124 results about "Physical layer network coding" patented technology

This invention provides a method for jointly optimizing network coding, channel coding, and signal constellations in non-coherent wireless multiple-input multiple-output (MIMO) wireless relay networks for the case when transceivers cannot obtain any knowledge of channel state information (CSI) due to high-speed mobility of the transceivers. In the relay networks, two terminal transceivers simultaneously transmit data to an intermediate relaying transceiver, which in turn broadcasts mixed data using physical-layer network coding to both terminals. The embodiments of this invention exploit different blind space-time trellis-coded modulations (ST-TCM) for each user, whose codebook is jointly generated over a Grassmannian manifold. The method is provided by exponential mapping with affine-lattice convolution for joint optimization of channel coding, modulations, and network coding. The method is designed for fast fading channels with and without interleaving. The method significantly improves performance in non-coherent bidirectional relaying MIMO networks.

The invention discloses a symbol-based physical-layer network coding method for a two-way relay communication system. The method comprises the following steps that: in a first time slot, during the receiving of information through a relay node, two source nodes send respective modulated signals to the relay node respectively, and the relay node performs self-correlation operation on the received superposed signals to obtain a self-correlation matrix and detects a network coding symbol to be broadcast from the self-correlation matrix by using a maximum-likelihood (ML) detection algorithm to reduce a detection space of the network coding symbol, so the difficulty of signal detection is reduced, a receiving diversity gain is obtained, and the error code performance of the system is guaranteed; and in a second time slot, during the broadcasting of the information through the relay node, the relay node broadcasts the detected network coding symbol, and the two source nodes respectively decode the received signals by using a self-interference elimination method to obtain the information of the opposite-side node, so a communication process is finished. The invention has the advantages that: the operation complexity of a relay processing signal is reduced by using the characteristics of an M-ary phase shift keying (MPSK) signal; the receiving diversity gain is obtained; and the method is applicable to an MPSK modulation system at symmetric and asymmetric speed rates under a two-way relay channel.

The invention discloses a physical layer network coding and design method for a bidirectional relay channel of a cellular system, which is characterized by comprising the steps as follows: a base station precodes sent signals and then sends to a relay node, and at the same time, users also respectively send respective information to a relay end; the relay node receives the information sent by the base station and users and performs physical layer network coding hybrid, the signals subjected to physical layer network coding are precoded so as to ensure that the signals received by one user can not be disturbed by other users, and the signals are forwarded; and the users and base station respectively receive the signals forwarded by the relay node, and disturbing signals in respective received signals are respectively eliminated so as to perform demodulation. Compared with the existing technical method of time division multiplexing bidirectional relay physical layer network coding, the invention greatly reduces the time slot required for completing uplink/downlink communication transmission, supports the communication of more users and improves the outage probability of each user and the ergodic capacity of the overall system.

The invention provides a wireless communication method for realizing physical layer network coding in a multi-user channel, relates to the field of wireless communication, and aims to realize wireless signal transmission based on physical layer network coding in a network containing a plurality of user nodes but only one relay node. The method comprises the steps that coded bit information of N users is produced, subjected to multiple frequency-shift keying (MFSK) modulation and sent to the relay node; signals are directly added by the relay node to obtain a sum signal, the sum signal is judged and then mapped as network coded information, and the network coded information is subjected to MFSK modulation and then broadcast; the N users respectively conduct MFSK demodulation on a received signal; the relay node broadcasts demodulated information of the users one by one, and the N users respectively conduct MFSK modulation on the demodulated information; and finally, the obtained user information and the network coded information are subjected to bitwise bit exclusive or operation to complete the whole process of physical network coding, thereby realizing wireless communication based on physical layer network coding in the multi-user channel. The wireless communication method is suitable for wireless communication.

