CN115361091B - Down mixed broadcast unicast transmission method based on multi-user superposition transmission technology - Google Patents

Abstract

The invention discloses a downlink hybrid broadcast and unicast transmission method based on multi-user superimposed transmission technology. The method comprises: a base station obtains channel state information of a broadcast service from a cell edge user, and determines a coding and modulation scheme of the broadcast service according to the channel state information ; The base station selects a hotspot service area in the cell, and selects a unicast service with suitable channel conditions from the hotspot service area and superimposes transmission with the broadcast service; the base station makes the unicast service non-orthogonal to the broadcast service multiplexing to obtain a composite service, and determine the coding and modulation scheme of the composite service according to the channel quality information fed back by the user of the unicast service, and replace the coding and modulation scheme of the broadcasting service with the coding and modulation scheme of the composite service. The present invention can provide additional unicast services for the system without affecting the coverage performance of broadcast services, and improve the overall transmission efficiency of unicast services.

Description

Downlink hybrid broadcast and unicast transmission method based on multi-user overlay transmission technology

technical field

The invention relates to the technical field of digital information transmission, in particular to a downlink hybrid broadcast unicast transmission method based on multi-user overlay transmission technology.

Background technique

Cellular communication networks are facing explosive growth in traffic demand, and multimedia services such as high-definition video account for a particularly significant proportion of it. Since video services often have the characteristics of high overlap between wide-area users, that is, a small number of popular content is requested by a large number of users at the same time, the traditional unicast transmission method will inevitably face the problems of insufficient bandwidth and network congestion, and the broadcast method is used to push The above content can effectively alleviate this problem. For this reason, in the Rel-17 version of 5G, 3GPP supports 5G NR (global 5G standard based on new air interface design based on OFDM) multimedia based on SC-PTM (Single Cell Point To Multiploint) technology. The broadcast multicast (MBS) system has been studied in order to realize the coverage of the broadcast service to the handheld terminal. However, it still faces some problems, such as inability to effectively support wide-area large tower broadcasting; in order to ensure deep coverage of cells, the spectrum efficiency of mobile broadcasting services is low; in terms of physical layer transmission technology, there is a lack of deep interleaving and coding and modulation are not oriented to multi-service broadcasting channels optimization.

Spectrum is an important strategic resource. In order to make full use of the 700M golden frequency band, it is very necessary to improve the spectrum efficiency of the 5G MBS system. Compared with orthogonal multiplexing, non-orthogonal multiplexing can significantly improve the spectrum efficiency of the system in asymmetric service scenarios, while the multiplexing of broadcast services and unicast services is obviously an asymmetric service scenario. Hybrid broadcast-unicast transmission based on non-orthogonal multiplexing has received extensive attention recently.

In related proposals of LTE, the downlink non-orthogonal multiplexing transmission based on superposition coding has been extensively studied, and it is called Multi-User Superposition Transmission (MUST) technology. MUST (Multiuser superposition transmission, multi-user superposition transmission) technology is divided into three categories. The first category is the direct superposition of QAM (Quadrature Amplitude Modulation) constellation symbols at the sending end; the second category is non-linear superposition with Gray mapping composite constellation diagram. ; The third category is based on the gray-mapped QAM composite constellation for flexible bit segmentation.

The existing hybrid broadcast-unicast transmission schemes based on non-orthogonal multiplexing all adopt the method of direct superposition at the sending end and SIC (Successive interference cancellation) at the receiving end. However, SIC will bring a large calculation burden and processing delay to unicast users. When the broadcast service adopts time-frequency interleaving, the delay will be more significant. And when there are multiple orthogonally multiplexed unicast services and non-orthogonal multiplexed broadcast services, each unicast user will face such a problem, which does not meet the low-latency requirements of 5G. When the receiving end adopts independent demapping and single-stage decoding (that is, without SIC), compared with nonlinear superposition, direct superposition will cause a large BICM capacity loss because the composite constellation diagram is not Gray mapping, so the composite constellation based on Gray mapping The non-linear superposition of constellation diagrams is more suitable for low-complexity and low-delay receiving schemes without SIC. At the same time, the existing solutions do not take into account the support of Adaptive Modulation and Coding (AMC) for unicast services. When unicast services are adaptive, how to ensure that the coverage of broadcast services is not affected is also a problem that needs to be considered.

Therefore, the prior art still needs to be improved and improved.

Contents of the invention

The technical problem to be solved by the present invention is to provide a downlink hybrid broadcast-unicast transmission method based on multi-user overlay transmission technology in view of the above-mentioned defects in the prior art.

