CN101102296B - Method for realizing data flow multiplexing and multi-carrier communication system - Google Patents

Abstract

The key point of the invention is: the subcarriers correlated to same base node under the logical channel node allocated for the data to be transmitted by base station are discontinuously set in the entire sub-band under the physical frame; using said subcarriers to carry the data stream and to make data transmission. By the invention, the actual channel quality can make better fitting to the channel quality fed back during sub-band scheduling such that even if the user's data is transmitted in one base node, the user can also get better frequency diversity so as to improve the transmission performance of low rate users.

Description

Method for realizing data stream multiplexing and multi-carrier communication system

technical field

The invention relates to the field of communication, in particular to the multiplexing technology of data streams.

Background technique

The multi-carrier transmission technology is to decompose the data stream into several independent sub-data streams, so that each sub-data stream has a relatively low bit rate, and then use the low-rate multi-state symbols formed by the low bit rate to modulate the corresponding sub-carriers , forming multiple low-rate symbols sent in parallel. In recent years, multi-carrier transmission technology represented by OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) has attracted widespread attention. OFDM divides the frequency spectrum into many subcarriers, each modulated with a lower data rate. By assigning different subcarriers to different users, OFDMA (Orthogonal Frequency Division Multi Access, Orthogonal Frequency Division Multiple Access) can be realized. Each narrowband subcarrier adopts a different modulation method, such as QAM (Quarduture Amplitude Modulation, 16-quadrature amplitude modulation), 64-QAM, etc.

The OFDMA system takes the coded data to be transmitted as frequency domain information, modulates it into a time domain signal, and transmits it on the channel, and performs reverse process demodulation at the receiving end. The modulation and demodulation of the OFDMA system can be replaced by IDFT (Inverse Discrete Fourier Transform, Inverse Discrete Fourier Transform) and DFT (Discrete Fourier Transform, Discrete Fourier Transform) respectively: at the sending end, through N-point IDFT operations, the frequency domain data The symbols are transformed into time-domain data symbols, and after being modulated by the carrier, they are sent to the channel. At the receiving end, the received signal is subjected to coherent demodulation, and then the baseband signal is subjected to N-point DFT operation to obtain the transmitted data symbols. In practical applications, IDFT/DFT is implemented using IFFT (Inverse Fast Fourier Transform, Inverse Fast Fourier Transform) and FFT (Fast Fourier Transform, Fast Fourier Transform). The adoption of FFT technology greatly reduces the complexity of the OFDMA system, coupled with high-performance information processing devices, such as PLD (programmable Logic Device, programmable logic device), DSP (Digital Signal Processor, digital signal processor), μP (Micro The development and application of Processor (microprocessor), etc., make the realization of OFDMA system easier.

When using the OFDM system or the OFDMA system to transmit data streams, it is necessary to multiplex the data streams of multiple users into one physical frame for simultaneous transmission.

The prior art related to the present invention provides a method for transmitting data streams using data stream multiplexing technology, and its implementation process is as follows:

First, the base station assigns different logical channel nodes to different data streams to be sent according to information such as the user's sub-band channel quality. Then it is processed by the transmitter and receiver as shown in Figure 1: after the transmitter encodes/modulates the data packets in the data stream to be sent, the corresponding data symbols are obtained at the physical layer; and then according to the distribution of the base station The logical channel node modulates the obtained data symbol onto the subcarrier associated with the base node under the logical channel node, that is, multiplexes the obtained data symbol on the associated physical channel, so that The transmitter uses the physical channel associated with the base node under the logical channel node to carry the data packet of the data stream to be sent; secondly, it undergoes multi-carrier modulation processing, and finally sends it out through the antenna.

At the receiving end, after multi-carrier demodulation of the signal received by the antenna, the data symbols on the subcarriers associated with the base node under the channel node assigned to the user are extracted, and then the extracted data symbols are demodulated /Decoding processing, and finally recover the data packet.

The implementation of the process of multiplexing the resulting data symbols on the associated physical channel involved in the above transmission process is as follows:

The transmitter equally divides the subcarriers of the entire frequency band of the system used to transmit data packets into n subbands, wherein each subband consists of Ns consecutive subcarriers. The Ns subcarriers are equally divided into Ng groups in each subband, and each group consists of Nb=Ns/Ng subcarriers. Suppose a physical frame contains Nf OFDM symbols. Consecutive Nb subcarriers and consecutive Nf OFDM symbols form a physical channel resource block, and each subband contains Ng physical channel resource blocks, labeled 0,..., Ng-1, then the entire frequency band includes n*Ng Physical channel resource blocks.