The invention discloses an M-ary quadrature amplitude modulation (MQAM)-mode-based physical-layer network coding wireless communication method, and relates to the field of wireless communication. The problem of low system performance caused by three timeslots and four timeslots required by the conventional transmission mode in a two-way relaying channel is solved. The method specifically comprises the following steps of: performing MQAM on the coded bit information S1 and S2 of users N1 and N2 to obtain modulated signals s1(t) and s2(t), simultaneously transmitting the signals s1(t) and s2(t) to a relay node NR, directly adding the signals s1(t) and s2(t) by using the relay node NR to obtain a sum signal rR(t), judging the rR(t), and further mapping a judgment result into the network coding information SR of the S1 and the S2; and performing MQAM on the SR again by using the relay node NR, broadcasting the modulated signal sR(t) to the users N1 and N2, demodulating the received sR(t) by the N1 and the N2 respectively, and performing by-the-bit XOR operation on the obtained network coding information SR and transmitted information stored in a local cache of one user to obtain the bit information of the other user, so that an information exchange process is implemented. The method is applied to the wireless communication.

The invention relates to a wireless communication method, in particular to a wireless communication method of physical network coding in a flat frequency-selective fading channel, based on a two-way relay model. The method eliminates interferences between a real part and an imaginary part of a modulation signal, and reduces the complexity of a relay receiver. The method comprises the steps that two information source nodes perform QPSK (Quadrature Phase Shift Keying) modulation, precoding, carrier modulation and re-carrier modulation on information data, and then send the information data to a relay node; the relay node sums received signals, then performs the carrier demodulation on the summed signals, and solves broadcast data by judging and mapping; then, the relay node performs the QPSK modulation and the carrier modulation on the broadcast data, and broadcasts and sends the broadcast data; the information source nodes perform the carrier demodulation on carrier modulation signals received with broadcast; after the information source node S1 and the information source node S2 perform signal processing on the signals being subjected to the carrier modulation respectively, the information source node S1 obtains an estimated value of the signals sent by the information source node S2; and the information source node S2 obtains an estimated value of the signals sent by the information source node S1, thereby accomplishing communication. The method is applied to wireless communication.

The invention relates to the wireless communication technical field, specifically relates to a communication method based on fountain codes and physical layer network coding. In adoption of the method of the invention, the performance of a wireless communication system can be further improved; the network throughput of the communication system can be improved; the bit error rate of the communication system can be reduced; and the problems such as reducing the spectral efficiency, channel congestion and reducing the transmitting efficiency resulted from enhancing the communication reliability in an ARQ (Automatic Repeat Request) or FEC (Forward Error Correction) technique can be avoided. According to the communication method of the invention, Raptor coding is carried out to source node signals at a first time slot; Raptor decoding and physical layer network coding are carried out to mixed signals at a second time slot; broadcasting is carried out; finally each source node is reduced; the signals of the opposite side nodes are obtained; and therefore, the information interaction is finished.

The invention provides a physical layer network coding system and method based on FQPSK (Feher patented Quadrature Phase Shift Keying) modulation. The method is characterized in that a transmitting terminal unit comprises the following steps: A, respectively emitting raw information xA and xB by two signal sources; B, respectively modulating the two pieces of raw information xA and xB after completion of respective modulation to a high-frequency carrier to be changed into emission signals zA and zB; and C, expressing the mixed signals received by a relay module as YR(t)={zA(t)+n(t)}+{zB(t)+n'(t)}, where YR(t) represents the received mixed waveform signals. The method has the benefits that the FQPSK modulation is adopted to perform constant envelope protection for the physical layer network encoded signals, which successfully solves the problem of detection and classification for stacked signals at the relay; and a waveform cluster classification criteria replaces a constellation classification criteria so as to avoid the defect that the FQPSK modulation constellation is ruleless.

A scheduling method and a scheduling apparatus based on physical layer network coding for bidirectional traffic are provided. The method includes setting up paths passing through a node to perform the physical layer network coding of the bidirectional traffic of sessions that pass through the node. The method further includes requesting, from neighboring nodes of the node, information to be used to schedule the sessions for the physical layer network coding. The method further includes scheduling the sessions for the physical layer network coding based on a queue differential of each session that is calculated based on the information, and a rate of each link of each session.

