CN101316155A - Wireless Transmission Method Using Distributed MIMO and Network Coding Technology - Google Patents

Abstract

The invention relates to a wireless transmission method which adopts distributed MIMO and network coding technology. The wireless data transmission usually cannot reach the ideal rate due to the limited emissive power, frequency spectra resource and so on. The specific steps of the method provided by the invention include transmission of source information, data reception and decoding at a trunk node, coding and data transmission at the trunk node, diversity reception and decoding at an information destination node. When a plurality of information source nodes all need to multicast the information to the information destination node, the information transmission to the trunk node is firstly carried out by the distributed MIMO mechanism, the trunk node adopts the network coding to carry out the distributed time-space coding. The communication between the trunk node and the information destination node also adopts the distributed MIMO mechanism. The method combines the MIMO mechanism with the network coding, which realizes the information transmission within a shorter time slot, also the antenna amount is reduced for the same transmission rate by utilizing the advantages of the network coding in the multicast.

Description

Wireless Transmission Method Using Distributed MIMO and Network Coding Technology

technical field

The invention belongs to the field of wireless network transmission, and relates to a wireless transmission method using a network coding technology and a distributed MIMO mechanism at the same time. The network coding technology enables more effective use of network bandwidth and reduces the number of antennas required by wireless nodes to meet the transmission rate requirements.

Background technique

In the past ten years, personal communications and mobile wireless communications have developed extremely rapidly. Wireless communication makes data transmission more convenient and faster. As long as it is within the coverage area of the network signal, data transmission can be performed anytime and anywhere, eliminating the geographical restrictions caused by the use of wired networks. With the development of wireless communication technology, wireless communication plays an increasingly important role in the social economy and people's daily life. At the same time, people have higher requirements for communication quality and channel capacity than before. However, factors such as bandwidth limitation, propagation attenuation, channel time-varying characteristics, noise interference, and multipath problems restrict the development of wireless communication services, making reliable high-speed wireless data transmission a very challenging subject.

MIMO (Multiple-Input Multiple-Output) technology is a major breakthrough in smart antenna technology in the wireless communication field. and receiving diversity) to improve the reliability of information transmission; using the spatial channels between different transceiver antennas, using spatial multiplexing technology to simultaneously transmit multiple data streams to increase the effectiveness of information transmission. Since the signals transmitted by each transmitting antenna simultaneously occupy the same frequency band, the capacity and spectrum utilization of the communication system can be doubled without additional bandwidth increase, greatly increasing the information transmission rate and improving information transmission performance.

The emergence of network coding (Network coding) has given people a new understanding of network routing methods, and may one day completely change the existing network transmission mechanism. In the working mode of network coding, the relay node no longer just forwards the received information, but forwards it after encoding. This network transmission mechanism can greatly improve the utilization efficiency of network bandwidth in the application of network multicast. When one or several nodes send data to several other nodes at the same time, it is often necessary to rely on the transmission of other nodes. In traditional networks, nodes acting as relays can only replicate, amplify, and forward received signals, which is sometimes a waste of network resources. Network coding technology breaks this limitation, it allows the relay node to encode the received information, and recombine multiple received data packets according to a specific algorithm before sending them out. If the minimum cut between the source node and the sink node is greater than the source information rate, then the sink node can completely recover the information of the source node through network coding.

Network coding can greatly improve the utilization rate of network bandwidth during multicast, and MIMO can greatly increase the transmission rate of wireless networks. If the network coding and the distributed MIMO transmission mechanism are combined, the advantages of MIMO and network coding will be played at the same time, thereby improving the information transmission rate of the wireless network.

Contents of the invention

The purpose of the present invention is to provide a wireless transmission method combining network coding and distributed MIMO mechanism, the method aims at improving the bandwidth utilization rate and transmission reliability of the wireless network. This method is a new type of wireless transmission method, which introduces the idea of network coding in the wireless network using distributed MIMO, that is, both the relay node and the sink node in the wireless network adopt multi-antenna diversity reception, so that information transmission Can be done in fewer time slots. Moreover, the relay node does not forward the received information directly, but sends it after network encoding. Using network coding can make more effective use of network bandwidth in a multicast application environment, and can reduce the number of required antennas when using the same number of time slots.

