transmit the desired signal and the channel of the interference signal from a known signal (for example, midamble) included in the received signal. An estimated value is obtained, and the interference signal is removed by joint detection using the channel estimated value and a spreading code assigned to each wireless communication apparatus.

  According to a third aspect of the present invention, in the wireless communication apparatus according to the first aspect, the interference signal removing unit generates a replica of the interference signal and performs a process of subtracting the replica from the received signal. The interference signal is removed.

  According to a fourth aspect of the present invention, in the wireless communication device according to any one of the first to third aspects, the interference signal includes a signal from a base station or a mobile station of the mobile communication network. It is a feature.

  According to a fifth aspect of the present invention, in the wireless communication device according to any one of the first to third aspects, the interference signal is a signal that is exchanged with the desired signal among signals exchanged in communication within the ad hoc network. A signal that is not synchronized is included.

  The invention described in claim 6 is a wireless communication apparatus using a 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 surroundings. 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. While using the same frequency band, for each time slot set in the uplink and downlink of the mobile communication network, measure the size of the interference signal, and based on the measured value, in the ad hoc network A time slot used in communication is selected.

Here, as a method of selecting a time slot to be used for communication within an ad hoc network, either a time slot set for an uplink of a mobile communication network or a time slot set for a downlink can be selected by comparing the both. A method of selecting one as a time slot for ad hoc communication, and a method of selecting a time slot that satisfies a preset condition (for example, a condition related to the magnitude of an interference signal) as a time slot for ad hoc communication. However, any of them may be adopted.
For example, in the former method, when the time slot with the smaller amount of interference is selected as the time slot to be used for communication within the ad hoc network based on the measured value, power control is performed based on the amount of interference. The advantage is that low power can be achieved when doing so.
On the other hand, when the time slot with the larger amount of interference is selected, the power consumption of the wireless communication device increases, but the amount of interference from the wireless communication device decreases in the downlink of the mobile communication network, so the entire network The advantage of improving the characteristics can be obtained.

  The invention according to claim 7 is the wireless communication apparatus according to claim 6, wherein the ad hoc communication means performs output control of transmission power based on the measured value of the interference signal. .

  According to an eighth aspect of the present invention, in the wireless communication apparatus according to the sixth aspect, the ad hoc communication means is configured to transmit the interference signal for each time slot set in the uplink and downlink of the mobile communication network. Each size is measured, and a time slot used for communication in the ad hoc network is individually determined by comparing the measured value with a preset threshold value.

  According to a ninth aspect of the present invention, in the wireless communication device according to the eighth aspect, the ad hoc communication means is configured such that the magnitude of the interference signal in the time slot set in the uplink of the mobile communication network is equal to or less than a threshold value. In some cases, when the time slot set in the downlink of the mobile communication network is used for communication in the ad hoc network and the size of the interference signal in the time slot set in the downlink is equal to or less than a threshold value. The time slot set for the uplink is used for communication within the ad hoc network.

  According to a tenth aspect of the present invention, in the wireless communication device according to the ninth aspect, the size of the interference signal in the time slot set in the uplink of the mobile communication network is equal to or less than a threshold value and set in the downlink. The ad hoc communication means uses both time slots set for the downlink and the uplink for communication within the ad hoc network when the magnitude of the interference signal of the selected time slot is equal to or less than a threshold value. To do.

  According to the invention described in any one of claims 1 to 5, since the interference signal other than the desired signal included in the received signal is removed during communication in the ad hoc network, the ad hoc network and the mobile communication network Even when a common TDD-CDMA system is used for communication and the same frequency band is used, it is possible to suppress degradation of reception characteristics due to interference signals, and to avoid a decrease in communication capacity of the entire network. .

  According to the invention of claim 6 or 7, the magnitude of the interference signal is measured for each time slot set in the uplink and downlink of the mobile communication network, and based on the measured value. Since the time slot used for communication within the ad hoc network is selected and the transmission power output is controlled according to the measured value, interference between the ad hoc network and the mobile communication network is less likely to occur. Even when using this network, a good communication state can be secured.

