Multi-carrier distributed network synchronization method and system based on time-sharing sub-band multiplexing

Abstract

The invention discloses a multicarrier distributed network synchronization method and system based on time-sharing sub-band multiplexing, and belongs to the field of wireless communication, the method comprises a self-organizing communication network, the self-organizing communication network comprises a logic center node and common nodes, and the logic center node is connected with the common nodes; based on the self-organizing network, a time-sharing sub-band multiplexing mode is adopted, a synchronous channel and a service channel are decoupled, a broadcast time slot deploys the synchronous channels of all nodes on fixed frequency domain sub-carrier resources, and only the service channel is transmitted in the service time slot without carrying the synchronous channel. According to the invention, the implementation overhead and the implementation complexity of the receiver are reduced, and the spectrum efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication, and more specifically, to a multi-carrier distributed network synchronization method and system based on time-division sub-band multiplexing. Background Art

[0002] In a centralized networking communication system based on OFDM, such as an LTE / 5G terrestrial mobile communication system, for a single-point-to-multipoint link (e.g., the LTE / 5G downlink), a time-domain inserted synchronization channel is used to achieve synchronization. The central node inserts a time-domain synchronization sequence at the head of the time slot and transmits it for all terminals to synchronize; for a multi-point-to-single-point link (e.g., the LTE / 5G uplink), a frequency-domain inserted pilot is used. Different terminals insert pilots (e.g., DMRS, SRS) in different frequency-domain resources and transform them into the time domain for transmission, so that the central node can synchronize all terminals: The central node measures the time deviation of the time slot signals transmitted by the corresponding terminals using the pilot signals in different frequency-domain resources and feeds back the time deviation information to the terminals for transmission time offset adjustment. In a self-organizing network communication system based on single-carrier TDMA, the links between nodes use the method of inserting synchronization sequences in the time domain to achieve synchronization. Each distributed node inserts a time-domain synchronization sequence at the head of the time slot and transmits it for other nodes to capture and synchronize.

[0003] In the prior art, in a self-organizing network communication system based on OFDM, due to the adoption of the OFDMA multiple access method, different nodes are allocated different time slots and frequency-domain resources. There are two synchronization schemes between nodes: (1) The method of inserting synchronization sequences in the time domain: In a self-organizing network communication system based on OFDM, each node is allocated different time slots and frequency-domain resources. Each node inserts a time-domain synchronization sequence at the head of its occupied time slot and transmits it for other nodes to capture and synchronize. The bandwidth of the time-domain synchronization sequence of this node is the same as the bandwidth of its allocated frequency-domain resources. When capturing the time-domain synchronization sequence between nodes, it is necessary to first filter and extract the signals within the bandwidth occupied by the measured node through a band-pass filter, and then perform sliding window correlation to capture the time-domain synchronization sequence, so as to find the starting boundary of the time slot signal and perform time offset compensation and demodulation. (2) The method of inserting pilots in the frequency domain: In a self-organizing network communication system based on OFDM, different nodes insert pilots in different frequency-domain resources and transform them into the time domain for transmission for other nodes to synchronize: Each node measures the time deviation of the time slot signals sent by the corresponding node using the pilot signals in the frequency-domain resources occupied by the measured node, so as to find the starting boundary of the time slot signal and perform time offset compensation and demodulation.

[0004] In the current OFDM-based self-organizing network communication system, the main disadvantages of the node synchronization scheme are as follows: (1) Problems with the method of inserting synchronization sequences in the time domain: Since the frequency-domain subcarrier resources allocated to each node are different, the frequency-domain subcarrier resources occupied by the synchronization channels of different nodes are also different. Therefore, each node needs to design additional band-pass filters with different frequencies and bandwidths for other nodes to filter out the synchronization channels of other nodes respectively for synchronization search. This scheme has a high implementation complexity, a large amount of calculation, and it is difficult to dynamically adjust the filter parameters at the time-slot level. Therefore, it cannot adapt to the flexible frequency-domain resource allocation method that changes dynamically at the time-slot level. (2) Problems with the method of inserting pilot signals in the frequency domain: Since the synchronization error between nodes in the self-organizing network is large, the time offset may exceed the cyclic prefix CP of OFDM, so the time deviation between nodes cannot be effectively measured through the frequency-domain pilot signal. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a multi-carrier distributed network synchronization method and system based on time-sharing sub-band multiplexing, which reduces the implementation cost and the implementation complexity of the receiver, and improves the spectral efficiency.