In a first aspect, the present invention provides a downlink hybrid broadcast-unicast transmission method based on multi-user overlay transmission technology, wherein the method includes:

The base station obtains channel state information of the broadcast service from the cell edge user, and determines a coding and modulation scheme of the broadcast service according to the channel state information;

The base station selects a hotspot service area in the cell, and selects a unicast service with suitable channel conditions from the hotspot service area and superimposes transmission with the broadcast service;

The base station non-orthogonally multiplexes the unicast service and the broadcast service to obtain a composite service, and determines the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user, and uses the composite service The coding and modulation scheme of the broadcasting service replaces the coding and modulation scheme of the broadcasting service.

In an implementation manner, the base station acquires channel state information of broadcast services from cell edge users, and determines a coding and modulation scheme of broadcast services according to the channel state information, including:

The base station sends a channel state reference signal to the cell edge user;

The cell edge user performs channel estimation according to the channel state reference signal, and feeds back the signal state information of the broadcast service to the base station, where the channel state information includes a received signal-to-noise ratio;

The base station selects an appropriate broadcast service coding and modulation scheme according to the signal state information, and the broadcast service coding and modulation scheme includes an effective constellation mapping order and a channel coding code rate.

In an implementation manner, the base station selects a hotspot service area in the cell, and selects a unicast service with a suitable channel condition from the hotspot service area for superimposed transmission with the broadcast service, including:

The base station selects a hotspot service area in the cell;

The base station sorts the channel state information of the unicast service users in the selected hotspot service area according to the channel state information fed back by the unicast service users in the cell, and selects the unicast service with suitable channel conditions for superimposed transmission with the broadcast service.

In an implementation manner, the determining the coding and modulation scheme of the composite service according to the channel quality value fed back by the unicast service user includes:

The unicast service user periodically measures the channel quality information, and maps the channel quality information into a CQI value and reports it to the base station;

The base station selects a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, and uses the target coding and modulation scheme as the coding and modulation scheme of the composite service, and the composite The coding and modulation scheme of the service includes: the order of composite constellation mapping and the code rate of channel coding.

In an implementation manner, the base station selects a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, including:

The base station determines a received signal-to-noise ratio range corresponding to the CQI value according to the CQI value;

According to the received signal-to-noise ratio range, it is determined to select a target coding and modulation scheme corresponding to the received signal-to-noise ratio range among the preset coding and modulation schemes.

In one implementation, the method further includes:

The base station notifies the unicast service user of the coding and modulation scheme channel control information of the composite service.

In the second aspect, the embodiment of the present invention also provides a downlink hybrid broadcast-unicast transmission system based on multi-user superimposed transmission technology, wherein the system includes: a base station and a cell, and the base station includes:

The broadcast service analysis module is used to obtain the channel state information of the broadcast service from the cell edge users, and determine the coding and modulation scheme of the broadcast service according to the channel state information;

A unicast service determination module, configured to select a hotspot service area in the cell, and select a unicast service with suitable channel conditions from the hotspot service area for superimposed transmission with the broadcast service;

A coding and modulation scheme determination module, configured to non-orthogonally multiplex the unicast service and the broadcast service to obtain a composite service, and determine the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user , and replace the coding and modulation scheme of the broadcast service with the coding and modulation scheme of the composite service.

In an implementation manner, the broadcast service analysis module includes:

a signal sending unit, configured for the base station to send a channel state reference signal to a cell edge user;

The state receiving unit is used for the cell edge user to perform channel estimation according to the channel state reference signal, and to feed back the signal state information of the broadcast service to the base station, and the channel state information includes a received signal-to-noise ratio;

The scheme determining unit is used for the base station to select an appropriate broadcasting service coding and modulation scheme according to the signal state information, and the broadcasting service coding and modulation scheme includes an effective constellation mapping order and a channel coding code rate.

In an implementation manner, the unicast service determination module includes:

The base station selects a hotspot service area in the cell;

The base station sorts the channel state information of the unicast service users in the selected hotspot service area according to the channel state information fed back by the unicast service users in the cell, and selects the unicast service with suitable channel conditions for superimposed transmission with the broadcast service.

In an implementation manner, the coding and modulation scheme determination module includes:

The CQI value determination unit is used for unicast service users to periodically measure channel quality information, and map the channel quality information into a CQI value and report to the base station;

A scheme selection unit, configured for the base station to select a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, and use the target coding and modulation scheme as the coding of the composite service Modulation scheme, the coding and modulation scheme of the composite service includes: the order of composite constellation mapping and the channel coding code rate.

In an implementation manner, the scheme selection unit includes:

A signal-to-noise ratio range determination subunit, configured for the base station to determine a received signal-to-noise ratio range corresponding to the CQI value according to the CQI value;

The target scheme determining subunit is configured to determine a target coding and modulation scheme corresponding to the range of the receiving signal-to-noise ratio among the preset coding and modulation schemes according to the range of the receiving signal-to-noise ratio.

In an implementation manner, the base station further includes:

The information notifying module is used for notifying the unicast service user of the coding and modulation scheme channel control information of the composite service.