  Furthermore, according to the invention according to any one of claims 8 to 10, the magnitude of the interference signal is measured for each time slot set in the uplink and downlink of the mobile communication network, and the measurement is performed. By comparing the value with a preset threshold value, the time slots used for communication within the ad hoc network are individually determined, so that both the uplink and downlink time slots can be used for communication within the ad hoc network. Can be used. For this reason, for example, it is possible to increase the communication efficiency in the ad hoc network as compared with the case where either the uplink or the downlink of the mobile communication network is selected and used in the communication in the ad hoc network. .

[First Embodiment]
FIG. 1 shows an embodiment of an ad hoc network constructed by a wireless communication apparatus according to the present invention. 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, the communication in the ad hoc network is performed in synchronization with the communication in the mobile communication network.

  FIG. 2 is a block diagram showing a main configuration of the first wireless communication apparatus. As shown in FIG. 2, 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.

  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, a demodulator 12b that demodulates the received signal that has passed through the band filter 12a into a baseband signal, Interference signal is removed by joint detection (Joint Detection) using channel estimation unit 12c that obtains channel estimation value from midamble included in baseband signal and channel estimation value and spreading code of each wireless communication device An interference signal removing unit (interference signal removing unit) 12d, and a received data processing unit 12e that performs various processes based on the demodulated signal from which the interference signal is removed. Note that a unique midamble is assigned in advance to each of the wireless communication devices 10 and 20, and the channel estimation value of each wireless communication device can be derived from the midamble included in the received signal. The interference signal removal unit 12d generates a system matrix by performing convolution multiplication of the spreading code assigned to each wireless communication device and the channel estimation value, and multiplies the baseband signal by the system matrix to generate a demodulated signal. To get to.

  The control unit 14 controls the transmitter 11 and the receiver 12 based on various kinds of information stored in the storage unit 15. The control unit 14 controls switching between transmission and reception and output control of transmission power ( Power control), switching control between an ad hoc network and a mobile communication network, synchronization control, and the like are performed. 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.

  When starting communication with other wireless communication devices in the ad hoc network, the magnitude of the interference signal is set for each time slot set for the uplink (Uplink) and downlink (Downlink) of the mobile communication network. Each is measured, and a process of selecting a time slot to be used for communication in the ad hoc network is performed based on the measured value. Furthermore, when communicating with other wireless communication devices in the ad hoc network, 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 an ad hoc network executed by the first wireless communication apparatus 10 having the above-described configuration will be described. Here, the wireless communication device 10 will be described as a node X, a wireless communication device that manages the entire ad hoc network will be referred to as a master, and a wireless communication device that performs wireless communication under the management of the master will be referred to as a slave.

This process is started, for example, when the SIR (Signal to Interference Ratio) of the ad hoc network is stronger than the mobile communication network or when the communication mode is switched to the ad hoc mode. The
First, the node X searches for a master in the ad hoc network, and based on the search result, performs a process of setting the node type of the node X to either master or slave. That is, the node X performs a process of detecting a pilot signal emitted from the master, and as a result, if the pilot signal can be detected, the node type is set to slave and the pilot signal cannot be detected. Set the node type to master.

  Here, when the node type is set to slave, the node X uses the preset shared channel (Common Channel) to set node information (for example, the ID and address of the node X) to the master. The process to transmit to is performed. Upon receiving the node information of the node X, the master updates the network information in the storage unit (node information of each slave, network resources, QoS (Quality of Service) parameters, etc.) based on this node information, and then A process of distributing network information to each slave (including node X) in the ad hoc network is performed. As a result, the node X is incorporated in the ad hoc network as a slave.

  On the other hand, when the node type is set to the master, the node X repeatedly transmits (broadcasts) the pilot signal every predetermined period, and monitors the control signal output from the slave periodically. A process of updating network information and a process of detecting the communication state of the slave are performed. Thereby, an ad hoc network having the node X as a master is constructed, and the ad hoc network is maintained and managed by the node X.

  Next, processing when communication is performed between nodes in the ad hoc network constructed as described above will be described. For example, when a node X is set as a slave, when the node X starts communication with another wireless communication device (hereinafter referred to as a node Y) set as a slave, The node X performs processing for designating the ID of the node Y to be a communication partner and transmitting a communication request message to the master. In response to this, the master refers to the network information in the storage unit, confirms the communication status of the node Y, and confirms network resources (for example, frequency band, spreading code, time slot, etc.) that can be used for communication. Then, processing for assigning a communication channel between the nodes X and Y is performed based on the network resource.