[0006] The purpose of the present invention is achieved through the following solutions:

[0007] A multi-carrier distributed network synchronization method based on time-sharing sub-band multiplexing, including a self-organizing communication network, the self-organizing communication network includes a logical central node and ordinary nodes, and the logical central node is connected to the ordinary nodes;

[0008] Based on the self-organizing network, in a time-sharing sub-band multiplexing manner, the synchronization channel is decoupled from the service channel. In the broadcast time slot, the synchronization channels of all nodes are deployed on fixed frequency-domain subcarrier resources, and only the service channel is transmitted in the service time slot without carrying the synchronization channel.

[0009] Further, the method of using time-sharing sub-band multiplexing to decouple the synchronization channel from the service channel, deploying the synchronization channels of all nodes on fixed frequency-domain subcarrier resources in the broadcast time slot, and only transmitting the service channel in the service time slot without carrying the synchronization channel specifically includes the following sub-steps:

[0010] Step S1, broadcast time slot stage: Each node broadcasts and sends the synchronization channel across the network in turn, and other nodes receive the synchronization channel and measure and record the time offset information of the transmitting node into the local time offset table;

[0011] Step S2, business time slot stage: The logical central node divides the OFDM time-frequency resources into multiple service channels with different bandwidths according to the service requirements of the ad hoc network, and allocates each service channel to the corresponding node to send data; after the transmitting node sends out the service channel, the receiving node receives the service channel, and completes the reception timing compensation according to the timing offset information of the corresponding transmitting node maintained in the local timing offset table, and then performs demodulation and decoding.

[0012] Further, in the way of time-division sub-band multiplexing, the synchronization channel and the service channel are decoupled. The synchronization channels of all nodes are deployed on the fixed frequency-domain subcarrier resources in the broadcast time slot, and only the service channels are transmitted in the business time slot without carrying the synchronization channel, which specifically includes the following sub-steps:

[0013] Step 1, in the OFDM frequency-domain resources, the system bandwidth contains (K + L) subcarriers. K subcarriers are separated as independent synchronization resources, and are allocated to different nodes by using the multiple access method based on TDMA, and the synchronization channel is sent;

[0014] Step 2, assume that within a scheduling frame period, there are M time slots. Among them, the first N time slots are broadcast time slots, and the subsequent (M - N) time slots are business time slots;

[0015] The broadcast time slot contains a synchronization channel and a broadcast channel. Among them, the synchronization channel occupies K subcarriers and is used for the receiving node to measure the signal timing offset. The broadcast channel occupies L subcarriers and is used to carry the public information broadcast to all other nodes. Each node sequentially occupies a broadcast time slot to send the synchronization channel and the broadcast channel to all other nodes;

[0016] The business time slot consists of multiple service channels. The service channel is a pure data channel without a synchronization channel; the logical central node divides the OFDM time-frequency resources into different service channels as needed according to the service requirements of the ad hoc network and allocates them to the corresponding nodes for transmission; after the receiving node receives the service channel, it performs reception timing compensation according to the timing offset value of the corresponding transmitting node recorded locally and then performs demodulation and decoding.

[0017] Further, in Step 2, the public information includes: a resource allocation table, a routing table, and node status information.

[0018] Further, in the way of time-division sub-band multiplexing, the synchronization channel and the service channel are decoupled. The synchronization channels of all nodes are deployed on the fixed frequency-domain subcarrier resources in the broadcast time slot, and only the service channels are transmitted in the business time slot without carrying the synchronization channel, which specifically includes the following sub-steps:

[0019] Step (1), at broadcast time slot n = 1, the logical central node 1 sends a synchronization channel and a broadcast channel. The ordinary nodes 2 to N measure the reception time offset according to the synchronization channel sent by the logical central node 1, and achieve reception time slot synchronization alignment by adjusting the local reception timing. After completing the reception time slot synchronization alignment, the ordinary nodes 2 to N record the time offset t of receiving the time slot sent by the logical central node 1 21 ~t N1 in the local time offset table. Among them, the ordinary nodes 2 to N have achieved reception time slot synchronization alignment by adjusting the local reception timing, and record t 21 = 0, t 31 = 0,..., t N1 = 0;

