JP4897753B2 - Radio relay apparatus and radio relay method - Google Patents

Description

  The present invention relates to a wireless relay device and a wireless relay method for relaying communication between wireless networks using frequency bands close to each other. In particular, the present invention relates to a radio relay apparatus and a radio relay method that perform relay processing between radio networks while reducing interference in a situation where leakage power due to proximity of an antenna corresponding to each radio network causes interference.

  A 2.4 GHz band channel called the ISM (Industry-Science-Medical) band that can be used without medical licenses for various devices such as medical equipment and home appliances, a wireless network that uses access control procedures by autonomous distributed control such as wireless LAN Is popular. This wireless network based on autonomous distributed control is characterized by low power and narrow communication area, and an access control method (for example, CSMA / CA) based on the premise that wireless networks using the ISM band interfere with each other is adopted. Yes.

  On the other hand, in the proximity frequency of this ISM band, there is a centralized wireless network that performs access control by TDD (Time Division Duplexing) or FDD (Frequency Division Multiplexing), such as WiMAX (Worldwide Interoperability for Microwave Access). Many of the wireless networks based on this centralized control require a license from a telecommunications carrier, and it is not assumed that wireless networks interfere with each other. It also features high power and wide area communication areas.

  In addition to the wireless LAN, the wireless network based on autonomous distributed control includes ZigBee, and the wireless network based on centralized control includes next-generation PHS (XG-PHS) in addition to WiMAX.

  In recent years, it is expected that these wireless networks will be integrated and complemented with each other, and wireless terminals having wireless interfaces corresponding to multiple wireless networks will appear in one housing. is doing. For example, a mobile terminal called a smartphone equipped with a wireless LAN and a third-generation mobile phone wireless interface, and a wireless relay device having a media conversion function for relaying between the wireless LAN and the third-generation mobile phone have been commercialized. By using this wireless relay device, the wireless LAN terminal can be connected to a wireless network in a wide area communication area such as a third-generation mobile phone, easily expanding the places where the wireless LAN can be used, and improving user convenience Can be improved.

FIG. 5 shows a configuration example of a wireless network including a wireless relay device.
In the figure, the wireless relay device 50 is wirelessly connected to the wireless LAN terminal 60 using the wireless LAN function, wirelessly connected to the WiMAX base station 70 using the WiMAX function, and connected to the network 80 via the WiMAX base station 70. To do. At this time, if the wireless LAN terminal 60 is within the service area of the wireless relay device 50, it can be connected to the network 80 via the wireless relay device 50.

  Such a wireless relay device 50 is connected to an antenna 54 connected to a WiMAX interface 51 that functions as a WiMAX terminal and a wireless LAN interface 52 that functions as a wireless LAN base station, for example, as shown in FIG. When the antenna 55 is close in the same casing, interference due to leakage power between the antennas occurs. Here, FIG. 6 (2) shows the relationship between the transmission power radiated outside the use frequency band of the wireless LAN and the reception power of WiMAX. Since the transmission power radiated outside the frequency band of use of the wireless LAN has a small propagation loss, it interferes with a WiMAX reception signal having a large propagation loss and greatly deteriorates the reception signal characteristics. The same applies to a WiMAX transmission signal and a wireless LAN reception signal.

  To deal with this problem, Non-Patent Document 1 proposes an interference avoidance method in which time sharing is performed between both wireless networks using the WiMAX sleep function, and channels are shared in a time division manner without simultaneous use. ing.

FIG. 7 shows a configuration example of a conventional wireless relay device 50 for avoiding interference.
In the figure, the wireless relay device 50 includes a WiMAX interface 51 that functions as a WiMAX terminal, and a wireless LAN interface 612 that functions as a wireless LAN base station. Here, the wireless LAN is a wireless network based on autonomous distributed control, and WiMAX is a wireless network based on centralized control. A scheduler 53 for determining the transmission / reception period of each wireless interface exists between both interfaces.

  The WiMAX interface (WiMAX terminal) 51 acquires a period during which transmission / reception can be performed from the WiMAX base station (sleep period information described later), and notifies the scheduler 53 of this information. The scheduler 53 calculates the communication occupation period of the wireless LAN based on this information and notifies the wireless LAN interface 52 of it. The wireless LAN interface 52 transmits / receives data to / from the wireless LAN terminal during the notified communication occupation period.

FIG. 8 shows a control sequence of the conventional wireless relay device 50.
In the figure, a WiMAX interface (WiMAX terminal) 51 transmits data in the downlink from the FCH (Frame Control Header), DL-MAP, UL-MAP, etc. at the head of a radio frame transmitted by the WiMAX base station 70. The reception timing and uplink transmission timing (WiMAX transmission / reception timing) are acquired and notified to the scheduler 53.