The logical channel adopts a binary tree structure, and the root node at the top represents the channel resources of the entire frequency band. Each node has two child nodes. The bottom layer has n*Ng leaf nodes, which are called base nodes. A subtree with Nb base nodes in each binary tree corresponds to a subband.

Frequency division multiplexing is used to multiplex the base nodes under the subtree into the subband corresponding to the subtree in a physical frame, that is, each base node is associated with a physical channel resource block in the subband, It can be seen from FIG. 2 that the first base node on the left side of FIG. 2 is associated with physical channel resource block 0 (the shaded part of the slash) in the first physical frame. In different physical frames, each base node is associated with different physical channel resource blocks in the subband corresponding to the base node.

It can be seen from the technical solutions of the prior art that in the process of mapping logical channels to physical channels, the physical channel resource blocks in each physical frame to which each base node is mapped consist of consecutive Nb subcarriers, so the The channel quality of physical channel resource blocks will not change much within a coherent bandwidth, and the subband is composed of multiple physical channel resource blocks, which are much larger than the coherent bandwidth. The channel quality of each physical channel resource block is different, so If frequency selective scheduling is performed in units of subbands, it is easy to cause the quality of the channel fed back by the scheduled user to be inconsistent with the actual channel quality of data transmission, especially when the transmission rate of user data is low, such as only one physical channel resource is required When data is transmitted in blocks, the frequency-selective scheduling method based on sub-bands cannot enable users to obtain frequency-selective gains.

Contents of the invention

The present invention provides a data stream multiplexing method and a multi-carrier communication system to solve the problem in the prior art that the physical channel resource block in each physical frame to which each base node is mapped consists of consecutive Nb subcarriers , leading to the problem that when the transmission rate of user data is low, the method of frequency selective scheduling in units of subbands cannot enable users to obtain frequency selective gain.

The present invention realizes through following technical scheme:

The present invention provides a method for realizing data stream multiplexing, which includes:

Divide the subcarriers associated with the same base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts, and use a certain number of physical channel resource blocks as intervals to divide each subcarrier at equal intervals and discontinuously set in different physical channel resource blocks in the entire subband under the physical frame;

The data stream is carried and transmitted based on the subcarrier.

Preferably, the method also includes:

The base station allocates a corresponding logical channel node to the data stream to be sent by the user according to the sub-band channel quality information measured by the user.

Preferably, when different physical frames are used to transmit user data, a certain number of physical channel resource blocks are used as intervals, and each subcarrier is discontinuously set at different physical channel resource blocks in the entire subband under the physical frame process, including:

At intervals of a certain number of physical channel resource blocks, discontinuously setting each subcarrier at equal intervals in different physical channel resource blocks in the entire subband under the first physical frame;

And in other physical frames, discontinuously set each subcarrier in different physical channel resource blocks in the entire subband under each physical frame according to frequency hopping;

or,

At intervals of a certain number of physical channel resource blocks, discontinuously setting each subcarrier at equal intervals in different physical channel resource blocks in the entire subband under the first physical frame;

And in other physical frames, each subcarrier is discontinuously set in the physical channel resource block corresponding to the first physical frame.

Preferably, the method also includes:

Different base nodes allocated by the base station for different data streams are multiplexed to subcarriers in different physical channel resource blocks in the same subband in the same physical frame associated with the base nodes in a frequency division multiplexing manner.

A multi-carrier communication system, including a transmitting end and a receiving end, wherein:

The sending end includes a subcarrier mapping unit, which is used to divide the subcarriers associated with the same base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts, and use a certain number of physical channel resources The block is an interval, and each subcarrier is set discontinuously at equal intervals in different physical channel resource blocks in the entire subband under the physical frame;

and modulating the data symbols obtained after coding and modulation onto the subcarriers;

Wherein, the subcarrier mapping unit includes a grouping unit and a setting unit;

The grouping unit is configured to divide the subcarriers associated with each base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts;

The setting unit is configured to discontinuously set each subcarrier divided by the grouping unit in different physical channel resource blocks in the entire subband under the physical frame at intervals of a certain number of physical channel resource blocks.

Preferably, when multiple physical frames are used to transmit data, the setting unit includes:

The second setting subunit is used to use a certain number of physical channel resource blocks as an interval to set each subcarrier divided by the grouping unit at equal intervals and discontinuously in different sub-bands in different physical frames by using frequency hopping. In a physical resource block;

Or, at intervals of a certain number of physical channel resource blocks, each subcarrier divided by the grouping unit is discontinuously set at equal intervals in corresponding physical resource blocks in the entire subband under different physical frames.