In the third aspect, the embodiment of the present invention also provides a base station. The base station includes a memory, a processor, and a downlink hybrid broadcast-unicast transmission program based on the multi-user overlay transmission technology that is stored in the memory and can run on the processor. The processor When executing the downlink hybrid broadcast and unicast transmission procedure based on the multi-user overlay transmission technology, the steps of the downlink hybrid broadcast and unicast transmission method based on the multi-user overlay transmission technology in any one of the above solutions are implemented.

Beneficial effects: Compared with the prior art, the present invention provides a downlink hybrid broadcast and unicast transmission method based on multi-user overlay transmission technology. First, the base station obtains the channel state information of the broadcast service from the cell edge users, and according to the The channel state information determines the broadcasting service coding and modulation scheme. Then, the base station selects a hotspot service area in the cell, and selects a unicast service with a suitable channel condition from the hotspot service area for superimposed transmission with the broadcast service. Finally, the base station non-orthogonally multiplexes the unicast service and the broadcast service to obtain a composite service, and determines the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user, and uses the The coding and modulation scheme of the composite service replaces the coding and modulation scheme of the broadcasting service. The base station of the present invention can adaptively adjust the coding and modulation scheme of the composite service according to the feedback of non-orthogonal multiplexed unicast users, and provide additional unicast services for the system without affecting the coverage performance of the broadcast service, thereby improving the unicast The overall transmission efficiency of broadcast services.

Description of drawings

FIG. 1 is a flow chart of a specific implementation of a downlink hybrid broadcast-unicast transmission method based on a multi-user overlay transmission technology provided by an embodiment of the present invention.

Figure 2 shows the channel capacity of different bits of Gray-256-QAM under the AWGN channel.

Fig. 3 is a schematic diagram of an equivalent composite constellation mapping group (16, 64, 256 order NU-QAM).

Fig. 4 is a schematic diagram of the channel capacity of the broadcasting service under different constellation mappings in the equivalent composite constellation mapping group.

Fig. 5 is a schematic diagram of channel capacity of unicast services under different constellation mappings in an equivalent composite constellation mapping group.

FIG. 6 is a schematic diagram of a constrained reachable capacity boundary of a constellation.

FIG. 7 is a schematic diagram of the present invention using the SFN architecture.

FIG. 8 is a functional schematic diagram of a downlink hybrid broadcast-unicast transmitter device based on a multi-user overlay transmission technology provided by an embodiment of the present invention.

Fig. 9 is a functional block diagram of a base station provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and effect of the present invention more clear and definite, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

This embodiment provides a downlink hybrid broadcast-unicast transmission method based on multi-user overlay transmission technology. First, the base station obtains channel state information of broadcast services from cell edge users, and determines a coding and modulation scheme of broadcast services according to the channel state information. Then, the base station selects a hotspot service area in the cell, and selects a unicast service with a suitable channel condition from the hotspot service area for superimposed transmission with the broadcast service. Finally, the base station non-orthogonally multiplexes the unicast service and the broadcast service to obtain a composite service, and determines the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user, and uses the The coding and modulation scheme of the composite service replaces the coding and modulation scheme of the broadcasting service. The base station in this embodiment can adaptively adjust the coding and modulation scheme of the composite service according to the feedback of the non-orthogonal multiplexed unicast users, and provide additional unicast services for the system without affecting the coverage performance of the broadcast service, improving the The overall transmission efficiency of unicast services.

exemplary method

During specific implementation, as shown in FIG. 1, the downlink hybrid broadcast and unicast transmission method based on the multi-user overlay transmission technology of this embodiment includes the following steps:

Step S100, the base station acquires channel state information of broadcast services from cell edge users, and determines a coding and modulation scheme for broadcast services according to the channel state information.

In this embodiment, the transmission mode of the broadcast service can be adjusted according to the channel state information of the broadcast service of the edge users of the cell. Therefore, the base station first obtains the channel state information of the broadcast service from the cell edge users, and then determines the channel state information according to the channel state information. The coding and modulation scheme of the broadcasting service, that is, the transmission mode of the broadcasting service is obtained. Compared with the traditional single-layer multimedia broadcasting system with a fixed transmission mode, the adjustment of the transmission mode in this embodiment can improve the spectrum efficiency of the broadcast channel.

In an implementation manner, the above step S100 specifically includes the following steps:

Step S101, the base station sends a channel state reference signal to the cell edge user;

Step S102, the cell edge user performs channel estimation according to the channel state reference signal, and feeds back the signal state information of the broadcast service to the base station, and the channel state information includes the received signal-to-noise ratio;

Step S103, the base station selects an appropriate broadcasting service coding and modulation scheme according to the signal state information, and the broadcasting service coding and modulation scheme includes effective constellation mapping order and channel coding rate.