  At that time, the master transmits an interference signal (a signal from a mobile station of the mobile communication network, a base station 30) for each time slot set in the uplink (Uplink) and the downlink (Downlink) of the mobile communication network. The time slot with the smaller amount of interference (Public Interference Power) based on the measured value, and preferentially select the time slot to be used for communication within the ad hoc network. Thus, the most efficient communication channel is assigned as the communication channel between the nodes X and Y. For example, in the example of FIG. 3, since the amount of interference is smaller in the time slot set in the downlink than in the uplink, the time slot set in the downlink of the mobile communication network is used for communication within the ad hoc network. It is used as a time slot to be used.

  As the time slot selection method, for example, the size of the interference signal is measured only for the time slot set for the downlink, and if the measured value is larger than a preset threshold, the time slot is set for the uplink. It is also possible to adopt a method of selecting a set time slot as a time slot to be used for communication in an ad hoc network if the set time slot is small. In this embodiment, the time slot with the smaller amount of interference is preferentially selected as the time slot used for communication in the ad hoc network. For example, the communication characteristics of each node in the ad hoc network are improved. In addition to this, when it is required to improve the communication characteristics of the entire network, it is preferable to preferentially select the time slot with the larger amount of interference, contrary to the above. By doing so, it is possible to reduce the amount of interference from each node in the downlink of the mobile communication network, thereby improving the communication characteristics of the entire network.

  After the communication channel is assigned in this way, the master performs a process of returning the setting information in which the communication channel assignment is designated to the node X that has requested communication. At this time, the master also performs a process of updating the network information based on the setting information and storing it in the storage unit, and a process of distributing the updated network information to each slave in the ad hoc network.

  When the node X receives setting information necessary for communication with the node Y from the master, the node X stores the setting information in the storage unit 15 and then starts transmission / reception of a data signal directly with the node Y according to the setting information. To do. At that time, the node X performs power control so as not to interfere with a nearby wireless communication apparatus 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 is used as the maximum transmission power (allowable value). Transmission power output control is performed so as not to exceed this maximum value. Further, the node X receives a signal from the base station 30, extracts information for synchronization included in a predetermined time slot of the received signal, and performs communication in the mobile communication network based on the information for synchronization. A process for setting the communication timing with the node Y so as to match the timing is performed.

  Further, the node X performs processing for removing an interference signal other than the desired signal transmitted from the node Y when communicating with the node Y. The interference signal to be removed is different between the downlink and the uplink in the mobile communication network. That is, in the downlink, as shown in FIG. 4A, an interference signal is generated between a transmission signal from each node (wireless communication apparatuses 10 and 20) in the ad hoc network and a transmission signal from the base station 30. Composed. Here, a channel impulse response for a transmission signal from each node in the ad hoc network is likely to be flat fading because the communication distance is relatively short and multipath is unlikely to occur. On the other hand, since the transmission signal from the base station 30 has a longer communication distance than the distance between the nodes in the ad hoc network, the channel impulse response shows multipath fading. As a result, the received signal of the node X in the downlink is as shown in FIG. 4B, for example.

  When removing such an interference signal in the downlink, first, based on the midamble included in the received signal, a signal (desired signal) from the node Y as the communication partner, other nodes in the ad hoc network ( For example, the channel estimation values of the signals from the nodes A and B) and the signal from the base station 30 are obtained.

  Next, a signal to be removed is selected as an interference signal. Here, since the signal from the base station 30 is a signal having multipath fading characteristics as described above, it is a target of removal as an interference signal. On the other hand, signals from other nodes in the ad hoc network are excluded from removal if orthogonality between spreading codes is maintained. However, if the synchronization is lost and the orthogonality is poor, it becomes an interference signal because it becomes an interference signal. In addition, when the scale of the ad hoc network is large, a signal from a node located far away has a relatively large delay spread, and there is a possibility that a delayed wave exceeding the spreading code length arrives together with the direct wave. At this time, similarly to the signal from the base station 30, multipath fading occurs and inter-path interference occurs, so that the signal is a target for removal as an interference signal.