Preferably, the subcarrier mapping unit further includes:

A multiplexing unit, configured to multiplex different base nodes allocated by the base station for different data streams to different physical channel resource blocks in the same subband of the same physical frame associated with the base node by using frequency division multiplexing on the subcarriers in .

As can be seen from the specific scheme of the present invention described above, the present invention brings the following beneficial effects:

In the present invention, since the subcarriers associated with each base node are discontinuously within the entire subband, the actual channel quality of data transmission and the channel quality fed back during subband scheduling can be better matched, so that even if the user Data is only transmitted on one base node, which can also enable users to obtain better frequency diversity, thereby improving the transmission performance of low-rate users.

Description of drawings

Fig. 1 is the multi-carrier communication system that background technology provides;

FIG. 2 is a relationship diagram between a base node and a physical channel provided by the background technology;

Fig. 3 is the flowchart of the first embodiment provided by the present invention;

FIG. 4 is a relationship diagram between a base node and a physical channel in the first embodiment provided by the present invention;

Fig. 5 is a diagram of the relationship between the base node and the physical channel in the second embodiment provided by the present invention

FIG. 6 is another diagram of the relationship between the base node and the physical channel in the second embodiment provided by the present invention;

Fig. 7 is a working principle diagram of the third embodiment provided by the present invention;

Fig. 8 is a simulation performance curve after simulating the technical solutions of the present invention and the prior art.

Detailed ways

The first embodiment provided by the present invention is a method for data stream multiplexing, which is mainly aimed at the situation that a physical frame carries user data, and its implementation process is shown in Figure 3, specifically including the following steps:

Step 1: The base station assigns a corresponding logical channel node to the data stream to be sent by the user according to the sub-band channel quality information measured by the user.

The user measures the subband channel quality around it in real time or periodically, and reports the measured subband channel with the best quality to the base station, and the base station allocates the corresponding logical channel according to the subband channel quality information reported by the user The node is used to send the data stream to be sent to the user.

The logical channel allocated by the base station to the user generally adopts a binary tree structure. The root node on the top layer represents the channel resources of the entire frequency band, each node has two child nodes, and the bottom layer has n*Ng leaf nodes called base nodes. Each subtree with Nb base nodes corresponds to a subband.

Step 2, discontinuously setting the subcarriers associated with each base node under the logical channel node allocated by the base station for the data stream to be sent by the user within the entire subband under the physical frame.

In step 2, first divide the subcarriers associated with each base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts, and then discontinuously set each subcarrier in the physical frame in different physical channel resource blocks in the whole subband. When a physical frame is used to transmit user data, a certain number of physical channel resource blocks are used as intervals, and each subcarrier is discontinuously arranged in different physical resource blocks in the entire subband under the same physical frame at equal intervals. The specific implementation process is as follows:

First, the subcarriers of the entire frequency band are equally divided into n subbands. Each subband consists of Ns consecutive subcarriers. The Ns subcarriers are divided into Ng*Na groups in each subband, and each group is composed of Nb=Ns/(Ng*Na) subcarriers. It is assumed that a physical frame includes Nf OFDM symbols. Then consecutive Nb subcarriers and Nf consecutive OFDM symbols form a physical channel resource block. Each subband contains Ng*Na physical channel resource blocks, numbered 0, . . . , Ng*Na-1. The entire frequency band contains n*Ng*Na physical channel resource blocks.

It can be seen from step 1 that a subtree with Nb base nodes corresponds to a subband. In this way, each base node under the subtree is associated with which physical channel resource block in the subband corresponding to the subtree. The physical channel resource blocks associated with the same base node may be equally spaced in subbands at intervals of Ng-1 resource blocks.

Step 2 will be described in detail below with reference to Figure 4, taking the wireless OFDM system as an example:

Assuming that the frequency bandwidth of a certain wireless OFDM system is 20 MHz, it includes 2048 subcarriers, and a physical frame includes 8 OFDM symbols. The base station selects the bandwidth of the sub-band as 1.25 MHz according to the channel quality information of the sub-band reported by the user, that is, 128 sub-carriers, and Ns is 128. It can be seen that the entire frequency band of the system can be divided into 16 sub-bands, that is, 16 is used for n. It is assumed that the minimum granularity of physical channel resource allocation is 16 (subcarriers)*8 (OFDM symbols). That is, each base node is associated with 16 subcarriers in each frame, and Ng is 16. If taking the effect of frequency diversity into consideration and taking Na=4, each subband contains 16*4 physical resource blocks, numbered 0, . . . , 63. Each physical channel resource block includes b=Ns/(Ng*Na)=4 consecutive subcarriers. In this way, each base node is associated with 4 physical channel resource blocks. The physical channel resource blocks associated with each base node are equally spaced on the subbands at intervals of 15 resource blocks. For example, the physical channel resource block numbers related to the first base node may be taken as 0, 16, 32, and 48, as shown in the shaded part of the slash in the figure. The physical channel resource block numbers related to the second base node are 1, 17, 33, 49 and so on. Different base nodes use frequency division multiplexing in the same physical frame.