Specifically, the base station first sends a channel state reference signal to the cell edge user, and then selects an appropriate broadcast service coding and modulation scheme according to the channel state information such as the received signal-to-noise ratio of the cell edge broadcast service, and the broadcast service coding and modulation scheme includes an equivalent constellation Mapping order and channel coding rate. The meaning of the equivalent constellation mapping order here is that if the composite constellation mapping order is M and carries Mb bits, where Mb1=log ₂ M1 bits are used for the transmission of the broadcasting service, then M1 is the equivalent of the broadcasting service Constellation mapping order.

When selecting a coding and modulation scheme for broadcasting services, for a fixed-mode multimedia broadcasting system, if the transmission mode is selected according to the worst channel condition in the covered area, the spectrum efficiency will be low and channel resources will be wasted. One solution is to select the appropriate transmission mode according to the channel conditions in the coverage area. For example, in rainy, snowy and windy weather, the channel conditions are poor, and the base station chooses the most robust transmission mode, that is, the combination of low-order constellation mapping and low coding rate; when the weather conditions are good, the channel conditions are good, and broadcast services in the coverage area If the terminal has a better receiving signal-to-noise ratio, the base station selects a combination of high-order equivalent constellation mapping and high coding rate.

The meaning of the equivalent constellation mapping order is that if the composite constellation mapping order is M and carries Mb bits, where Mb1=log ₂ M1 bits are used for the transmission of the broadcasting service, then M1 is the equivalent constellation mapping of the broadcasting service Order. A transmission mode of a broadcasting service, that is, an equivalent constellation mapping order and a code rate correspond to a set of equivalent composite constellation mapping groups. The equivalence here has two meanings. One is that these composite constellation maps use Mb1 bits for broadcasting services; the other is that the sum of mutual information of these composite constellation maps for broadcasting services Mb1 bits There is the same SNR threshold at the transmission rate of the mode. Therefore, any composite constellation mapping in the equivalent composite constellation mapping group is equivalent to the transmission of the broadcast service in the selected mode. The reason why it is necessary to design a group of equivalent composite constellation mapping groups of different orders for a broadcast service transmission mode is because when the broadcast service transmission mode is selected, the unicast service superimposed on the broadcast service has an adaptive selection code modulation scheme needs.

After the transmission mode of the broadcast service is selected, an M-order composite constellation map carrying Mb bits can be selected from the equivalent constellation mapping group corresponding to the transmission mode of the selected broadcast service according to the requirements of the unicast service. Different bits in the high-order composite constellation diagram often exhibit Unequal Error Protection (UEP) characteristics, that is, different bits have different reliability or transmission capabilities. Figure 2 shows the variation curve of the channel capacity of 8 bits in the Gray-256-QAM constellation mapping with the signal-to-noise ratio. It can be seen that the 8 bits present 4 different error protection capabilities. Since the reception threshold of the broadcast service is significantly lower than that of the unicast service, the most robust Mb1 bits among the Mb bits should be selected for the broadcast service. From the perspective of mutual information, the Mb1 bits with the largest bit channel capacity should be selected under the corresponding receiving signal-to-noise threshold. It is worth noting that, for the case of Mb1=2, the two bits that determine the quadrant position in the composite constellation diagram are often the most robust bits. As shown in Figure 2, bit 0 and bit 1 are the two bits that determine the quadrant in Gray-256-QAM, and these two bits are more reliable than other bits in the entire SNR range.

For example, due to bad weather and poor channel conditions in the covered cells during a certain period of time, the base station selects the most robust broadcast service transmission mode, that is, the equivalent constellation mapping order is 4, and the code rate is 1/2. At this time, an equivalent composite constellation mapping group is determined, and a composite constellation mapping diagram is selected according to the requirements of the superimposed unicast service. Then the two bits of the determined quadrant in the composite constellation diagram are used for broadcast service transmission, and the rest of the bits are used for superimposed unicast service transmission.

In order to correctly demodulate the broadcast service information at the broadcast service receiving end, the base station needs to inform the broadcast service terminal of the MCS of the composite service through control signaling, including the composite constellation map, the bit positions assigned to the broadcast service in the composite constellation map, and The channel coding rate of the broadcast service.

Step S200, the base station selects a hotspot service area in the cell, and selects a unicast service with a suitable channel condition from the hotspot service area and superimposes transmission on the broadcast service.

Specifically, the step S200 includes the following steps:

Step S201, the base station selects a hotspot service area in the cell;

Step S202, the base station sorts the channel state information of the unicast service users in the selected hotspot service area according to the channel state information fed back by the unicast service users in the cell, and selects a unicast service with suitable channel conditions to be superimposed on the broadcast service transmission.