  Next, the interference signal is removed by performing joint detection using the selected interference signal, the channel estimation value of the desired signal, and the spreading code. As a result, SIR increases and reception characteristics are improved.

  On the other hand, in the uplink, as shown in FIG. 5 (a), an interference signal is composed of a transmission signal from each node in the ad hoc network and a transmission signal from a mobile station in the mobile communication network. Here, the channel impulse response to the transmission signal from each node in the ad hoc network is likely to be flat fading because the communication distance is relatively short and multipath is unlikely to occur. On the other hand, in the transmission signal from the mobile station, the channel impulse response shows flat fading or multipath fading depending on the communication distance. However, since the transmission power of the mobile station is relatively smaller than the transmission power of the base station 30, the transmission distance of the transmission signal is shorter than that of the base station 30. Note that the received signal of the node X in the uplink is as shown in FIG.

  When removing such an interference signal in the uplink, first, based on the midamble included in the received signal, a signal (desired signal) from the node Y as a communication partner, other nodes in the ad hoc network ( For example, channel estimates of signals from nodes A and B) and signals from mobile stations in the mobile communication network are obtained.

Next, as in the case of the downlink, a signal to be removed is selected as an interference signal. Here, signals from other nodes in the ad hoc network are excluded from removal if orthogonality between spreading codes is maintained. However, if the synchronization is lost and the orthogonality is poor, or if the ad hoc network is large and the amount of delay exceeds a predetermined amount (1 chip), it becomes an interference signal and is subject to removal. On the other hand, a signal from a mobile station in a mobile communication network has fading characteristics different from signals from other nodes in the ad hoc network. That is, depending on the communication distance and communication environment, it may have flat fading characteristics or multipath fading characteristics. However, since these signals have different propagation times and are out of synchronization, they all become interference signals and are therefore subject to removal.
After selecting the interference signal in this manner, the interference signal is removed by performing joint detection using the interference signal, the channel estimation value of the desired signal, and the spreading code. As a result, the SIR increases and deterioration of reception characteristics can be prevented.

  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 the interference signal other than the desired signal included in the received signal is removed during the communication in the ad hoc network, the TDD-CDMA system common to the communication in the ad hoc network and the mobile communication network is adopted to have the same frequency. Even when bands are used, it is possible to suppress degradation of reception characteristics due to interference signals, and avoid a reduction in communication capacity of the entire network.

  Further, for each time slot set in the uplink and downlink of the mobile communication network, the size of the interference signal is measured, and based on the measured value, the time slot with the smaller amount of interference is determined in the ad hoc network. Selected as a time slot to be used for communication within the network, and output power control is performed according to the measured value, so that interference is less likely to occur between the ad hoc network and the mobile communication network. Even when using this network, a good communication state can be secured.

  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. 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.

  When an ad hoc network is constructed in an area where interference from the mobile communication network is strong, for example, a configuration as shown in FIG. 6 can be adopted as the interference signal removal means. As shown in FIG. 6, this interference signal removing means includes a cellular signal detection unit 41 that obtains data of a signal (hereinafter referred to as a cellular user signal) from a base station or a mobile station of a mobile communication network and a channel impulse response. A cellular signal regenerator 42 for generating a replica of the cellular user signal using the cellular user signal data and the channel impulse response, a memory 43 for temporarily storing the received signal, and a cellular signal from the received signal. A calculation unit 44 that performs calculation processing for subtracting a replica of the user signal and an ad hoc signal detection unit 45 that detects a desired signal from the reception signal from which the cellular user signal has been removed are provided.

  In this interference signal removing means, first, received signals are respectively input to the cellular signal detector 41 and the memory 43. The cellular signal detection unit 41 detects only the cellular user signal from the received signal using joint detection, and performs processing for obtaining data of the cellular user signal and a channel impulse response. Next, the cellular signal regenerator 42 performs processing for generating a replica of the cellular user signal using the cellular user signal data received from the cellular signal detector 41 and the channel impulse response.