  Next, the WiMAX interface 51 transmits a sleep function request to the WiMAX base station 70. Here, the sleep function is intended to suppress the power consumption of the wireless terminal, and performs power saving control when the WiMAX interface 51 stops data transmission / reception during the sleep period. In the sleep function, a sleep period in which data transmission / reception is stopped and an active period in which normal transmission / reception is performed in accordance with instructions from the base station are alternately repeated.

  When receiving a sleep function request from the WiMAX interface (WiMAX terminal) 51, the WiMAX base station 70 determines a specific period as a sleep period and transmits the WiMAX sleep period information to the WiMAX interface 51. The WiMAX base station 70 stops data transmission / reception with the WiMAX interface 51 during the WiMAX sleep period.

  Next, when receiving the WiMAX sleep period information, the WiMAX interface 51 notifies the scheduler 53 of the start / end timing of the sleep period. The scheduler 53 calculates the wireless LAN communication occupation period based on the start / end timing of the sleep period, and notifies the wireless LAN interface 52 of it. The wireless LAN interface (wireless LAN base station) 52 and the wireless LAN terminal 60 transmit and receive data during the notified communication occupation period. The communication occupation period of the wireless LAN is a period during which WiMAX does not perform transmission / reception by the sleep function, and conversely, during the period during which WiMAX performs normal transmission / reception, the wireless LAN stops transmission / reception.

  In this way, when the wireless relay device uses the wireless LAN and WiMAX at the same time, as shown in FIG. 9, the influence of interference is exerted by the time division control in which the wireless LAN transmits and receives data during the WiMAX sleep period. It can be avoided.

In the above description, the wireless LAN and WiMAX are taken as examples of wireless networks that cause interference with each other. Can be taken.
J.Lei, Y.Yunsong, W.Xuyong, J.Segev, "Sleep Mode Timing Amendment Proposal", IEEE 802.16 WG Letter Ballot Recirc # 26a, January 2008 IEEE P802.11n / D3.02, Draft STANDARD for Information Technology Telecommunications and information exchange between systems Local and metropolitan area networks Specific requirements, 9.15 PSMP Operation, December 2007

  In a conventional wireless relay device, interference can be avoided by using time-sharing channels between the access-side wireless network and the relay-side wireless network. In other words, when one wireless network is in communication, the other wireless network is prevented from communicating, so that the communicable time in each wireless network is reduced, compared to the case where a single wireless network occupies a channel. Throughput decreases.

  By the way, the state where the wireless relay device is communicating with the wireless network includes transmitting and receiving, but when one wireless network is transmitting and the other wireless network is receiving, the transmitting side leaks power to the receiving side. If interference occurs and one radio network and the other radio network are simultaneously transmitting or receiving, no interference occurs between them.

  The present invention focuses on the fact that interference does not occur in simultaneous transmission and reception with respect to a plurality of wireless networks, and wireless relay capable of improving the throughput of each wireless network while avoiding interference between the plurality of wireless networks. An object is to provide a device and a wireless relay method.

According to a first aspect of the present invention, there is provided a wireless relay device that relays between a first wireless network and a second wireless network that use different frequency channels, a first interface unit corresponding to a terminal of the first wireless network, A second interface unit corresponding to a base station of the wireless network; and a scheduler that sets transmission / reception timing of the second wireless network in synchronization with transmission / reception timing of the first wireless network. The uplink transmission period and the downlink reception period of the first wireless network are acquired via the unit, and the same period as the uplink transmission period of the first wireless network is set as the downlink transmission period of the second wireless network. The same period as the downlink reception period of the first wireless network Set as an uplink reception period of the second wireless network, further to the end of the second downlink transmission period and an uplink receiving period of the radio network, and set shorter by the processing delay amount of the second wireless network configuration The second interface unit notifies the terminal of the second wireless network of the downlink transmission period and the uplink reception period of the second wireless network determined by the scheduler, and the transmission / reception timing of the second wireless network is notified. It is the structure to control.

The first wireless network of the wireless relay device of the first invention is a WiMAX network, the second wireless network is a wireless LAN, and the second interface unit uses a power saving (PSMP) procedure of the wireless LAN. Thus, the wireless LAN downlink transmission period is synchronized with the WiMAX network uplink transmission period, and the wireless LAN uplink reception period is synchronized with the WiMAX network downlink reception period .