[0020] Step (2), let n = n + 1. At broadcast time slot n, the ordinary node n sends a synchronization channel and a broadcast channel based on the local reception timing boundary. Other nodes measure the reception time deviation {t jn |j = 1,..., N, and j ≠ n} of the time slot signal sent by the ordinary node n according to the synchronization channel sent by the ordinary node n, and record it in the local time offset table of their respective nodes;

[0021] Step (3), judge the loop traversal condition. If n < N, enter Step (2), otherwise enter Step (4);

[0022] Step (4), after Steps (1) to (3), all nodes have completed the network-wide synchronization based on the logical central node 1. The content of the local time offset table recorded by each node includes: the node n records the time offset set {t nj |j = 1,..., N, and j ≠ n} of receiving other transmitting nodes j, where n = 1,..., N;

[0023] Step (5), in the service time slot, the logical central node divides the OFDM time-frequency resources into different service channels according to the service requirements of the ad hoc network and allocates them to the corresponding nodes for transmission. For the service channels, each node no longer sends a synchronization header;

[0024] Step (6), the receiving node completes the reception timing compensation according to the time offset information of receiving other corresponding transmitting nodes maintained in the local time offset table and then performs demodulation and decoding;

[0025] Step (7), judge whether the service time slot of the current scheduling frame period has ended. If not, enter Step (5), otherwise, enter the next scheduling frame period;

[0026] In the next scheduling frame period, each node polls cyclically to send a synchronization channel and a broadcast channel in the broadcast time slot. Each node receives and measures the time offset information of other nodes, and updates the time offset information to the local time offset table of each node. In the service time slot, the receiving node completes the reception timing compensation according to the time offset information of other corresponding transmitting nodes maintained in the local time offset table, and then performs demodulation and decoding.

[0027] Further, in step (6), the receiving node completes the reception timing compensation according to the time offset information of other corresponding transmitting nodes maintained in the local time offset table, and then performs demodulation and decoding, which specifically includes the following sub-steps:

[0028] Node j sends a service channel in the service time slot. After node i receives the service channel sent by node j, it first compensates the reception time offset according to the time offset information t in the local time offset table, and then performs demodulation and decoding, where i = 1,..., N, j = 1,..., N, and i ≠ j. ij

[0029] A multi-carrier distributed network synchronization system based on time-division sub-band multiplexing includes a computer device, characterized in that a computer program is stored in the memory of the computer device, and when the computer program is loaded by the processor of the computer device, the method described in any one of the above is executed.

[0030] The beneficial effects of the present invention include:

[0031] (1) In the present invention, the synchronization channel and the service channel are decoupled, and the synchronization channels of all nodes are deployed on fixed frequency-domain subcarrier resources. Therefore, all nodes only need to design a filter with a fixed center frequency and a fixed bandwidth to realize the filtering of the synchronization channel, which simplifies the design complexity of the filter and reduces the implementation cost.

[0032] (2) The service channel of the present invention does not need to carry a synchronization header, which reduces the synchronization header overhead and improves the spectral efficiency.

[0033] (3) The receiving node of the present invention does not need to measure the time offset of the service channel to perform time offset compensation, which reduces the implementation complexity of the receiver.

[0034] (4) The present invention solves the problems of synchronization channel filtering and searching in the multi-user multiplexing scenario, and greatly reduces the difficulty of slot synchronization implementation in the scenario where the service channel dynamically changes the frequency-domain resources at the slot level. Description of the Drawings

[0035] ​To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0036] Figure 1 Schematic diagram of the system composition of the present invention;

[0037] Figure 2 Schematic diagram of the time-frequency resource allocation of the present invention;

[0038] Figure 3 System working process of the present invention;

[0039] Figure 4 Schematic diagram of the time-frequency resource allocation in the first embodiment of the present invention. Detailed implementation manners

[0040] All the features disclosed in all the embodiments in this specification, or all the steps in the methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or extended, replaced in any way.