Step 3, carrying and transmitting the data stream based on the subcarrier.

The second embodiment provided by the present invention. It is another data stream multiplexing method. On the basis of the first embodiment, it adds a description of the situation where multiple physical frames carry the same data stream, including two cases:

In the first case, as shown in FIG. 5 , when different physical frames are used to transmit user data, the channel resource blocks associated with the same base node are different.

In this case, each subcarrier is discontinuously set at equal intervals in different physical channel resource blocks in the entire subband under the first physical frame at intervals of a certain number of physical channel resource blocks; In other physical frames, each subcarrier is discontinuously set in different physical channel resource blocks in the entire subband under each physical frame according to frequency hopping, that is, subcarriers carrying the same data stream in different physical frames The carrier has changed.

In the second case, as shown in Figure 6, when different physical frames are used to transmit user data, the channel resource blocks associated with the same base node are the same, that is, in different frames, the subcarriers carrying the same data stream are the same.

In this case, each subcarrier is discontinuously arranged at equal intervals in different physical channel resource blocks in the entire subband under the first physical frame at intervals of a certain number of physical channel resource blocks; and In other physical frames, each subcarrier is discontinuously set in corresponding physical channel resource blocks in the entire subband of each physical frame in the same setting manner as the first physical frame.

The third embodiment provided by the present invention is a multi-carrier communication system, the structure of which is shown in FIG. 7 , including a sending end and a receiving end.

Wherein the sending end includes a code modulation unit, a subcarrier mapping unit and a multi-carrier modulation unit. The subcarrier mapping unit includes a grouping unit, a setting unit and a multiplexing unit. The setting unit includes a first setting unit.

The receiving end includes a multi-carrier demodulation unit, a sub-carrier demapping unit and a decoding and demodulation unit.

After the base station allocates logical channel nodes for the data stream to be sent by the user according to the sub-band channel quality information reported by the user, the coding and modulation unit at the sending end performs coding and modulation processing on the data packets in the data stream to be sent by the user, Obtain corresponding data symbols, and transmit the data symbols to the subcarrier mapping unit;

The subcarrier mapping unit divides the subcarriers associated with each base node under the logical channel node allocated by the base station for the data stream to be sent by the base station into N equal parts through the grouping unit; then through the first setting subcarrier in the setting unit The unit discontinuously sets each subcarrier divided by the grouping unit in different physical channel resource blocks in the entire subband under the physical frame, and can use a certain number of physical channel resource blocks as an interval to divide each subcarrier divided by the grouping unit The component sub-carriers are discontinuously arranged at equal intervals in different physical resource blocks in the entire sub-band under the same physical frame. Then, the multiplexing unit multiplexes the different base nodes allocated by the base station for different data streams of multiple users to different physical channel resources in the same subband under the same physical frame associated with the base node by using frequency division multiplexing on the subcarriers in the block.

It is assumed that a data stream is allocated to one base node, and the subcarriers associated with the base node are subcarriers corresponding to resource blocks 0, 16, 32, and 48. Then the data symbols on the data packet are modulated to the subcarriers corresponding to resource blocks 0, 16, 32, and 48 and sent out. Different data streams are allocated to different base nodes, and subcarriers associated with each base node are multiplexed in the same physical frame by means of frequency division multiplexing.

The multi-carrier modulation unit modulates together the multiple sub-carriers mapped by the sub-carrier mapping unit, and sends out the data symbols carried by the multi-carrier through the antenna of the transmitting end.

At the receiving end, the multi-carrier demodulation unit first demodulates the signal received through the antenna, and then according to the assigned base node, the sub-carrier demapping unit extracts the data symbols on the associated sub-carriers, and then The extracted data symbols are sent to the decoding and demodulation unit for demodulation and decoding processing, and finally the data stream sent by the sending end is recovered.