According to a second aspect of the present invention, in the wireless relay method for a wireless relay device that relays between the first wireless network and the second wireless network using different frequency channels, the wireless relay device corresponds to a terminal of the first wireless network. 1 interface unit, a second interface unit corresponding to a base station of the second wireless network, and a scheduler for setting transmission / reception timing of the second wireless network in synchronization with transmission / reception timing of the first wireless network The scheduler acquires an uplink transmission period and a downlink reception period of the first wireless network via the first interface unit, and sets the same period as the uplink transmission period of the first wireless network to the second wireless network. Set as the downlink transmission period of the network and the first wireless network Set the same time and down link reception period as an uplink reception period of the second wireless network, further to the end of the second downlink transmission period and an uplink receiving period of the radio network, processing delay of the second wireless network The second interface unit notifies the terminal of the second wireless network of the downlink transmission period and the uplink reception period of the second wireless network determined by the scheduler, and sets the second wireless network. Controls network transmission and reception timing.

In the wireless relay method of the second invention, the first wireless network is a WiMAX network, the second wireless network is a wireless LAN, and the second interface unit uses a power saving (PSMP) procedure of the wireless LAN. Thus, the downlink transmission period of the wireless LAN is synchronized with the uplink transmission period of the WiMAX network, and the uplink reception period of the wireless LAN is synchronized with the downlink reception period of the WiMAX network.

  In the present invention, the uplink transmission period of the first wireless network and the downlink transmission period of the second wireless network are synchronized, and the downlink reception period of the first wireless network and the uplink reception period of the second wireless network Are synchronized. That is, the transmission / reception timing is adjusted so that the wireless relay device transmits to the first wireless network and the second wireless network simultaneously and receives simultaneously. This realizes highly reliable communication with no communication error due to interference between multiple wireless networks, and alternately repeats transmission and reception for each wireless network, increasing frequency utilization efficiency because it does not create idle time, Throughput of each wireless network can be improved.

  FIG. 1 shows an embodiment of a wireless relay device of the present invention. In the present embodiment, a wireless relay apparatus that relays between a WiMAX network and a wireless LAN in the network configuration shown in FIG. 6 will be described as an example. However, the present invention is not limited to WiMAX and wireless LAN, and the present invention is applied to both wireless networks. The present invention can be applied to relay between wireless networks capable of synchronous control of transmission / reception timing.

  In the figure, a wireless relay device 10 of this embodiment includes a WiMAX interface 11 that functions as a WiMAX terminal and a wireless LAN interface 12 that functions as a wireless LAN base station. Here, the transmission direction from the WiMAX base station 70 to the WiMAX interface (WiMAX terminal) 11 is DL (downlink), the reverse transmission direction is UL (uplink), and the wireless LAN interface (wireless LAN base station) 12 is wireless. The transmission direction to the LAN terminal 60 is DL, and the reverse transmission direction is UL. Furthermore, a scheduler 13 is provided between the WiMAX interface 11 and the wireless LAN interface 12 to determine the DL period and the UL period in the wireless LAN corresponding to the transmission / reception timing of the DL subframe and the UL subframe of the WiMAX frame.

FIG. 2 shows a control sequence of the wireless relay device 10 according to the embodiment of the present invention.
In the figure, a WiMAX interface (WiMAX terminal) 11 receives a DL subframe transmitted by the WiMAX base station 70, acquires synchronization time information from the preamble signal at the head thereof, and notifies the scheduler 13 of the DL time. The scheduler 13 determines a time reference in the wireless LAN based on the synchronization time information, and notifies the wireless LAN interface (wireless LAN base station) 12 of the time reference. The wireless LAN interface 12 synchronizes its timer with this time reference, and synchronizes the time between WiMAX and the wireless LAN.

  The WiMAX interface 11 detects the transmission / reception timing of the DL subframe and the UL subframe from FCH, DL-MAP, UL-MAP and the like at the head of the DL subframe, and notifies the scheduler 13 of the transmission / reception timing. The scheduler 13 calculates the UL period of the wireless LAN from the timing of the WiMAX DL subframe, calculates the DL period of the wireless LAN from the timing of the WiMAX UL subframe, and uses the wireless LAN interface as UL / DL period information of the wireless LAN. 12 is notified.

  The wireless LAN interface 12 transmits the DL / UL period information of the wireless LAN to the wireless LAN terminal 60 in the DL period of the wireless LAN. The wireless LAN interface 12 and the wireless LAN terminal 60 perform data transmission / reception processing in accordance with the DL period and UL period of the wireless LAN. That is, in the wireless relay device 10, both the WiMAX UL subframe and the DL period of the wireless LAN are synchronously transmitted, and both the WiMAX DL subframe and the wireless LAN UL period are synchronously received and are simultaneously transmitted. In addition, mutual interference is avoided by simultaneous reception.