The invention discloses a bidirectional relay transmission system and method. The transmission method comprises the following steps of: in the multiple access transmission time slot, all the users pre-code the signal vectors to be transmitted and simultaneously transmit the pre-coded information flow to a relay node; the relay node receives the signals and decodes the received signals based on physical layer network codes; and in the broadcast time slot, first relay-user joint pre-coding design is carried out and then the relay node broadcasts the pre-coded signals to all the users; and the users demodulate the received signals and extract the required signals according to the signals transmitted by themselves in the previous time slot. By adopting the system and the method, the multi-antenna X-shaped bidirectional transmission system which completes terminal information exchange of the two users in two time slots is realized, the degree of freedom of the system is maximized and the system performances are promoted.

The invention relates to the technical field of wireless communication, specifically relates to a communication method based on LDLCs (Low Density Lattice Code) and physical layer network coding. The communication method aims at further improving the performance of a wireless communication system, improving the network throughput of the communication system, reducing the bit error rate of the communication system and improving the transmission capacity in an additive white gaussian noise channel. According to the communication method provided by the invention, through carrying out LDLC coding to the source node signals at a first time slot, carrying out LDLC decoding and physical layer network coding to mixed signals at a second time slot and broadcasting, finally, each source node is reduced and the opposite side node signals are obtained, thus finishing information interaction.

The invention relates to a spatial multiplexing method for network coding of a physical layer, belonging to the technical field of wireless communication. A signal transmission method of the spatial multiplexing method comprises two transmission phases: a multiple-access (MAC) stage and a broadcast (BC) stage. In the MAC stage, two users hoping to carry out two-way communication transmit precodedinformation to a repeater simultaneously, the repeater carries out maximum likelihood detection of network coding of the physical layer on superposed signals from different users so as to further obtain network coding symbols directly; and in the BC stage, the network coding symbols are broadcast back to the users by the repeater, and the users extract information of another user by utilizing self information after decoding precoded signals. The method effectively improves frequency spectrum utilization ratio and energy utilization efficiency of a two-way repeating network, realizes multithread high-speed transmission and reduces the decoding complexity of the repeater.

The invention discloses a physical layer network coding-based nonsynchronous superposed signal decoding system and method, belonging to the technical field of wireless relay communication. The layer network coding-based nonsynchronous superposed signal decoding system comprises a channel module and three radio devices, wherein the two radio devices are used as two source nodes, the other radio device is used as a relay node, the two source nodes are used for carrying out wireless communication through the relay node, the relay node adopts a physical layer network coding relay mode; the two source nodes comprise a signal source module, a channel coding module, a modulation module, a demodulation module and a subtraction module; and the relay node comprises a coherence demodulator module, a judgment module, a channel decoding module and a modulation module. The invention completely considers nonsynchronous condition, error rate performance and computing complexity, and is more suitable for decoding a nonsynchronous superposed signal in a practical platform, thereby being more beneficial to realization of network coding of a physical layer.

The invention discloses a wireless communication method of physical layer network coding based on a multi-frequency-shift keying (MFSK) modulation mode, and relates to the field of wireless communication. The wireless communication method of the physical layer network coding based on the MFSK mode improves the performance of a wireless communication system through the time slot number of compressed data communication. According to the wireless communication method, the encoded bit information transmitted by two user nodes is respectively modulated in an MFSK mode and is simultaneously transmitted to relay nodes, total signals are obtained by the addition of the relay nodes, are judged and mapped as the bit information of network encoding, the bit information is modulated in an MFSK mode and broadcasted to the two user nodes, the two user nodes respectively demodulate the broadcast modulation signals and respectively output corresponding modulation signals saved in a local cache after bitwise or calculation, and therefore the wireless communication method of the physical layer network coding based on the MFSK mode is realized. The wireless communication method of the physical layer network coding based on the MFSK mode is suitable for wireless communication of the physical layer network coding based on the MFSK mode.