Specifically, the base station in this embodiment first selects a hotspot service area in the cell, and unicast users in the hotspot service area have high demand for unicast traffic. The base station adjusts relevant parameters such as the transmitting antenna pattern to have higher antenna gain in the direction of the hotspot service area. In order to fully exploit the performance gain brought by superposition coding, the base station sorts the channel state information of unicast users in the selected hotspot service area, and selects the unicast service with suitable channel conditions to be superimposed with the original broadcast service for transmission without affecting the broadcast service coverage. Provide additional unicast transmission capability for the system under the premise.

Step S300, the base station non-orthogonally multiplexes the unicast service and the broadcast service to obtain a composite service, and determines the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user, and uses the obtained The coding and modulation scheme of the composite service replaces the coding and modulation scheme of the broadcasting service.

In an implementation manner, the above step S300 includes the following steps:

Step S301, the unicast service user periodically measures channel quality information, and maps the channel quality information into a CQI value and reports it to the base station;

Step S302, the base station selects a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, and uses the target coding and modulation scheme as the coding and modulation scheme of the composite service, The coding and modulation scheme of the composite service includes: the order of composite constellation mapping and the code rate of channel coding.

In existing cellular mobile communication networks, adaptive modulation and coding (AMC) is used for unicast services to match the link throughput with the time-varying channel characteristics, so that the BLER is lower than a certain threshold. In order to ensure the quality of service of unicast service users, the solution proposed in this embodiment also supports AMC. Specifically, the unicast service user periodically measures the downlink quality (that is, channel quality information), and maps the channel quality information into a CQI (Channel quality indicator, channel quality indicator) value and feeds it back to the base station. Each CQI value corresponds to a received signal-to-noise ratio range, and the base station determines the received signal-to-noise ratio range corresponding to the CQI value according to the CQI value. Then, according to the received SNR range, select the target coded modulation scheme corresponding to the received SNR range from the preset coded modulation schemes, and use it as the coded modulation scheme of the composite service, including the order of composite constellation mapping number and channel coding rate. Finally, the base station informs the unicast service user of the selected coding and modulation scheme of the composite service through channel control information.

Specifically, when the transmission mode of the broadcast service is determined (the switching frequency of the transmission mode of the broadcast service is generally much lower than the frequency of the AMC of the unicast service), there is a group of composite constellations with different orders, but equivalent to the current broadcast service mode. For unicast service selection. For example, when the broadcast service mode is selected to have an equivalent constellation mapping order of 4, a code rate of 5/6, and a receiving signal-to-noise ratio threshold of 5dB, an equivalent composite constellation mapping group that meets the requirements can be as shown in Figure 3 Composite constellation map.

Figure 4 shows the variation curve of the channel capacity of the broadcasting service with the signal-to-noise ratio under the several composite constellation diagrams described in Figure 3. It can be seen that for the selected broadcasting service transmission mode, these composite constellation maps are equal effective. Fig. 5 shows the change curve of the channel capacity of unicast service with the signal-to-noise ratio under several composite constellation diagrams described in Fig. 3. SNR range) to select the appropriate target coding modulation scheme. For example, when the signal-to-noise ratio range of unicast service users is 10-15dB, NU-16-QAM and a suitable coding rate should be selected; for example, when the SNR range of unicast service users is 25-30dB, the Select NU-256-QAM and an appropriate encoding rate.

This embodiment illustrates that the compound constellation obtained by nonlinearly superimposing the uniform QAM constellation in MUST-Type2 according to a certain power ratio has a large gap from the reachable capacity limit at some system operating points. Through the optimization of the compound constellation, it can be reduced This gap further improves the spectral efficiency of the system.

Assume that the equivalent constellation mapping order of the broadcast service is 4, the code rate is 1/2, the signal-to-noise ratio threshold is 5dB, and the received signal-to-noise ratio of the unicast service user is 15dB. Figure 6 plots the achievable capacity domains when different composite constellations are used (the capacity bounds for time-division multiplexing and Gaussian input are also given for comparison), and it can be seen that the composite The constellation diagram can provide a transmission rate of about 3.0 bit/symbol for unicast services at a receiving signal-to-noise ratio of 15 dB. However, using the APSK constellation diagram as a composite constellation map and performing certain optimizations under the transmission mode of the selected broadcast service and the receiving signal-to-noise ratio of the unicast service can provide a certain shaping gain and better multi-user superposition gain. Figure 6 also shows the achievable capacity when using the non-uniform APSK composite constellation mapping optimized for the current embodiment. It can be seen that the optimized composite constellation mapping can be unicast without affecting the broadcast service coverage. The service provides a higher transmission rate of about 3.2bit/symbol (when comparing the achievable capacity above, the receiver assumes that independent demapping and single-stage decoding are used).

