WO2011038526A1

WO2011038526A1 - Method and device for relaying

Info

Publication number: WO2011038526A1
Application number: PCT/CN2009/001104
Authority: WO
Inventors: 李纪; 胡中骥
Original assignee: 上海贝尔股份有限公司; 阿尔卡特朗讯
Priority date: 2009-09-29
Filing date: 2009-09-29
Publication date: 2011-04-07
Also published as: CN102474340A; CN102474340B

Abstract

A method and device for relaying are provided. The method includes the following steps: the bit probability ratios of every encoded bit in the packets from multiple mobile terminals are softly combined to generate soft network encoding packet information; channel decoding is performed for the soft network encoding packet information to obtain network encoding packet; channel encoding and modulation are performed for the network encoding packet; the modulated network encoding packet is sent to base station. Application of the method and device can implement signal relaying with high resource utilization efficiency, and save nearly half operation complexity in relay device.

Description

Relay method and device thereof

The present invention relates to the field of wireless transmission, and in particular to a relay method and device thereof. Background technique

In LTE-Advanced, trunking is considered an important technology to support high capacity and high coverage. In the uplink, a relay device usually needs to forward information for multiple mobile terminals (UEs), and in a conventional relay device, it is forwarded in a UE-by-UE manner. When the amount of served UEs increases, in a Time Division Multiplexing (TDM) system, forwarding by UE will result in a long delay, while in a Frequency Division Multiplexing (FDM) system, more frequency resources are needed for forwarding.

At the same time, for DF (decoding and forwarding) relay, the packet needs to be decoded and re-coded UE by UE, and the channel decoder and channel coder become the main complexity of the relay side.

Therefore, a more efficient relay forwarding method is needed to overcome the above problems. Summary of the invention

Embodiments of the present invention propose a relay method and apparatus therefor.

According to an aspect of an embodiment of the present invention, a relay method is provided, including: soft combining a bit likelihood of each coded bit in a packet from a plurality of mobile terminals to generate soft network coded packet information; The soft network encodes the packet information for channel decoding to obtain a network coded packet; performs channel coding and modulation on the network coded packet; and transmits the modulated network coded packet to the base station.

According to another aspect of an embodiment of the present invention, a relay signal processing method is provided, comprising: softening a first bit likelihood of each coded bit from a plurality of mobile terminals and a packet from a relay device Combining, generating a second bit likelihood of each coded bit of each of the mobile terminal from the plurality of mobile terminals, wherein the packet from the relay device is the relay device pair from the a network coded packet obtained by soft combining the packets of the plurality of mobile terminals; performing channel decoding on the second bit likelihood to obtain a packet from each of the plurality of mobile terminals.

According to another aspect of an embodiment of the present invention, a relay device is provided, including: a merging unit, configured to soft combine a bit likelihood of each coded bit in a packet from a plurality of mobile terminals to generate soft a network coding packet information, a decoding unit, configured to perform channel decoding on the soft network coding packet information, to obtain a network coding packet, a coding unit, configured to perform channel coding on the network coding packet, and a modulation unit, configured to perform channel coding The subsequent network coded packet is modulated; the first sending unit is configured to send the modulated network coded packet to the base station.

According to another aspect of an embodiment of the present invention, a base station is provided, comprising: a signal combining unit for first bit likelihood of coding bits for each of a plurality of mobile terminals and packets from a relay device Performing soft combining to generate a second bit likelihood of each coded bit of each of the mobile terminals from the plurality of mobile terminals, wherein the packet from the relay device is from the relay device pair a network coding packet obtained by soft combining the packets of the plurality of mobile terminals; a channel decoding unit, configured to perform channel decoding on the second bit likelihood, to obtain a packet from each of the plurality of mobile terminals .

According to still another aspect of an embodiment of the present invention, a communication system is provided, including the base station, the relay, and the plurality of mobile terminals described above.

Based on the above technical solution, the implementation of the present invention improves the resource utilization of the signal relay due to the transmission of two copies of data on one system resource. Moreover, on the relay device, the soft-combined received signal requires only half of the channel decoding and re-channel coding operations. Since the channel decoder and the channel coder are the main complexity of the relay side, the relay method of the present invention can save nearly half of the computational complexity with respect to the general decoding and forwarding relay. DRAWINGS

The advantages of the present invention will become readily apparent from the following description in conjunction with the drawings in which:

1 shows a schematic diagram of a communication system in accordance with an embodiment of the present invention;

2 is a block diagram of the relay device shown in FIG. 1 according to an embodiment of the present invention; FIG. 3 is a block diagram showing the base station shown in FIG. 1 according to an embodiment of the present invention;

FIG. 4 is a flowchart showing processing on the relay device side according to an embodiment of the present invention; FIG.