The invention relates to a method for resisting interference in a multiple-group multiple-user two-way relay network. The method is implemented through the following two stages: 1) a multiple-access stage, at which all users simultaneously transmit information to a relay node; and 2) a broadcast stage, at which the relay node conducts certain processing to signals received at the multiple-access state and then broadcasts to all users, and the users conduct decoding to complete two-way information exchange. The processing operation which is conducted by the relay node to the naturally superposed signals which are received at the multiple-access state is the core of the invention, and comprises the following steps that: a) the relay node decodes the received signals to restore information of users; b) physical-layer network coding is conducted to the information of the users who belong to the same group; and c) superposition coding is conducted to network coded symbols obtained in the step b and then the network coded symbols are broadcasted to all users in the form of time-space codes. By adopting the physical-layer network coding and the superposition coding, the situation that system performance is deteriorated due to interference between groups and interference in the group can be resisted. Specifically, the physical-layer network coding can eliminate the interference in the group and the superposition coding can resist the interference between groups. According to theoretical analysis and simulation experiments, by using the method, better system performance can be obtained.

The invention relates to a signal detecting method for a multi-antenna two-way relay channel. The method is characterized in that a physical layer network coding technology is adopted in the multi-antenna two-way relay channel, and the bit error rate of a system is reduced by adopting a combined detection and interference elimination algorithm and a combined modulation and demodulation scheme at a relay node. According to the combined detection and interference elimination algorithm, the conventional least mean-square error detection algorithm is applied to the multi-antenna two-way relay system, and the estimated value of source node transmitting signals, which is obtained by detection, is subjected to parallel interference elimination, so that mutual interference between the source node transmitting signals can be furthest reduced. In addition, a new combined modulation constellation mapping scheme is proposed at the relay node according to the modulation modes of two source nodes and based on the constellation point design criteria of minimum Euclidean distance maximization. Compared with a relay node signal processing scheme for completing information combination by using xor operation, the method under the asymmetrical transmission mode that different modulation modes are adopted at the two source nodes has the advantages that the minimum Euclidean distance between relay node broadcasting signals is prolonged, the bit error rate of the system is reduced, and the transmission reliability of a two-way cooperative communication system is improved.

The invention relates to a communication method based on MIMO-OFDM and physical layer network coding, which belongs to the technical field of wireless communication. The communication method aims to further improve the performance of a wireless communication system, increase network throughput of a communication system, and reduce error rate of the communication system. The invention provides a communication method based on MIMO-OFDM and physical layer network coding. The communication method comprises OFDM modulation at the phase of multiple access and STBC coding; signal receiving and signal superposing at the relay node; superposing signal maximum likelihood decoding, physical layer network coding and STBC coding; broadcast signal receiving and opposite side information restoring. The communication method based on MIMO-OFDM and physical layer network coding is advantageous in that network throughput of the communication system is increased, and the error rate of the communication system is reduced; compared with the traditional physical layer network coding, the throughput of the communication method of the invention is 1.5 times that of the traditional physical layer network coding; when the error rate BER is 10-5, the coding gain of the communication method of the invention is approximately 0.8dB.

The invention provides a technology used in a mobile communication relay system, which conducts an unequal error protection combination to data parts with different important grades in two receiving signals at the relay node. Comparing to the conventional equal error protection combination method, this method of the invention can improve the transmission performance of data stream and is easy to implement. The technology of the invention combines a physical layer network encoding technique and a superposition encoding technique. At the relay node the weight and combination of data with different important grades in two receiving signals is realized according to different energy coefficients, thereby the unequal error protection combination is realized.