  Thereafter, the reception signal is input from the memory 43 to the calculation unit 44, and a replica of the cellular user signal is input from the cellular signal regeneration unit 42 to the calculation unit 44. In the calculation unit 44, the replica of the cellular user signal is received from the reception signal. By subtracting, a process for removing the interference signal from the mobile communication network is performed. Next, the ad hoc signal detection unit 45 performs processing for detecting a desired signal (a signal from a node serving as a communication partner in the ad hoc network) from the received signal from which the cellular user signal has been removed. Here, since signals (ad hoc user signals) from each node in the ad hoc network are mainly affected by flat fading, data can be detected by a general demodulation method, but synchronization can be achieved. If the user signal is not received and the user signal is received by multipath, data detection is performed using joint detection. As a result, a desired ad hoc user signal without interference from the mobile communication network can be obtained.

  According to this interference signal removing means, the influence of interference can be greatly suppressed even in an area where interference from the mobile communication network is strong. For this reason, for example, in a wireless communication system that performs spreading using a scrambling code and a channelization code, a mobile communication network and an ad hoc network are assigned different scramble codes. The same channelization code as that used in the body communication network can be assigned to the communication channel in the ad hoc network, and all channelization codes can be used for communication in the ad hoc network. Therefore, the communication capacity of the entire ad hoc network can be greatly increased.

[Second Embodiment]
In the first embodiment described above, one of the time slots set for the uplink (Uplink) and the downlink (Downlink) of the mobile communication network is compared by comparing both. The time slot used for communication within the ad hoc network (hereinafter, referred to as a time slot for ad hoc communication) is selected. In the second embodiment, the time slot satisfies a preset condition. Is selected as a time slot for ad hoc communication.

  Specifically, when communication is performed between nodes constituting an ad hoc network, a radio communication device (master) that manages the entire ad hoc network assigns a communication channel to an uplink and a downlink of the mobile communication network. For each time slot set to 1, the magnitude (interference power) of the interference signal (signal from the mobile station of the mobile communication network, signal from the base station 30) is measured, and these measurement values are set in advance. In comparison with the threshold value, it is determined whether or not the interference power in each time slot is less than or equal to the threshold value. If the result of the determination is that the interference power in the time slot set for the uplink is less than or equal to the threshold value, ad hoc While assigning a time slot set for the downlink as a communication time slot, If the interference power of the set time slot exceeds a threshold, performing a process of excluding the set time slot to the downlink time slots for ad hoc communication. If the interference power of the time slot set for the downlink is equal to or less than the threshold as a result of the above determination, the time slot set for the uplink is assigned as the time slot for ad hoc communication, while the time slot is set for the downlink. When the interference power of the selected time slot exceeds the threshold value, processing for excluding the time slot set for the uplink from the time slot for ad hoc communication is performed.

  As a result, for example, as shown in FIG. 7, the interference power (Interference Power) in the time slot set for the uplink of the mobile communication network is equal to or less than the threshold (threshold) and the time slot set for the downlink When the interference power is less than or equal to the threshold, both downlink and uplink time slots are allocated as ad hoc communication time slots.

Here, since the interference power depends on the distance (that is, it becomes larger as the distance is shorter), in the radio communication device configuring the ad hoc network, it is possible to estimate the distance from the interference power in the uplink to the mobile station. It is possible to estimate the distance from the interference power in the downlink to the base station.
On the other hand, when the distance between the ad hoc network and the mobile station is short, the interference received from the ad hoc network in the downlink increases in the mobile station, and when the distance between the ad hoc network and the base station is short, the base station Causes greater interference from ad hoc networks.

  Therefore, when it is estimated that the interference power in the time slot set for the uplink is less than the threshold and the ad hoc network and the mobile station are separated from each other by a certain distance, the time slot set for the downlink is ad hoc. By using the communication in the network, the influence of the communication in the ad hoc network on the mobile station can be reduced. Similarly, when it is estimated that the interference power in the time slot set for the downlink is equal to or less than the threshold and the ad hoc network and the base station are separated from each other by a certain distance, the time slot set for the uplink is By using the communication in the ad hoc network, the influence of the communication in the ad hoc network on the base station can be reduced.