FIG. 5 is a flowchart showing a process of a base station side according to an embodiment of the present invention; FIG.

Figure 6 shows a schematic diagram of the flow chart shown in Figure 5;

FIG. 7 shows an effect diagram of a relay method according to an embodiment of the present invention. Detailed ways The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, and the details and functions that are not necessary for the present invention are omitted in the description to avoid confusion of the understanding of the present invention.

In an embodiment of the present invention, a wireless communication system is proposed. As shown in Fig. 1, the system includes a relay device, a base station, and a plurality of mobile terminals (UEs) described below.

A relay device is also proposed. As shown in FIG. 2, the base station includes a merging unit 230 for soft combining bit likelihood of each coded bit in a packet from a plurality of mobile terminals to generate a soft network coding. a decoding unit 240, configured to perform channel decoding on the soft network encoded packet information to obtain a network encoded packet; an encoding unit 260, configured to perform channel coding on the network encoded packet; and a modulating unit 270, configured to encode the channel The network coding packet is modulated; the first sending unit 280 is configured to send the modulated network coded packet to the base station.

The relay device further includes a demodulation unit 220 for demodulating packets from the plurality of mobile terminals to obtain a bit likelihood of each of the coded bits in each of the packets.

The relay device further includes a control unit 250, configured to determine whether the channel decoding performed on the soft network encoded packet information is correct, and if the determination result is correct, the control encoding unit 260 re-channelizes the channel-decoded soft network encoded packet information. .

The relay device also includes a first receiving unit 210 for receiving packet signals from a plurality of mobile terminals. A base station is also proposed. As shown in FIG. 3, the base station includes a signal combining unit 230 for performing a first bit likelihood ratio for each of the coded bits from the plurality of mobile terminals and the packets from the relay device. Soft combining, generating a second bit likelihood of each coded bit of each of the mobile terminals from the plurality of mobile terminals, wherein the packet from the relay device is a relay device performing packets from the plurality of mobile terminals The network coding packet obtained by soft combining; the channel decoding unit 240 is configured to perform channel decoding on the second bit likelihood to obtain a packet from each of the plurality of mobile terminals.

The base station further includes a base station demodulation unit 220 for demodulating packets from a plurality of mobile terminals and from the relay device to obtain a first bit likelihood for each coded bit of each packet.

The base station also includes a first receiving unit 210 for receiving packet data from a plurality of mobile terminals and relay devices.

Although the base station and the relay device of the embodiment of the present invention have been described above in the form of separate functional modules, each of the components shown in FIGS. 2 to 4 can be implemented by a plurality of devices in practical applications, showing many The components can also be integrated in a single chip or a device in practical applications. The base station and the relay device may also include Any unit and device used for other purposes.

The functions of the base station and the relay device provided by the embodiments of the present invention will be further described below with reference to Figs. 4 and 5.

4 is a flow chart of a relay device side relay method. As shown in FIG. 4, first, in step 410, the first receiving unit 210 of the relay device receives packets from a plurality of UEs. Taking two UEs as an example, the packets received by the relay device are:

SS ₂ is the symbol transmitted by UE1 and UE2, respectively, and / 3⁄4 _R are the fading channel models of UE1 and UE2 to the relay device respectively, and ^^^^ is the independently distributed Gaussian white noise on these channels, and its square σ .

In step 420, the demodulation unit 220 of the relay device demodulates the received plurality of packets, respectively. Taking the first symbol 8 transmitted by UE1 as an example, first, the symbol likelihood calculated according to formula (3)

Where _Sli is the possible value of the symbol in the current modulation mode. For example, for QPSK, i=l~4. Then, calculate the bit likelihood (LLRb) of the j-bit in symbol 3 according to equation (4):

(4) where j, k is the number of coded bits that each symbol may contain, j, ^l,..., log ₂ (max(i)), for QPSK encoding, j, k=l, 2.

Similarly, the same processing is performed on the symbols received from UE2.

In step 430, the merging unit 230 of the relay device soft combines the likelihood ratios of the plurality of UEs obtained by the demodulation to generate soft network coding packet information, so that the received signal is P1 ® P2, and Not P1 and P2.