[0041] The abbreviations in this application are explained as follows:

[0042] LTE: Long Term Evolution, one of the 4th generation mobile communication standards (4G);

[0043] DMRS: Demodulation Reference Signal;

[0044] SRS: Sounding Reference Signal;

[0045] TDMA: Time Division Multiple Access;

[0046] OFDM: Orthogonal Frequency Division Multiplexing;

[0047] OFDMA: Orthogonal Frequency Division Multiple Access.

[0048] The present invention aims to solve the technical problems in an OFDM-based ad hoc network communication system, including the complex design and high implementation cost of the synchronization channel bandpass filter caused by the time-domain inserted synchronization sequence scheme, and the problem of being unable to adapt to flexible frequency-domain resource allocation with slot-level dynamic changes.

[0049] In the overall technical concept of the present invention, the system of the embodiment of the present invention consists of N nodes to form an ad hoc network, where there is 1 logical central node and N - 1 ordinary nodes. Within a scheduling frame period, it contains M time slots, where the first N time slots are broadcast time slots, and the subsequent (M - N) time slots are service time slots. By adopting the time-division sub-band multiplexing method, the synchronization channel and the service channel are decoupled. The synchronization channels of all nodes are deployed on fixed frequency-domain subcarrier resources during the broadcast time slots, and only the service channels are transmitted during the service time slots, without the need to carry the synchronization channel anymore.

[0050] During the broadcast time slots, each node j broadcasts and sends the synchronization channel to the entire network in sequence, and other nodes n receive the synchronization channel and measure and record the time offset information t of the transmitting node j nj to the local time offset table.

[0051] During the service time slots, the logical central node divides the OFDM time-frequency resources into multiple service channels with different bandwidths according to the service requirements of the ad hoc network, and allocates each service channel to the corresponding node to send data; after the transmitting node j sends out the service channel, the receiving node n receives the service channel, and according to the time offset information t of the corresponding transmitting node maintained in the local time offset table nj completes the receiving timing compensation and then performs demodulation and decoding.

[0052] Furthermore, the system composition and working process of the embodiment of the present invention are described in detail as follows: As Figure 1 shown, the system of the embodiment of the present invention consists of N nodes to form an ad hoc network, where there is 1 logical central node and N - 1 ordinary nodes, and communication links are established between each node. Each node polls and broadcasts the synchronization channel periodically, and this synchronization channel contains a synchronization sequence for measuring the time offset. When the receiving node receives the synchronization channel of the logical central node, it measures the time offset information of the signal sent by the logical central node and adjusts its own receiving timing boundary to align with the signal boundary sent by the logical central node; when the receiving node receives the synchronization channel of an ordinary node, it measures and records the time offset information of the current ordinary node into the local time offset table.

[0053] As Figure 2 shown, in the OFDM frequency-domain resources, the system bandwidth of the embodiment of the present invention contains (K + L) subcarriers, and K subcarriers are separated as independent synchronization resources, which are allocated to different nodes by using a TDMA-based multiple access method and the synchronization channel is sent.

[0054] Within a scheduling frame period, there are M time slots. Among them, the first N time slots are broadcast time slots, and the subsequent (M - N) time slots are service time slots.

[0055] The broadcast time slots include a synchronization channel and a broadcast channel. Among them, the synchronization channel occupies K subcarriers and is used for the receiving node to measure the signal time offset. The broadcast channel occupies L subcarriers and is used to carry public information broadcast to all other nodes, such as resource allocation tables, routing tables, node status, etc. Each node sequentially occupies one broadcast time slot to send the synchronization channel and the broadcast channel to all other nodes.

[0056] The service time slots are composed of multiple service channels. The service channels are pure data channels without a synchronization channel. The logical central node divides the OFDM time-frequency resources into different service channels according to the service requirements of the ad hoc network and allocates them to the corresponding nodes for transmission. After receiving the service channel, the receiving node performs reception timing compensation based on the time offset value of the corresponding transmitting node recorded locally and then demodulates and decodes.