  Note that the WiMAX network and the wireless LAN are synchronized based on time information obtained from the preamble signal of the WiMAX DL subframe, but due to the processing delay of the wireless LAN, for example, the DL period of the wireless LAN is delayed. It is conceivable that interference occurs due to the overlap of the WiMAX DL subframe and the transmission of the wireless LAN DL period and the reception of the WiMAX DL subframe. In this case, the scheduler 13 determines the wireless LAN delay time by comparing the UL period set for the wireless LAN and the reception timing of the UL data, and shortens the end of each of the DL period and the UL period by the delay time. Alternatively, a no-signal section may be set to avoid interference between the wireless LAN and WiMAX.

  Incidentally, the control of the DL period and the UL period in the wireless LAN can be realized by a PSMP (Power Save Multi-Poll) function which is a new power saving procedure defined by IEEE802.11n (see Non-Patent Document 2).

FIG. 3 shows an outline of the PSMP sequence.
In the figure, a wireless LAN base station 31 transmits a PSMP frame to wireless LAN terminals 32 and 33 to be connected. In the PSMP frame, a reception start time t1 and a transmission start time t3 assigned to the wireless LAN terminal 32, and a reception start time t2 and a transmission start time t4 assigned to the wireless LAN terminal 33 are described. The wireless LAN terminal 32 receives DL data from the reception start time t1 notified by the PSMP frame, transmits UL data from the transmission start time t3, and enters the power save mode at other times. The wireless LAN terminal 33 receives DL data from the reception start time t2 notified by the PSMP frame, transmits UL data from the transmission start time t4, and enters the power save mode at other times. Thus, the wireless LAN terminal performs transmission / reception at the timing notified by the PSMP frame, and stops data transmission / reception during other periods.

  In the present embodiment, the time t1 to t3 corresponds to the DL period of the wireless LAN, transmits a DL signal, and transmits a WiMAX UL subframe. Also, the time t3 to t5 corresponds to the UL period of the wireless LAN, and the UL signal is received and the WiMAX DL subframe is received.

FIG. 4 shows an operation example of the wireless relay device 10 according to the embodiment of the present invention.
In the figure, the radio frame structure in the WiMAX network is composed of a DL subframe and a UL subframe, and the DL subframe includes a header portion such as a preamble signal P, FCH, DL-MAP, UL-MAP, and DL data (DL burst). Consists of. A wireless LAN UL period is set for the WiMAX DL subframe, and a wireless LAN DL period is set for the WiMAX UL subframe.

  The WiMAX interface 11 of the radio relay apparatus receives the DL subframe of the radio frame # 1 transmitted from the WiMAX base station 70, and determines the WiMAX synchronization time information and the transmission / reception timing of the WiMAX DL subframe and UL subframe by the scheduler 13. Notify The scheduler 13 notifies the wireless LAN interface 2 of the time reference, and further notifies the wireless LAN UL / DL period information corresponding to the WiMAX DL subframe and the UL subframe. In the wireless LAN DL period synchronized with the WiMAX UL subframe, the wireless LAN interface 12 notifies the wireless LAN terminal 60 of the DL period and UL period of the wireless LAN using the PSMP frame, and transmits the DL data of the WiMAX frame. Relay transmission is performed as data D1 and D2. Here, a PSMP frame and a plurality of data D1, D2 are continuously transmitted at SIFS / RIFS intervals.

  The wireless LAN terminal 60 receives the data D1 and D2 in the DL period of the wireless LAN notified by the PSMP frame, and continuously transmits the data D3 and D4 to the wireless LAN interface 12 and receives the data in the DL period in the UL period. Block ACKs for the data D1 and D2 are transmitted in a batch.

  On the other hand, the WiMAX interface 11 receives the DL subframe of the wireless frame # 2 in the UL period of the wireless LAN. Here, similarly, the time synchronization process, the UL period and the DL period of the wireless LAN corresponding to the WiMAX DL subframe and the UL subframe are set, and the wireless LAN interface 12 notifies the wireless LAN terminal 60 with the PSMP frame. However, this process does not necessarily have to be performed for each frame.

  The wireless LAN interface 12 relays and transmits the DL data of the WiMAX frame # 2 as data D5 and D6 together with the PSMP frame to the wireless LAN terminal 60 in the DL period of the wireless LAN synchronized with the WiMAX UL subframe, and further the UL period. The block ACK for the data D3 and D4 received in is transmitted in a lump. The WiMAX interface 11 relays and transmits data D3 and D4 received in the UL period of the wireless LAN to the WiMAX base station as UL data in the UL subframe of the WiMAX frame # 2.