The invention discloses a full diversity multi-antenna two-way relay receiving method based on combination of a Dempster-Shafer evidence theory and a physical-layer network coding. Firstly, a multi-antenna two-way relay model without direct link is built; then, performance and defects of the prior multi-antenna two-way relay receiving algorithm based on a decode-and-forward network coding and the physical-layer network coding are analyzed, moreover, according to the defects of the prior algorithm, the full diversity multi-antenna two-way relay receiving method based on combination of the Dempster-Shafer evidence theory and the physical-layer network coding is provided. According to the invention, uncertainty generated by fading channels and noise is described through a basic probability assignment function, then, the uncertainty of received signals is reduced at a receiving end through a Dempster's rule, and finally, reliable transmission signals are obtained through a maximum judgement rule. As compared with the prior sub-optimal algorithm, the method provided by the invention improves bit error rate performance of a relay receiving end well, and simultaneously achieves full diversity gain at the receiving end. Finally, the provided algorithm is subjected to simulation verification, and the result of simulation verification is consistent with theoretical analysis.

The invention relates to the technical field of laser communication, in particular to a signal processing and transmitting method suitable for FSO physical layer network coding. The invention aims atsolving the problem of large integer multiples of frequency offset in the prior art. The technical scheme of the invention is as follows: the method comprises the following steps: frequency offset estimation values of the signals A and the signals B are respectively solved by utilizing a preamble sequence designed in a staggered manner; a mean value of two estimated values is compensated for the superposed signal; due to the existence of A and B paths of residual frequency offsets, a common phase ej2pi delta can be regarded to be superposed between two adjacent OFDM symbols; wherein the size of the common phase is related to the size delta of the residual frequency offset, on the basis, a channel estimation value is obtained by utilizing the block pilot frequency, and all data block sequence superposed signals after the block pilot frequency can be further calculated by combining the common phase value brought by the frequency offset. The method is used for solving the problems of FSOsystem physical layer network coding frequency offset estimation and channel estimation.

The invention relates to a physical layer network coding method based on two-edge type low density parity check codes. The method comprises the following steps of S1, combining the TET-LPDC codes (Two-Edge Type Low Density Parity Check Codes) and PNC (Physical-layer Network Coding) codes according to a feature of a network layer coding model, and obtaining TET-LPDC-PNC codes through coding; S2, through combination of degree distribution of the TET-LPDC codes, decoding the TET-LPDC-PNC codes. According to the method, joint design is carried out on the two-edge type low density parity check codes and the physical-layer network coding codes; joint coding and decoding design is carried out on the TET-LPDC codes from an angle of a node according to a two-edge structure feature of the TET-LPDC codes; and for decoding, a serial likelihood information decoding mode is employed. According to the method, the coding and decoding complexity is greatly reduced.

The invention discloses a multi-AP cooperation based interference elimination method in a dense WLAN environment, mainly for solving the problems of mutual interference between access points and low system capacity in the prior art. The method comprises the following realization steps: in a communication process between a site and a current access point, other neighbor access points determining whether to send data, and if so, the neighbor access point directly sending the data and waiting for the site to replay a confirmation character; after the neighbor access point sends the data, transmitting the data to the current access point through a wired mode; the current access point, by use of a physical layer network encoding technology, performing demodulation mapping on received pollution signals and then determining an initial position of pollution by use of lead code correlation; and directly performing bit XOR after the initial position, and recovering original data from the pollution signals so as to eliminate interference signals. According to the invention, downlink service transmission of the neighbor access points and sites associated therewith is realized while the interference is eliminated, the system capacity is improved, and the method provided by the invention can be applied to a densely disposed WLAN environment.

The invention discloses a power distribution method of a two-way multi-hop network based on physical layer network coding, which is characterized by comprising the following steps: S1, establishing a two-way multi-hop network with N nodes; S2, utilizing a Frisk formula (the formula is shown in the specification) to calculate propagation loss of each link; S3, calculating a system parameter w according to a formula (the formula is shown in the specification); S4, setting the total transmitting power of a system as PT; and S5, according to formulas (the formulas are shown in the specification),determining the transmitting power PN of each node. The power distribution method has the beneficial effects that due to the adoption of the method, the optimum transmitting power value of each node can be obtained, the nodes in the network carries out power control according to the obtained optimum transmitting power value, and under the condition that the total power of the system is constant, theinterrupt probability of the system can be minimum, so that the stability and the reliability of the system are improved.