[0057] The advantage of the embodiment of the present invention is that the synchronization channel and the service channel are decoupled, and the synchronization channels of all nodes are deployed on fixed frequency-domain subcarrier resources. Therefore, all nodes only need to design a filter with a fixed center frequency and fixed bandwidth to implement the filtering of the synchronization channel, which simplifies the design complexity of the filter and reduces the implementation cost. On the other hand, the service channel does not need to carry a synchronization header, reducing the synchronization header overhead and improving the spectrum efficiency; and the receiving node does not need to measure the time offset of the service channel to perform time offset compensation, reducing the implementation complexity of the receiver; at the same time, it solves the problems of synchronization channel filtering and searching in the multi-user multiplexing scenario, and greatly reduces the difficulty of slot synchronization implementation in the scenario where the service channel dynamically changes the frequency-domain resources at the slot level.

[0058] Furthermore, as Figure 3 shown, the system working process of the embodiment of the present invention is divided into two stages:

[0059] (1) Broadcast time slot stage: Each node j broadcasts and sends the synchronization channel across the network in sequence, and other nodes n receive the synchronization channel and measure and record the time offset information t nj of the transmitting node j into the local time offset table, where t nj represents the time deviation of the receiving node n receiving the slot signal of the transmitting node j, j = 1,..., N, n = 1,..., N.

[0060] (2) Service time slot stage: In the service time slot, the logical central node divides the OFDM time-frequency resources into multiple service channels with different bandwidths according to the service requirements of the ad hoc network, and allocates each service channel to the corresponding node (the nodes here include ordinary and logical nodes) to send data; after the transmitting node j sends out the service channel, the receiving node n receives the service channel and performs demodulation and decoding after completing the reception timing compensation according to the timing offset information t of the corresponding transmitting node maintained in the local timing offset table. nj After completing the reception timing compensation, demodulation and decoding are carried out.

[0061] The specific description of the system working process of the embodiment of the present invention is as follows: The process of synchronizing the whole network with the logical central node as the reference and periodically maintaining and updating the synchronization information:

[0062] (1) In the broadcast time slot n = 1, the logical central node 1 sends a synchronization channel and a broadcast channel. The ordinary nodes 2 to N measure the reception timing offset according to the synchronization channel sent by the logical central node 1, and achieve the synchronization alignment of the reception time slot by adjusting the local reception timing. After completing the synchronization alignment of the reception time slot, the ordinary nodes 2 to N record the timing offset t 21 ~t N1 recorded in the local timing offset table. Among them, since the ordinary nodes 2 to N have achieved the synchronization alignment of the reception time slot by adjusting the local reception timing, so record t 21 = 0, t 31 = 0,..., t N1 = 0.

[0063] (2) Let n = n + 1. In the broadcast time slot n, the ordinary node n sends a synchronization channel and a broadcast channel based on the local reception timing boundary. Other nodes (the nodes here include ordinary and logical nodes) measure the reception time deviation {t jn |j = 1,..., N, and j ≠ n} of the signal in the transmission time slot of the ordinary node n according to the synchronization channel sent by the ordinary node n, and record it in the local timing offset table of their respective nodes.

[0064] (3) Judge the loop traversal condition. If n < N, then enter step (2), otherwise enter step (4).

[0065] (4) After steps (1) to (3), all nodes have completed the synchronization of the whole network with the logical central node 1 as the reference. The content of the local timing offset table recorded by each node (the nodes here include ordinary and logical nodes) includes: the node n records the set of timing offsets {t nj |j = 1,..., N, and j ≠ n} of receiving other transmitting nodes j, where n = 1,..., N.

[0066] (5) During the service time slot, the logical central node divides the OFDM time-frequency resources into different service channels as needed according to the service requirements of the ad hoc network and allocates them to the corresponding nodes for transmission. For the service channels, each node no longer needs to transmit a synchronization header.

[0067] (6) The receiving node completes the reception timing compensation according to the timing offset information of other corresponding transmitting nodes maintained in the local timing offset table and then performs demodulation and decoding. For example, when node j transmits a service channel during the service time slot, after node i receives the service channel transmitted by node j, it first compensates for the reception timing offset according to the timing offset information t in the local timing offset table, and then performs demodulation and decoding, where i = 1, …, N, j = 1, …, N, and i ≠ j. ij Compensate the reception timing offset and then perform demodulation and decoding, where i = 1, …, N, j = 1, …, N, and i ≠ j.