  As described above, in the wireless relay device, the timing at which the WiMAX interface 11 receives the DL subframe and the timing at which the wireless LAN interface 12 receives the UL data in the UL period are synchronized, and interference between received signals does not occur. Also, the timing at which the WiMAX interface 11 transmits the UL subframe and the timing at which the wireless LAN interface 12 transmits DL data in the DL period are synchronized, and both are signal transmissions, so that no interference occurs. In other words, when transmission and reception are alternately repeated on the WiMAX network side of the wireless relay device, transmission and reception are alternately repeated at the same timing on the wireless LAN side, and both prevent a decrease in throughput while avoiding interference. can do.

The figure which shows embodiment of the radio relay apparatus of this invention. The figure which shows the control sequence of the radio relay apparatus 10 of embodiment of this invention. The time chart explaining the outline | summary of a PSMP sequence. The time chart which shows the operation example of the radio relay apparatus 10 of this invention embodiment. The figure which shows the example of a wireless network structure containing a wireless relay apparatus. The figure explaining the interference factor of a radio relay apparatus. The figure which shows the structural example of the conventional radio relay apparatus 50 for interference avoidance. The figure which shows the control sequence of the conventional radio relay apparatus 50. The figure which shows the operation example of the conventional radio relay apparatus 50.

Explanation of symbols

10, 50 Wireless relay device 11, 51 WiMAX interface (WiMAX terminal)
12, 52 Wireless LAN interface (wireless LAN base station)
13, 53 Scheduler 54, 55 Antenna 60 Wireless LAN terminal 70 WiMAX base station 80 Network

Claims (4)

In a wireless relay device that relays between a first wireless network and a second wireless network using different frequency channels,
A first interface unit corresponding to a terminal of the first wireless network;
A second interface unit corresponding to a base station of the second wireless network;
A scheduler that sets transmission / reception timing of the second wireless network in synchronization with transmission / reception timing of the first wireless network;
The scheduler acquires an uplink transmission period and a downlink reception period of the first wireless network through the first interface unit, and sets the same period as the uplink transmission period of the first wireless network to the second period. down it is set as a downlink transmission period of the wireless network, the same period and the downlink reception periods of the first wireless network is set as an uplink reception period of the second wireless network, further of the second wireless network The configuration is such that the end of the link transmission period and the uplink reception period is set by reducing the processing delay of the second wireless network ,
The second interface unit notifies a terminal of the second wireless network of a downlink transmission period and an uplink reception period of the second wireless network determined by the scheduler, and transmission / reception timing of the second wireless network A wireless relay device characterized in that the wireless relay device is configured to control. The wireless relay device according to claim 1,
The first wireless network is a WiMAX network;
The second wireless network is a wireless LAN;
The second interface portion, the uses power-saving (PSMP) procedure of a wireless LAN, the downlink transmission period of the wireless LAN is synchronized with the uplink transmission period of the WiMAX network, the uplink of the wireless LAN A radio relay apparatus characterized in that a reception period is synchronized with a downlink reception period of the WiMAX network . In the wireless relay method of a wireless relay device that relays between a first wireless network and a second wireless network using different frequency channels,
The wireless relay device is
A first interface unit corresponding to a terminal of the first wireless network;
A second interface unit corresponding to a base station of the second wireless network;
A scheduler that sets transmission / reception timing of the second wireless network in synchronization with transmission / reception timing of the first wireless network;
The scheduler acquires an uplink transmission period and a downlink reception period of the first wireless network through the first interface unit, and sets the same period as the uplink transmission period of the first wireless network to the second period. down it is set as a downlink transmission period of the wireless network, the same period and the downlink reception periods of the first wireless network is set as an uplink reception period of the second wireless network, further of the second wireless network Set the end of the link transmission period and uplink reception period by shortening the processing delay of the second wireless network,
The second interface unit notifies a terminal of the second wireless network of a downlink transmission period and an uplink reception period of the second wireless network determined by the scheduler, and transmission / reception timing of the second wireless network The wireless relay method characterized by controlling. The wireless relay method according to claim 3 ,
The first wireless network is a WiMAX network;
The second wireless network is a wireless LAN;
The second interface portion, the uses power-saving (PSMP) procedure of a wireless LAN, the downlink transmission period of the wireless LAN is synchronized with the uplink transmission period of the WiMAX network, the uplink of the wireless LAN A wireless relay method, wherein a reception period is synchronized with a downlink reception period of the WiMAX network .

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