Assuming that the received packet is P _NC = P1 © P2, then a packet network coding in bits P _NC having b _NC As shown in Table 1 possibilities, which is a packet P! Is a coded bit, b2 is in the packet P 1 ^ ₂ corresponding to the coded bits, encoding means for encoding a network packet from a network of a plurality of sources The network coded bits refer to the bits after network coding.

Table 1 Various possible values of the received bits

b, ^NC

0 0 0

0 1 1

1 0 1

1 1 0

, b _NC likelihood ratio is shown in formula (5), where P1 and P2 are independent:

(5) Divide the numerator and denominator by ^! ^Two. ^^!^:. ^ , get the formula (6):

LLR{b _NC )-lo _{gl + e LLR(b])+LLR[b2))} (6) It can be seen that, by equation (6), when P1 and P2 are received, the received packet is inferred to be Bit likelihood for P1 ® P2. In the embodiment of the present invention, the bit likelihoods of P1 and P2 have been respectively obtained according to the formula (3) and the formula (4), and constructed according to the formula (6), the bit likelihood of P1 © P2 can be obtained. Representing P1 ©P2, gp, applying equation (6) bit by bit to P1 and P2, the generated bit likelihood sequence represents the signal equivalent to PI ® P2.

In this step, if the lengths of the symbols are inconsistent, you can fill all the zeros or all 1s at the end of the shorter symbol to reach the length of the longest symbol.

In step 440, the decoding unit 240 of the relay device performs channel decoding on the soft network encoded packet information. This step is to perform channel decoding on ( _e ). As described above, in the case that the relay device receives correctly, the decoded packet obtained should be P1®P2.

In step 450, the control unit 250 of the relay device determines whether channel decoding has been correctly performed. In this step, the CRC check code can be used to determine whether the channel decoding is correct. Since the network coding is linear operation, the network-encoded CRC check bit can still be used to judge whether the decoding is correct or not. Of course, those skilled in the art should know that the manner of determining whether the channel decoding is correct is not limited to the CRC check code used in the present embodiment. If the channel decoding is not correct, in step 460, the packet obtained by the channel decoding is relayed according to a conventional method, for example, in the AF (Amplified Forwarding) relay, the packet obtained by decoding the channel; P1 and P2 are amplified and Forward.

If the channel decoding is correct, in step 470, the encoding unit 260 of the relay device re-channel encodes the decoded network encoded packet, and modulates by the modulator 270 in step 480, and passes the first transmitting unit in step 490. 280 to send.

In the above technical solution, those skilled in the art may know that the demodulation unit 220 and the modulation unit 270 may be implemented by a single chip, and the decoding unit 240 and the coding unit 260 may also be implemented by a single chip. In the step preceding step 490, the step of reproducing and/or amplifying the received packet may also be included.

Figure 5 is a flow chart of the processing performed by the base station side for the packet signal relayed according to the method of Figure 4. The processing on the base station side will be described below with reference to Fig. 5.

In step 510, the second receiving unit 310 of the base station receives signals from different UEs and relay devices, respectively. As in the present embodiment, it is received from UE1 and UE2, respectively:

Received from the relay device -

^ , B 2, B · ^3 + 3⁄4B (g) where S^ S^n S ₃ are symbols transmitted from UE1, UE2 and the relay device, respectively, /3⁄4, ₂ and _B are UE1, UE2 and the relay apparatus to the base station of the fading channel model, _¾ ,, _¾, ₂ and _¾B are Gaussians with those independent white noise distribution channels incorporated variance σ ^2, and wherein, at the relay device is a _{S. 3} S ^BS ₂ performs soft combining and re-channel coding the corresponding modulation symbols in the network coded packet.

In step 520, the base station demodulation unit 320 pairs are received from UE1, UE2 and the relay device to the packet Pl, P2 and P3 (S,> S ₂ and S ₃ respectively, Pl, P2, and P3 an example of symbol, Pl, P2, and P3 each contain a large number of transmission symbols. Perform a demodulation operation performed at step 420, such as at the relay device, to obtain the first coded bit likelihoods ^^) of P1, P2, and P3, respectively. (6 _NC ) sequence.

In step 530, the signal combiner 330 of the base station soft combines the likelihoods of the obtained P1, P2, and P3.

Taking the second bit likelihood ratio of P1 in the example, after receiving the signals from UE1, UE2 and the relay device respectively, according to Table 1, the second bit likelihood ratio of 6 in P1 is calculated as follows ^^^ ) : _LlR{b ) _ _{)og N} c I _c = 1] , = b, =0) + P[y _N c I = ]P(b, = l)P{b ₂ = l)

Pbnc I _c = 0]p(b _t = 0)p(b ₂ = 0)+P[y _NC | 6 _NC = l]P(i», = 0)p{b ₂ = 1)

(9) where b!, b _2, and b _NC are an example bit in P1, P2, and P3, respectively, without loss of generality, and the first coded bit in the packet may be used as an example bit.