In another implementation, this embodiment can also adopt a single frequency network (SFN) networking scheme. At this time, the broadcast services transmitted by base stations in different cells are completely the same signal, and each base station transmits the same signal in the same broadcast signal. The unicast services in the respective cells can be multiplexed, although from the perspective of the composite signal, the requirement of the same frequency and the same signal in the single frequency network is destroyed, but because the (equivalent) power of the basic layer broadcast service is often significantly higher than that of the multiplexed The (equivalent) power of the enhancement layer unicast service used, so it can be regarded as the noise introduced by the receiving end, so the present invention can be extended to the SFN architecture, as shown in Figure 7.

To sum up, the transmission mode of the broadcast service in this embodiment can be adjusted according to the channel conditions, that is, the broadcast service is selected according to the channel state information such as the received signal-to-noise ratio of the broadcast service fed back by the cell edge users. Compared with broadcasting systems with fixed transmission modes, higher spectral efficiency of broadcasting services can be obtained. In this embodiment, by adjusting the relevant parameters of the transmitting antenna pattern, the multiplexed unicast users can have a higher receiving signal-to-noise ratio, so as to obtain higher superposition coding gain. In this embodiment, the broadcast service and the unicast service are multiplexed in a non-linear superimposed manner, specifically performing bit division on a Gray-mapped composite constellation diagram, and assigning bit sub-channels with unequal error protection to channel conditions There is a big gap between broadcast and unicast services. Compared with the existing broadcast-unicast hybrid transmission scheme, this embodiment takes into account the support for unicast service AMC, that is, by introducing the concept of equivalent constellation mapping group, a set of equivalent constellation mapping groups is designed for each supported broadcast service transmission mode. The constellation mapping group can select composite constellation mapping according to the channel conditions of unicast users under the condition of being transparent to the broadcasting service.

exemplary system

Based on the above-mentioned embodiments, the present invention provides a downlink hybrid broadcast-unicast transmission system based on the multi-user overlay transmission technology, and the system includes: a base station and a cell. As shown in FIG. 8 , the base station includes: a broadcast service analysis module 10 , a unicast service determination module 20 and a coding and modulation scheme determination module 30 . Specifically, the broadcast service analysis module 10 is configured to obtain channel state information of broadcast services from cell edge users, and determine a coding and modulation scheme of broadcast services according to the channel state information. The unicast service determination module 20 is configured to select a hotspot service area in the cell, and select a unicast service with suitable channel conditions from the hotspot service area for superimposed transmission with the broadcast service. The coding and modulation scheme determining module 30 is configured to non-orthogonally multiplex the unicast service and the broadcast service to obtain a composite service, and determine the composite service according to the channel quality information fed back by the unicast service user. A coding and modulation scheme, and replacing the broadcasting service coding and modulation scheme with the coding and modulation scheme of the composite service.

In an implementation manner, the broadcast service analysis module includes:

a signal sending unit, configured for the base station to send a channel state reference signal to a cell edge user;

The state receiving unit is used for the cell edge user to perform channel estimation according to the channel state reference signal, and to feed back the signal state information of the broadcast service to the base station, and the channel state information includes a received signal-to-noise ratio;

The scheme determining unit is used for the base station to select an appropriate broadcasting service coding and modulation scheme according to the signal state information, and the broadcasting service coding and modulation scheme includes an effective constellation mapping order and a channel coding code rate.

In an implementation manner, the unicast service determination module includes:

The base station selects a hotspot service area in the cell;

The base station sorts the channel state information of the unicast service users in the selected hotspot service area according to the channel state information fed back by the unicast service users in the cell, and selects the unicast service with suitable channel conditions for superimposed transmission with the broadcast service.

In an implementation manner, the coding and modulation scheme determination module includes:

The CQI value determination unit is used for unicast service users to periodically measure channel quality information, and map the channel quality information into a CQI value and report to the base station;

A scheme selection unit, configured for the base station to select a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, and use the target coding and modulation scheme as the coding of the composite service Modulation scheme, the coding and modulation scheme of the composite service includes: the order of composite constellation mapping and the channel coding code rate.

In an implementation manner, the scheme selection unit includes:

A signal-to-noise ratio range determination subunit, configured for the base station to determine a received signal-to-noise ratio range corresponding to the CQI value according to the CQI value;

The target scheme determining subunit is configured to determine a target coding and modulation scheme corresponding to the range of the receiving signal-to-noise ratio among the preset coding and modulation schemes according to the range of the receiving signal-to-noise ratio.

In an implementation manner, the base station further includes:

The information notifying module is used for notifying the unicast service user of the coding and modulation scheme channel control information of the composite service.

The working principle of each module in the downlink hybrid broadcast-unicast transmission device based on the multi-user superimposed transmission technology in this embodiment is the same as that of each step in the above method embodiment, and will not be repeated here.