The fourth embodiment provided by the present invention is a multi-carrier communication system when multiple physical frames are used to carry the same data stream. The difference between it and the third embodiment is that: in the subcarrier mapping unit of the third embodiment Then set the first setting subunit, but the second setting subunit, which is used to discontinuously set each subcarrier divided by the grouping unit in different physical resource blocks in the entire subband under different physical frames by means of frequency hopping or set each subcarrier divided by the grouping unit in a corresponding physical resource block in the entire subband under different physical frames. The rest are the same as the third embodiment provided by the present invention, and will not be described in detail here.

It can be seen from the specific implementation methods provided by the present invention above that, since the present invention sets the subcarriers associated with each base node discontinuously within the entire subband of the physical frame, the actual channel quality and subband scheduling of data transmission are guaranteed The channel quality of the time feedback can be better matched, so that even if the user data is only transmitted on one base node, better frequency diversity can be obtained, which is conducive to improving the performance of the communication system. Fig. 8 is the simulation performance of the technical solution provided by the present invention and the technical solution provided by the prior art obtained after simulation under the PB3 channel model, wherein No. 1 curve is the FER (frame error rate) curve of the prior art solution, 2 The numbered curve identifies the FER (frame error rate) curve of the technical solution of the present invention. It can be seen that when the FER is 0.01, the technology of the present invention has a gain of 6dB compared with the prior art.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (7)

1. A method for realizing data stream multiplexing, comprising: Divide the subcarriers associated with the same base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts, and use a certain number of physical channel resource blocks as intervals to divide each subcarrier at equal intervals and discontinuously set in different physical channel resource blocks in the entire subband under the physical frame; The data stream is carried and transmitted based on the subcarrier. 2. The method according to claim 1, further comprising: The base station allocates a corresponding logical channel node to the data stream to be sent by the user according to the sub-band channel quality information measured by the user. 3. The method according to claim 1, wherein when different physical frames are used to transmit user data, a certain number of physical channel resource blocks are used as intervals, and each subcarrier is discontinuously arranged at equal intervals under the physical frame The processes in different physical channel resource blocks in the entire subband, specifically include: At intervals of a certain number of physical channel resource blocks, each subcarrier is set at equal intervals and discontinuously in different physical channel resource blocks in the entire subband under the first physical frame; and in other physical frames, according to the jump In the frequency mode, each subcarrier is discontinuously set in different physical channel resource blocks in the entire subband under each physical frame; or, At intervals of a certain number of physical channel resource blocks, each subcarrier is discontinuously arranged in different physical channel resource blocks in the entire subband under the first physical frame; and in other physical frames, each The sub-carriers are discontinuously arranged in the physical channel resource blocks corresponding to the first physical frame. 4. The method according to claim 1, further comprising: Different base nodes allocated by the base station for different data streams are multiplexed to subcarriers in different physical channel resource blocks in the same subband in the same physical frame associated with the base nodes in a frequency division multiplexing manner. 5. A multi-carrier communication system, comprising a sending end and a receiving end, characterized in that: The sending end includes a subcarrier mapping unit, which is used to divide the subcarriers associated with the same base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts, and use a certain number of physical channel resources The block is an interval, and each subcarrier is discontinuously set at equal intervals in different physical channel resource blocks in the entire subband under the physical frame; and the data symbols obtained after encoding and modulation are modulated onto the subcarriers; Wherein, the subcarrier mapping unit includes a grouping unit and a setting unit; The grouping unit is configured to divide the subcarriers associated with each base node under the logical channel node allocated by the base station for the data stream to be sent by the user into N equal parts; The setting unit is configured to discontinuously set each subcarrier divided by the grouping unit in different physical channel resource blocks in the entire subband under the physical frame at intervals of a certain number of physical channel resource blocks. 6. The multi-carrier communication system according to claim 5, when using multiple physical frames to transmit data, it is characterized in that: The setting unit includes a second setting subunit, which is used to set each subcarrier divided by the grouping unit at equal intervals and discontinuously in different physical frames at intervals of a certain number of physical channel resource blocks by frequency hopping. In different physical resource blocks in the subband; or at intervals of a certain number of physical channel resource blocks, each subcarrier divided by the grouping unit is discontinuously set in the corresponding subcarriers in the entire subband under different physical frames at equal intervals in a physical resource block. 7. The multi-carrier communication system according to claim 5 or 6, characterized in that: The subcarrier mapping unit further includes a multiplexing unit, configured to multiplex different base nodes allocated by the base station for different data streams to the same subcarrier under the same physical frame associated with the base node by frequency division multiplexing. on subcarriers in different physical channel resource blocks within the band.

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