Divide by the numerator and denominator of equation (9)

Get the likelihood of soft combining -

_L l _R i _b ) ₌ exp(ziR(3⁄4 _NC ) + (6,))+ exp(Z _a (3⁄4,)+ L _a (b ₂ ))

1 + exp ( R(6 _NC )". ( )

= _L ( _b ) ₊

One. ,

₍₁₀₎ wherein, R & lt _(e;) is the first bit in the likelihood P _NC _e can be calculated at step 520,) _{= log} ^ L ^ means a priori information (in the present embodiment, _n = l, 2), if it is here. , ^{n/ 5} P(b„ = θ) has not been received before, assuming that the source has an equal probability, therefore, p(b _n =l)=P(b _n =0), L» . Since b has been received , and b ₂ , replace the a priori information with the posterior probability Rfe ) and ZR( ) derived before. Therefore, ili bj becomes:

According to the approximation theory of log ( _e ^fl + _e ^ft )« _max (i ), the formula (11) can be simplified as follows to reduce the amount of calculation:

LLR {b ) « LLR (6, ) + max (LLR (3⁄4 _c ), LLR (3⁄4))- max (0, LLR (b _NC ) + LLR (b ₂ ))

(12)

The second bit likelihood JZi?() in P2 can also be generated by a similar method.

Subsequently, in step 540, the channel decoder 340 of the base station performs channel decoding on the second bit likelihood of each of the coded bits in the soft combined signal to obtain respective information bits in the packet P1 and the packet P2, respectively.

FIG. 6 shows a brief flow of performing soft combining processing on the base station side, wherein the processing of step 610 and step 620 is the processing of P3 in step 520. For the sake of brevity, the processing of P1 and P2 is omitted in FIG. Step 630 is the same as step 530, and step 640 is the same as step 540. As shown in Figure 6, in order to use the network coding information for soft combining, only one additional preprocessing described in equation (12) needs to be added, that is, Figure 6 In step 630, when the max-log-MAP algorithm (approximation algorithm) is employed, the preprocessing has a very low complexity.

Next, the technical effects of the technical solutions described in the embodiments of the present invention will be described based on the simulation results. In this simulation, the channel is assumed to be a Rayleigh channel, and the Rayleigh fading has a unit variance that is interfered by Gaussian white noise. UE1 and UE2 have the same channel state, the link between the relay device-base station has the same channel state as the link between the UE-base station, and the link quality between the UE-relay devices is higher than that of the UE-base station. The quality of the link is good. The channel coding uses a UMTS l/3 Turbo code with a length of 3456 bits and the modulation type is QPSK.

Fig. 7 shows the simulation results. In Fig. 7, the horizontal axis is the signal-to-noise ratio (E _b /No) and the vertical axis is the error grouping ratio (PER). As shown in FIG. 7, as the UE-relay link becomes better, the technical solution proposed by the embodiment of the present invention has gradual performance compared to the non-relay mode, and the performance approaches the traditional XOR network coding. Following. Since the purpose of the relay layout is to improve the performance of the cell edge user, it is a very common case that the UE-relay link is better than the UE-base station link by several _dB . In such a case, the soft network coding relay can be used instead of the XOR relay in the embodiment of the present invention to achieve XOR relay performance and further reduce computational complexity. At the same time, compared with the traditional DF relay, the technical solution proposed by the embodiment of the present invention saves 50% of the resources by merging the information originally sent in the two resources into one resource. Transmit power. Moreover, on the relay station, since the soft-combined soft network coding information requires only half of the channel decoding and re-channel coding operation, the soft network coding method proposed by the present invention can save nearly half of the computational complexity on the relay station.

The technical solution proposed in the embodiment of the present invention is not limited by the wireless transmission mode, and is different in frequency division, time division, space division or code division mode, and the difference is only in the resources used for transmission, and the person skilled in the art may The wireless transmission method easily uses the embodiments of the present invention for various wireless transmission systems.

Although only two mobile terminals are used for the sake of brevity in the embodiment of the present invention, those skilled in the art should readily recognize that the technique in the embodiments of the present invention can also be implemented using a plurality of two mobile terminals. Program. In a specific implementation, UE1 and/or UE2 in the embodiment of the present invention may also be replaced by another one/two relays.