Based on the foregoing embodiments, the present invention further provides a base station, and a functional block diagram of the base station may be shown in FIG. 9 . The base station may include one or more processors 100 (only one is shown in FIG. 9 ), a memory 101, and a computer program 102 stored in the memory 101 and operable on the one or more processors 100, for example, based on multi-user Procedure for downlink hybrid broadcast-unicast transmission of overlay transmission technology. When one or more processors 100 execute the computer program 102, various steps in the method embodiment of the downlink hybrid broadcast-unicast transmission based on the multi-user overlay transmission technology can be realized. Alternatively, when one or more processors 100 execute the computer program 102, they can realize the functions of the modules/units in the embodiment of the device for downlink hybrid broadcast-unicast transmission based on multi-user overlay transmission technology, which is not limited here.

In one embodiment, the so-called processor 100 may be a central processing unit (Central Processing Unit, CPU), and may also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.

In one embodiment, the storage 101 may be an internal storage unit of the electronic device, such as a hard disk or memory of the electronic device. The memory 101 can also be an external storage device of the electronic device, such as a plug-in hard disk equipped on the electronic device, a smart memory card (smart media card, SMC), a secure digital (secure digital, SD) card, a flash memory card (flash card) wait. Further, the memory 101 may also include both an internal storage unit of the electronic device and an external storage device. The memory 101 is used to store computer programs and other programs and data required by the base station. The memory 101 can also be used to temporarily store data that has been output or will be output.

Those skilled in the art can understand that the functional block diagram shown in Figure 9 is only a block diagram of a partial structure related to the solution of the present invention, and does not constitute a limitation on the base station to which the solution of the present invention is applied. The specific base station includes There may be more or fewer components than shown in the figures, or certain components may be combined, or have different component arrangements.

Those of ordinary skill in the art can understand that realizing all or part of the processes in the methods of the above embodiments can be completed by instructing related hardware through computer programs, and the computer programs can be stored in a non-volatile computer-readable storage medium , when the computer program is executed, it may include the procedures of the embodiments of the above-mentioned methods. Wherein, any references to memory, storage, operational database or other media used in the various embodiments provided by the present invention may include non-volatile and/or volatile memory. Nonvolatile memory can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Dual Operating Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

To sum up, the present invention discloses a downlink hybrid broadcast-unicast transmission method based on multi-user overlay transmission technology. The method includes: the base station obtains channel state information of broadcast services from cell edge users, and determines broadcast service information according to the channel state information. Coding and modulation scheme; the base station selects a hotspot service area in the cell, and selects a unicast service with suitable channel conditions from the hotspot service area to superimpose transmission with the broadcast service; the base station combines the unicast service with the broadcast service Non-orthogonal multiplexing to obtain a composite service, and according to the channel quality information fed back by the unicast service user, determine the coding and modulation scheme of the composite service, and replace the broadcasting service coding and modulation scheme with the coding and modulation scheme of the composite service . The present invention can provide additional unicast services for the system without affecting the coverage performance of broadcast services, and improve the overall transmission efficiency of unicast services.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (13)