[0068] (7) Determine whether the service time slot of the current scheduling frame period has ended. If not, go to step (5); otherwise, enter the next scheduling frame period.

[0069] In the next scheduling frame period, each node polls cyclically to transmit the synchronization channel and the broadcast channel during the broadcast time slot. Each node receives and measures the timing offset information of other nodes and updates the timing offset information to the local timing offset table of each node. During the service time slot, the receiving node completes the reception timing compensation according to the timing offset information of other corresponding transmitting nodes maintained in the local timing offset table and then performs demodulation and decoding.

[0070] In other preferred embodiments of the present invention, the following Embodiment 1 is provided:

[0071] This Embodiment 1 is applied to the application scenario of node synchronization in an OFDM-based ad hoc network communication system, involving network elements: 1 logical central node and N - 1 ordinary nodes. Taking 3 nodes as an example to introduce the solution of this embodiment, where node 1 is the logical central node, and nodes 2 and 3 are ordinary nodes.

[0072] As Figure 4 shown, in the OFDM frequency domain resources, the system bandwidth includes 800 subcarriers, and K = 160 subcarriers are separated as independent synchronization resources, which are allocated to different nodes by using a TDMA-based multiple access method and the synchronization channel is transmitted.

[0073] In one scheduling frame period, it includes M = 10 time slots, where the first N = 3 time slots are broadcast time slots, and the subsequent (M - N) = 7 time slots are service time slots.

[0074] The broadcast time slot contains a synchronization channel and a broadcast channel. Among them, the synchronization channel occupies K = 160 subcarriers and is used for the receiving node to measure the signal time offset. The broadcast channel occupies L = 640 subcarriers and is used to carry the public information broadcast to all other nodes, such as the resource allocation table, routing table, node status and other information. Each node sequentially occupies a broadcast time slot to send the synchronization channel and the broadcast channel to all other nodes.

[0075] The service time slot consists of multiple service channels. The service channel is a pure data channel without a synchronization channel. The logical central node divides the OFDM time-frequency resources into three types of service channels with different bandwidths according to the service requirements of the ad hoc network. The bandwidths are 400 subcarriers, 300 subcarriers, and 100 subcarriers respectively, and the service channels with each bandwidth are assigned to Node 1, Node 2, and Node 3 for transmission. After receiving the service channel, the receiving node performs receive timing compensation according to the time offset value of the corresponding transmitting node recorded locally and then demodulates and decodes.

[0076] The specific description of the system working process of this embodiment is as follows: The process of synchronizing the entire network with the logical central node as the reference and periodically maintaining and updating the synchronization information:

[0077] (1) In broadcast time slot 1, the logical central node 1 sends the synchronization channel and the broadcast channel. The ordinary nodes 2 and 3 measure the receive time offset according to the synchronization channel sent by the logical central node 1, and achieve receive time slot synchronization alignment by adjusting the local receive timing. After completing the receive time slot synchronization alignment, node 2 receives the time deviation t 21 = 0 of node 1 and records t 21 into the local time offset table. Node 3 receives the time deviation t 31 = 0 of node 1 and records t 31 into the local time offset table.

[0078] (2) In broadcast time slot 2, the ordinary node 2 sends the synchronization channel and the broadcast channel based on the local receive timing boundary. The logical central node 1 measures the receive time deviation t 12 of the time slot signal sent by the ordinary node 2 according to the synchronization channel sent by the ordinary node 2, and records t 12 into the local time offset table. The ordinary node 3 measures the receive time deviation t 32 of the time slot signal sent by the ordinary node 2 according to the synchronization channel sent by the ordinary node 2 and records t 32 into the local time offset table.

[0079] (3) In broadcast time slot 3, the ordinary node 3 sends the synchronization channel and the broadcast channel based on the local receive timing boundary. The logical central node 1 measures the receive time deviation t 13 of the time slot signal sent by the ordinary node 3 according to the synchronization channel sent by the ordinary node 3, and t13 Recorded in the local time deviation table, ordinary node 2 measures the receiving time deviation t of the time slot signal sent by ordinary node 3 based on the synchronization channel sent by ordinary node 3 23 And t 23 Recorded in the local time deviation table.