Those skilled in the art will readily recognize that the different steps of the above methods can be implemented by a programmed computer. Herein, some embodiments also include a machine readable or computer readable program storage device (eg, a digital data storage medium) and encoding machine executable or computer executable program instructions, wherein the instructions perform some of the above methods or All steps. For example, the program storage device can be a digital memory, a magnetic memory Storage media (such as disk and tape), hardware or optically readable digital data storage media. Embodiments also include a programming computer that performs the steps of the above method.

The description and drawings merely illustrate the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various structures, which are not specifically described or illustrated herein, but are intended to be within the spirit and scope of the invention. In addition, all of the examples mentioned herein are explicitly used primarily for teaching purposes to assist the reader in understanding the principles of the present invention and the concepts promoted by the inventors, and should be construed as not to the specific examples. And conditional restrictions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as the specific examples thereof,

The above description is only used to implement the embodiments of the present invention, and those skilled in the art should understand that any modifications or partial substitutions without departing from the scope of the present invention should fall within the scope defined by the claims of the present invention. The scope of the invention should be determined by the scope of the claims.

Claims

1. A relay method, comprising:

Soft combining the bit likelihoods of each of the coded bits in the packets from the plurality of mobile terminals to generate soft network coded packet information;

Performing channel decoding on the soft network coding packet information to obtain a network coding packet;

Channel coding and modulating the network coded packet;

The modulated network coding right packet is transmitted to the base station.

2. The relay method according to claim 1, further comprising demodulating packets from the plurality of mobile terminals to obtain a bit likelihood of each of the coded bits in each of the packets.

3. The relay method according to claim 1, wherein the demodulating the packets from the plurality of mobile terminals is:

Calculating a symbol likelihood of each symbol of each of the packets from the plurality of mobile terminals; calculating a bit likelihood of each of the coded bits in each of the symbols based on the calculated symbol likelihood of each symbol rate.

4. The relay method according to claim 1, further comprising:

Determining whether the channel decoding performed on the soft network coded packet information is correct. If the determination result is correct, channel coding the network coded packet obtained after the channel decoding is performed, and if the determination result is incorrect, performing an amplification and forwarding relay scheme.

5. A method for processing a relay signal, comprising:

Soft combining the first bit likelihoods of each of the plurality of mobile terminals and the packets from the relay device to generate each coded bit of each of the plurality of mobile terminals a second bit likelihood ratio, wherein the packet from the relay device is a network coded packet obtained by the relay device soft combining the packets from the plurality of mobile terminals;

The second bit likelihood is signal-decoded to obtain packets from each of the plurality of mobile terminals.

6. The method of processing a relay signal according to claim 5, further comprising:

The packets from the plurality of mobile terminals and from the relay device are demodulated to obtain a first bit likelihood of each of the coded bits of each packet.

7. A relay device, comprising:

a merging unit, configured to soft combine the bit likelihoods of each of the coded bits from the plurality of mobile terminals to generate soft network coded packet information;

a decoding unit, configured to perform channel decoding on the soft network coded packet information, to obtain a network coded packet, and a coding unit, configured to perform channel coding on the network coded packet;

a modulating unit, configured to modulate the channel coded network coded packet;

The first sending unit is configured to send the modulated network coded packet to the base station.

8. The relay device according to claim 7, further comprising a demodulating unit configured to demodulate packets from the plurality of mobile terminals to obtain a bit likelihood ratio of each of the coded bits in each of the packets.

9. The relay device of claim 7, further comprising:

And a control unit, configured to determine whether channel decoding performed on the soft network encoded packet information is correct, and if the determination result is correct, the control coding unit re-channel-encodes the channel-decoded soft network encoded packet information.

10. A base station, comprising: a signal combining unit, configured to soft combine a first bit likelihood of each coded bit from a plurality of mobile terminals and a packet from a relay device to generate the plurality of a second bit likelihood of each coded bit of each mobile terminal in a packet of the mobile terminal, wherein the packet from the relay device is the relay device that softens packets from the plurality of mobile terminals Network coded packets obtained by combining;

And a channel decoding unit, configured to perform channel decoding on the second bit likelihood to obtain a packet from each of the plurality of mobile terminals.

11. The base station according to claim 10, further comprising:

And a base station demodulation unit, configured to demodulate packets from the plurality of mobile terminals and from the relay device to obtain a first bit likelihood of each of the coded bits of each packet.

A communication system comprising the relay according to any one of claims 7 to 9, the base station according to claim 10 or 11, and a plurality of mobile terminals.