1. A downlink hybrid broadcast unicast transmission method based on multi-user overlay transmission technology, characterized in that the method comprises: The base station obtains channel state information of the broadcast service from the cell edge user, and determines a coding and modulation scheme of the broadcast service according to the channel state information; The base station selects a hotspot service area in the cell, and selects a unicast service with suitable channel conditions from the hotspot service area and superimposes transmission with the broadcast service; The base station non-orthogonally multiplexes the unicast service and the broadcast service to obtain a composite service, and determines the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user, and uses the composite service The coding and modulation scheme of the broadcasting service replaces the coding and modulation scheme of the broadcasting service. 2. The downlink hybrid broadcast-unicast transmission method based on multi-user overlay transmission technology according to claim 1, wherein the base station obtains channel state information of broadcast services from cell edge users, and according to the channel state information Determine the coding and modulation scheme for broadcasting services, including: The base station sends a channel state reference signal to the cell edge user; The cell edge user performs channel estimation according to the channel state reference signal, and feeds back the signal state information of the broadcast service to the base station, where the channel state information includes a received signal-to-noise ratio; The base station selects an appropriate broadcast service coding and modulation scheme according to the signal state information, and the broadcast service coding and modulation scheme includes an equivalent constellation mapping order and a channel coding code rate. 3. The downlink hybrid broadcast and unicast transmission method based on multi-user overlay transmission technology according to claim 1, wherein the base station selects a hotspot service area in the cell, and selects a channel from the hotspot service area The superimposed transmission of unicast services with suitable conditions and the broadcast services includes: The base station selects a hotspot service area in the cell; The base station sorts the channel state information of the unicast service users in the selected hotspot service area according to the channel state information fed back by the unicast service users in the cell, and selects the unicast service with suitable channel conditions for superimposed transmission with the broadcast service. 4. The downlink hybrid broadcast unicast transmission method based on multi-user superimposed transmission technology according to claim 3, wherein the coding and modulation scheme of the composite service is determined according to the channel quality value fed back by the unicast service user ,include: The unicast service user periodically measures the channel quality information, and maps the channel quality information into a CQI value and reports it to the base station; The base station selects a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, and uses the target coding and modulation scheme as the coding and modulation scheme of the composite service, and the composite The coding and modulation scheme of the service includes: the order of composite constellation mapping and the code rate of channel coding. 5. The downlink hybrid broadcast and unicast transmission method based on multi-user superposition transmission technology according to claim 4, wherein the base station selects the CQI value in a preset coding and modulation scheme according to the CQI value The corresponding target coded modulation schemes include: The base station determines a received signal-to-noise ratio range corresponding to the CQI value according to the CQI value; According to the received signal-to-noise ratio range, it is determined to select a target coding and modulation scheme corresponding to the received signal-to-noise ratio range among the preset coding and modulation schemes. 6. The downlink hybrid broadcast and unicast transmission method based on multi-user overlay transmission technology according to claim 1, wherein the method further comprises: The base station notifies the unicast service user of the coding and modulation scheme channel control information of the composite service. 7. A downlink hybrid broadcast-unicast transmission system based on multi-user overlay transmission technology, characterized in that the system includes: a base station and a cell, and the base station includes: The broadcast service analysis module is used to obtain the channel state information of the broadcast service from the cell edge users, and determine the coding and modulation scheme of the broadcast service according to the channel state information; A unicast service determination module, configured to select a hotspot service area in the cell, and select a unicast service with suitable channel conditions from the hotspot service area for superimposed transmission with the broadcast service; A coding and modulation scheme determination module, configured to non-orthogonally multiplex the unicast service and the broadcast service to obtain a composite service, and determine the coding and modulation scheme of the composite service according to the channel quality information fed back by the unicast service user , and replace the coding and modulation scheme of the broadcast service with the coding and modulation scheme of the composite service. 8. The downlink hybrid broadcast-unicast transmission system based on multi-user overlay transmission technology according to claim 7, wherein the broadcast service analysis module comprises: a signal sending unit, configured for the base station to send a channel state reference signal to a cell edge user; The state receiving unit is used for the cell edge user to perform channel estimation according to the channel state reference signal, and to feed back the signal state information of the broadcast service to the base station, and the channel state information includes a received signal-to-noise ratio; The scheme determination unit is used for the base station to select an appropriate broadcast service coding and modulation scheme according to the signal state information, and the broadcast service coding and modulation scheme includes an equivalent constellation mapping order and a channel coding code rate. 9. The downlink hybrid broadcast-unicast transmission system based on multi-user overlay transmission technology according to claim 7, wherein the unicast service determination module comprises: The base station selects a hotspot service area in the cell; The base station sorts the channel state information of the unicast service users in the selected hotspot service area according to the channel state information fed back by the unicast service users in the cell, and selects the unicast service with suitable channel conditions to be superimposed with the broadcast service for transmission. 10. The downlink hybrid broadcast-unicast transmission system based on multi-user superimposed transmission technology according to claim 9, wherein the encoding and modulation scheme determination module comprises: The CQI value determination unit is used for unicast service users to periodically measure channel quality information, and map the channel quality information into a CQI value and report to the base station; A scheme selection unit, configured for the base station to select a target coding and modulation scheme corresponding to the CQI value from preset coding and modulation schemes according to the CQI value, and use the target coding and modulation scheme as the coding of the composite service Modulation scheme, the coding and modulation scheme of the composite service includes: the order of composite constellation mapping and the channel coding code rate. 11. The downlink hybrid broadcast-unicast transmission system based on multi-user superimposition transmission technology according to claim 10, characterized in that the scheme selection unit comprises: A signal-to-noise ratio range determination subunit, configured for the base station to determine a received signal-to-noise ratio range corresponding to the CQI value according to the CQI value; The target scheme determining subunit is configured to determine a target coding and modulation scheme corresponding to the range of the receiving signal-to-noise ratio among the preset coding and modulation schemes according to the range of the receiving signal-to-noise ratio. 12. The downlink hybrid broadcast-unicast transmission system based on multi-user superimposed transmission technology according to claim 7, wherein the base station further comprises: The information notifying module is used for notifying the unicast service user of the coding and modulation scheme channel control information of the composite service. 13. A base station, characterized in that the base station includes a memory, a processor, and a downlink hybrid broadcast-unicast transmission program based on multi-user superimposed transmission technology that is stored in the memory and can run on the processor, and the processor executes a program based on When performing the downlink hybrid broadcast and unicast transmission procedure of the multi-user overlay transmission technology, the steps of the downlink hybrid broadcast and unicast transmission method based on the multi-user overlay transmission technology according to any one of claims 1-6 are implemented.

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