[0080] (4) After steps (1) to (3), all nodes have completed the whole network synchronization based on the logical center node 1. Each node records the time offset information received from other nodes in the local time offset table. The content of the local time offset table of each node includes: Node 1 records the time offset information received from other nodes t 12 ,t 13 Node 2 records the time offset t of receiving other nodes 21 ,t 23 Node 3 records the time offset t of receiving other nodes 31 ,t 32 .

[0081] (5) In the service time slot, the logical central node divides the OFDM time-frequency resources into three types of service channels with different bandwidths according to the service requirements of the ad hoc network. The bandwidths are 400 subcarriers, 300 subcarriers, and 100 subcarriers, respectively. The service channels of each bandwidth are allocated to node 1, node 2, and node 3 for transmission. For the service channels, each node no longer needs to send a synchronization header.

[0082] (6) The receiving node completes the receiving timing compensation according to the time offset information of other corresponding transmitting nodes maintained in the local time offset table before demodulation and decoding. For example, node j sends a service channel in the service time slot. After receiving the service channel sent by node j, node i first compensates the received signal according to the time offset information t in the local time offset table. ij Compensate for the receiving time deviation, then perform demodulation and decoding, where i=1,…,3, j=1,…,3, and i≠j.

[0083] (7) Determine whether the service time slot of the current scheduling frame period has been sent. If not, proceed to step (5); otherwise, proceed to the next scheduling frame period.

[0084] In the next scheduling frame cycle, each node periodically polls to send the synchronization channel and broadcast channel in the broadcast time slot. Each node receives and measures the time deviation information of other nodes, and updates the time deviation information to the local time deviation table of each node. In the service time slot, the receiving node completes the receiving timing compensation according to the time deviation information of other corresponding transmitting nodes maintained in the local time deviation table, and then performs demodulation and decoding.

[0085] In the first embodiment, the synchronization channel is decoupled from the service channel, and a synchronization channel with a fixed center frequency and a fixed bandwidth is designed in the broadcast time slots allocated to each node. Therefore, the design complexity of the synchronization channel filter is simplified, and the implementation cost is reduced. On the other hand, the service channel no longer carries a synchronization header, improving the spectral efficiency; and the receiving node does not need to measure the time offset of the service channel, reducing the implementation complexity of the receiver; at the same time, the difficulty of implementing time slot synchronization in the scenario where the service channel dynamically changes frequency domain resources at the time slot level is greatly reduced.

[0086] The technical solution of the first embodiment of the present invention has the following advantages:

[0087] 1) In the technical solution of the first embodiment, a synchronization channel with a fixed center frequency and a fixed bandwidth is designed in the broadcast time slots allocated to each node. Therefore, all nodes search for the synchronization channel in the signal with this frequency point and bandwidth and complete the time offset measurement, simplifying the design complexity of the synchronization channel filter and reducing the implementation cost.

[0088] 2) In the technical solution of the first embodiment, for the service channel, it no longer carries a synchronization header. Therefore, the synchronization header overhead is reduced, and the spectral efficiency is improved.

[0089] 3) In the technical solution of the first embodiment, the receiving node compensates the time offset of the received signal through the local time offset table. Therefore, it does not need to measure the time offset of the service channel, reducing the implementation complexity of the receiver.

[0090] 4) In the technical solution of the first embodiment, since the synchronization channel is decoupled from the service channel, the problems of synchronization channel filtering and searching in the multi-user multiplexing scenario are solved, and the difficulty of implementing time slot synchronization in the scenario where the service channel dynamically changes frequency domain resources at the time slot level is greatly reduced.

[0091] The units described in the embodiments of the present invention can be implemented in software or in hardware, and the described units can also be provided in a processor. Among them, the names of these units do not constitute a limitation to the unit itself in some cases.

[0092] According to one aspect of the embodiments of the present invention, there is provided a computer program product or a computer program, the computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the methods provided in the above various optional implementation manners.

[0093] As another aspect, an embodiment of the present invention further provides a computer-readable medium, which may be included in the electronic device described in the above embodiment; or may exist alone without being assembled into the electronic device. The above computer-readable medium carries one or more programs, and when the one or more programs are executed by an electronic device, the electronic device implements the method described in the above embodiment.