The specific steps of the method of the invention are information source information transmission, relay node data reception and decoding, relay node encoding and data transmission, and sink node diversity reception and decoding. details as follows:

The method for sending information source information is that each source node adopts a current mature wireless transmission method, and after performing channel coding and modulation on the information to be sent, it sends it to relay nodes within the transmission range in the form of broadcast. Since the relay node uses multiple antennas for reception, it can receive information from multiple source nodes at the same time, so the source nodes can simultaneously send information. This transmission method is similar to the MIMO mechanism using horizontally layered space-time coding. It needs to ensure that the number of receiving antennas is not greater than the number of sending antennas. The node selects an appropriate time slot to send information, so that the number of multi-channel information received by the relay node does not exceed the number of antennas it uses.

The relay node data reception and decoding is that the relay node uses multiple antennas to decode the information received in each time slot, and the decoding adopts the existing decoding layered space-time coding method; then according to The demodulation method corresponding to the modulation mode adopted by the information source node is demodulated; and then decoded according to the channel coding mode adopted by the information source information, and the decoding result is stored.

The relay node coding and data transmission is that the relay node sends the stored decoding information through network coding and distributed space-time coding, and the specific steps are:

(1) The relay node performs network coding on the decoded information obtained by decoding, and the coding adopts distributed random network coding or centralized network coding based on global information.

(2) The relay node performs distributed space-time coding according to the decoded information and the data obtained after network coding. When performing distributed space-time coding, the information after network coding of different relay nodes can be regarded as different layers of hierarchical space-time coding, and horizontal layered space-time coding can also be used to design appropriate distribution according to specific scenarios. space-time coding.

(3) The relay node uses the distributed MIMO mechanism to send the space-time coded information to the sink node. Since the correct decoding of space-time codes has certain requirements on the number of transmitting antennas and receiving antennas, the relay node also needs to use the space-time coding method, network topology, and other relay nodes and sink nodes. The number of antennas selects the sending time slot, so that other relay nodes and sink nodes can send the coded data under the limitation of the relationship between the number of sending antennas and receiving antennas required for decoding space-time coding.

The diversity receiving and decoding of the sink nodes is that each sink node adopts multi-antenna diversity to receive information, and restores the received information to complete original information through decoding. The specific steps are:

(1) The sink node uses a corresponding decoding method to decode the multi-channel information received by the antenna array according to the space-time coding method adopted by the relay node. The decoding method is an existing horizontal layered space-time coding decoding method or a decoding method corresponding to the adopted specific space-time coding. The decoding result is the information obtained after the relay node performs network coding.

(2) The sink node uses the decoding result in step (1) to decode according to the encoding function used by the relay node when performing network encoding, and recovers the original information. The encoding function of the network encoding adopted by the relay node can be specified in advance, and can also be included in the header of the data packet. According to the idea of network coding, the information network coding and decoding requirements received by the sink node can recover the complete source information.

The invention solves the problem of multicast communication in the wireless network. When there is no direct communication between the source node and the multiple sink nodes it wants to communicate with, a relay node is used to relay information. When multiple source nodes need to multicast their information to the sink node, they first transmit information with the relay node through the mechanism of distributed MIMO. The relay node uses multiple antennas to receive different source nodes at the same time. The received information Instead of simply forwarding data, it uses network coding first to encode the received information, and then performs distributed space-time coding. The communication between the relay node and the sink node also adopts the distributed MIMO mechanism. Multiple relay nodes form distributed multiple transmitting antennas, while the sink node receives information using multiple antennas. In this way, the information transmission of multiple source nodes and the information transmission of multiple relay nodes can be completed in fewer time slots. As long as the information obtained by the sink node after decoding the information received by multiple antennas meets the requirements of network coding and decoding, the complete original information can be recovered by decoding according to the network coding function adopted by the relay node.

The method of the invention combines the MIMO mechanism with network coding, so that information transmission can be completed in less time slots, and at the same time, the advantages of network coding in multicasting are used to reduce the number of antennas required to achieve the same transmission rate.

Description of drawings

Fig. 1 is a schematic diagram of network structure in the present invention;

Fig. 2 is a flow chart of the information transmission process in the present invention.

Detailed ways

The present invention is applicable to the scenario where multiple source nodes communicate with multiple sink nodes in a wireless environment. As shown in FIG. 1 , source node A wants to send a1 and a2 to sink nodes C and D, and source node B wants to send b1 and b2 to sink nodes C and D. Both C and D are not within the transmission range of A and B, and relay nodes M1, M2, and M3 are required to relay information. M1 and M2 are within the transmission range of A, M2 and M3 are within the transmission range of node B, C is within the transmission range of M1 and M2, and D is within the transmission range of M2 and M3. M2 is within the transmission range of M1 and M3, but M1 and M3 are not within the transmission range of each other. Assume that both A and B use single antennas to send information, relay nodes M1, M2, M3 all use two antennas to receive information, and sink nodes C and D use four antennas to receive information. It is also assumed that each node transmits at most one unit of data-encoded information in one time slot under the condition of using a single antenna.