  The threshold value is set in advance to a value that does not affect other wireless communication apparatuses outside the ad hoc network even if communication is performed within the ad hoc network. This threshold value can be determined based on, for example, the reliability and bit rate required for the system, the number of users to be used, and the like, and may be stored in advance in a wireless communication apparatus that can be a master. The wireless communication device set as the master may acquire information necessary for threshold determination from the base station and update it appropriately. In addition, the same value may be used for the threshold value for the uplink and the downlink, or different values may be used for the threshold according to the difference in required performance required for each channel.

  According to the second embodiment, the magnitude of the interference signal is measured for each time slot set in the uplink and downlink of the mobile communication network, and the measured value and a preset threshold value are determined. As a result of the comparison, the time slots used for communication within the ad hoc network are individually determined, so that it is possible to use both the uplink and downlink time slots for communication within the ad hoc network at the maximum. Compared with the case where only one of the uplink and downlink of the mobile communication network is selected as the ad hoc communication time slot as in the first embodiment, the communication efficiency in the ad hoc network is greatly increased. It becomes possible. In general, when looking at the ratio of uplink and downlink per frame of TDD-CDMA in a mobile communication network, the downlink is almost always larger. For example, only uplink is used for communication in an ad hoc network. However, according to the present embodiment, it is possible to use both the uplink and the downlink, so that the above-described problem occurs. Therefore, communication can be performed efficiently.

It is a schematic block diagram which shows one Embodiment of the ad hoc network constructed | assembled by the radio | wireless communication apparatus which concerns on this invention. It is a block diagram which shows the principal part structure of the 1st radio | wireless communication apparatus of FIG. It is a schematic diagram explaining the selection method of the time slot used by the communication in an ad hoc network. It is a schematic diagram explaining the interference signal which generate | occur | produces in the downlink of a mobile communication network. It is a schematic diagram explaining the interference signal which generate | occur | produces in the uplink of a mobile communication network. It is a figure which shows the modification of the receiver of FIG. It is a schematic diagram explaining 2nd Embodiment of the selection method of the time slot used by the communication in an ad hoc network. 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 (10)

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. And adopting a TDD-CDMA system common to the mobile communication network, using the same frequency band, and having an interference signal removing means for removing an interference signal other than a desired signal transmitted from the other wireless communication device. A wireless communication apparatus.   The interference signal removal means obtains the desired signal and the channel estimation value of the interference signal from the known signal included in the received signal, and uses the channel estimation value and the spreading code assigned to each wireless communication device, The radio communication apparatus according to claim 1, wherein the interference signal is removed by joint detection.   2. The radio communication apparatus according to claim 1, wherein the interference signal removing unit removes the interference signal by generating a replica of the interference signal and performing a process of subtracting the replica from the received signal. .   The radio communication apparatus according to claim 1, wherein the interference signal includes a signal from a base station or a mobile station of the mobile communication network.   The interference signal includes a signal that is not synchronized with the desired signal among signals exchanged in communication within the ad hoc network. Wireless communication device. 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. The same frequency band is adopted by adopting a TDD-CDMA system common to the mobile communication network, and the magnitude of the interference signal is set for each time slot set in the uplink and downlink of the mobile communication network. And a time slot used for communication in the ad hoc network is selected based on the measured value.   7. The wireless communication apparatus according to claim 6, wherein the ad hoc communication means performs transmission power output control based on the measured value of the interference signal.   The ad hoc communication means measures the size of the interference signal for each time slot set in the uplink and downlink of the mobile communication network, and compares the measured value with a preset threshold value. The wireless communication apparatus according to claim 6, wherein a time slot used for communication in the ad hoc network is determined.   The ad hoc communication means ad hoc the time slot set in the downlink of the mobile communication network when the magnitude of the interference signal in the time slot set in the uplink of the mobile communication network is equal to or less than a threshold value. Use in communication within the network, and use the time slot set in the uplink for communication within the ad hoc network when the size of the interference signal in the time slot set for the downlink is below the threshold. The wireless communication apparatus according to claim 8, characterized in that:   When the magnitude of the interference signal in the time slot set for the uplink of the mobile communication network is less than or equal to the threshold and the magnitude of the interference signal for the time slot set for the downlink is less than or equal to the threshold, The wireless communication apparatus according to claim 9, wherein the communication unit uses both time slots set for the downlink and the uplink for communication within the ad hoc network.

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