As shown in Figure 2, the specific steps of the wireless transmission method using distributed MIMO and network coding technology are:

(1) Source information transmission

Since there are only two source nodes, and each relay node uses two antennas to send and receive information, which meets the requirement that the number of receiving antennas is not less than the number of sending antennas, two source nodes can transmit information at the same time. In time slot 1, source node A sends the result of channel coding and modulation of information a1 to M1 and M2, while source node B sends the result of channel coding and modulation of information b1 to M2 and M3. In time slot 2, source node A sends the result of channel coding and modulation of information a2 to M1 and M2, while source node B sends the result of channel coding and modulation of information b2 to M2 and M3.

(2) Relay node data reception and decoding

The relay node M1 receives the data sent by A in time slot 1, demodulates it and decodes it according to the channel coding method of A to obtain the information a1, and similarly obtains the information a2 in the time slot 2; the relay node M3 receives the data of B in the time slot 1 The sent data is demodulated and decoded according to B’s channel coding method to obtain information b1, and similarly obtain information b2 in time slot 2; Some decoding methods decode layered space-time coding, and then decode according to the channel error correction coding method adopted by source nodes A and B to obtain a1 and b1. Similarly, the data received in time slot 2 Decode to get a2 and b2. The relay nodes M1, M2, and M3 all store the source information obtained through decoding in their respective memories for use in the next encoding process.

(3) Relay node coding and data transmission

a. The relay node performs network coding according to the selected network coding method. In this example, a centralized network coding method based on global information is selected, and it is assumed that the sink node already knows the network coding function adopted by the relay node in advance. M2 XORs a1 to b1 to get x1, and XORs a2 to b2 to get x2.

b. Here, the distributed space-time coding adopts the simplest method, which is similar to the horizontal layered space-time coding method, and regards a1, a2, b1, b2, x1, x2 as the data after layering, and only Channel code it.

c. Since the sink nodes C and D both use four antennas to receive information, node C receives the information sent by the four antennas of M1 and M2, and D receives the information sent by the four antennas of M2 and M3, so the horizontal distribution is satisfied. Layer space-time coding requires the number of transmitting antennas and receiving antennas. M1, M2, and M3 can send information in the same time slot 3.

(4) Receive node diversity reception and decoding

d. The sink node C uses four antenna diversity to receive information, and first uses the existing decoding layered space-time coding method to decode, and then decodes according to the channel coding method used by the relay node to obtain a1, a2, x1, x2. Similar sink node D gets b1, b2, x1, x2.

e. C XORs x1 to a1 to get b1, x2 to XOR a2 to get b2; similarly, D XORs x1 to b1 to get a1, x2 to XOR b2 to get a2.

Claims (1)

1, adopts the radio transmitting method of distributed MIMO and network coding technique, it is characterized in that steps of the method are information source information transmission, regeneration node data reception and decoding, via node coding and data transmission, information destination node diversity reception and decoding;

Described information source information is sent as information that each information source node adopts wireless transmission method will need to send carry out chnnel coding and modulation after, send to via node in the transmission range with the form of broadcasting;

Described regeneration node data receives and decoding is that via node adopts many antennas that the information of receiving in each time slot is deciphered, and the interpretation method of demixing time space correspondence is adopted in decoding; The demodulation method of the modulation system correspondence that adopts according to information source node carries out demodulation then; Decipher according to the mode of the chnnel coding that information source information adopted again, the result who deciphers is stored;

It is that via node carries out the decoding information of storage to send behind network code and the distributed Space Time Coding that described via node coding and data send, and concrete steps are:

A. via node carries out network code with the decoding information that decoding obtains, and coding adopts distributed random network code method, or based on the centralized network coding method of global information;

B. the data that obtain after according to decoding information and network code of via node are carried out distributed Space Time Coding;

C. the information after via node adopts distributed MIMO mechanism with Space Time Coding is sent to information destination node;

Described information destination node diversity reception and decoding are that each information destination node adopts multi-antenna diversity to receive information, and the information that receives is recovered complete raw information by decoding, and concrete steps are:

D. information destination node is according to the mode of Space Time Coding that via node is taked, and the multiline message that uses corresponding interpretation method that aerial array is received is deciphered;

E. information destination node is utilized decode results, and the coding function that adopts when carrying out network code according to via node is deciphered, and recovers raw information.

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