Claims

1. A multi-carrier distributed network synchronization method based on time-division sub-band multiplexing, characterized in that: The self-organizing communication network includes a logical central node and common nodes, and the logical central node is connected to the common nodes; Based on the self-organizing network, the synchronization channel is decoupled from the service channel by using time-division sub-band multiplexing. The synchronization channels of all nodes are deployed on fixed frequency domain sub-carrier resources in the broadcast time slot, and only the service channel is transmitted in the service time slot without carrying the synchronization channel.

2. The multi-carrier distributed network synchronization method based on time-division sub-band multiplexing according to claim 1, characterized in that: The method of using time-division sub-band multiplexing to decouple the synchronization channel from the service channel, deploying the synchronization channels of all nodes on fixed frequency domain sub-carrier resources in the broadcast time slot, and transmitting only the service channel in the service time slot without carrying the synchronization channel, specifically includes the following sub-steps: Step S1, broadcast time slot phase: each node broadcasts the synchronization channel to the entire network in turn, and other nodes receive the synchronization channel and measure and record the time deviation information of the transmitting node into the local time deviation table; Step S2, service time slot stage: the logical central node divides the OFDM time-frequency resources into multiple service channels with different bandwidths according to the service needs of the self-organizing network, and allocates each service channel to the corresponding node to send data; after the transmitting node sends the service channel, the receiving node receives the service channel and completes the receiving timing compensation according to the time deviation information of the corresponding transmitting node maintained in the local time deviation table before demodulation and decoding.

3. The multi-carrier distributed network synchronization method based on time-division sub-band multiplexing according to claim 1, characterized in that: The method of using time-division sub-band multiplexing to decouple the synchronization channel from the service channel, deploying the synchronization channels of all nodes on fixed frequency domain sub-carrier resources in the broadcast time slot, and transmitting only the service channel in the service time slot without carrying the synchronization channel, specifically includes the following sub-steps: Step 1: In the OFDM frequency domain resources, the system bandwidth includes (K+L) subcarriers, K subcarriers are separated as independent synchronization resources, allocated to different nodes using a TDMA-based multiple access method, and a synchronization channel is sent; Step 2, assuming that a scheduling frame period includes M time slots, wherein the first N time slots are broadcast time slots and the last (MN) time slots are service time slots; The broadcast time slot includes the synchronization channel and the broadcast channel. The synchronization channel occupies K subcarriers and is used for the receiving node to measure the signal time deviation. The broadcast channel occupies L subcarriers and is used to carry the public information broadcast to all other nodes. Each node occupies one broadcast time slot in turn to send the synchronization channel and the broadcast channel to all other nodes. The service time slot consists of multiple service channels, which are pure data channels without synchronization channels. The logical central node divides the OFDM time and frequency resources into different service channels according to the service needs of the ad hoc network and allocates them to the corresponding nodes for transmission. After receiving the service channel, the receiving node performs receiving timing compensation according to the time deviation value of the corresponding transmitting node recorded locally, and then demodulates and decodes.

4. The multi-carrier distributed network synchronization method based on time-division sub-band multiplexing according to claim 3, characterized in that: In step 2, the public information includes: a resource allocation table, a routing table and node status information.

5. The multi-carrier distributed network synchronization method based on time-division sub-band multiplexing according to claim 1, characterized in that: The method of using time-division sub-band multiplexing to decouple the synchronization channel from the service channel, deploying the synchronization channels of all nodes on fixed frequency domain sub-carrier resources in the broadcast time slot, and transmitting only the service channel in the service time slot without carrying the synchronization channel, specifically includes the following sub-steps: Step (1), in the broadcast time slot n=1, the logical central node 1 sends the synchronization channel and the broadcast channel, the ordinary nodes 2 to the ordinary nodes N measure the receiving time deviation according to the synchronization channel sent by the logical central node 1, and realize the receiving time slot synchronization alignment by adjusting the local receiving timing. After the receiving time slot synchronization alignment is completed, the ordinary nodes 2 to the ordinary nodes N receive the time deviation t of the time slot sent by the logical central node 1 21 ~t N1 Recorded in the local time offset table, where ordinary nodes 2 to ordinary nodes N have achieved receiving time slot synchronization alignment by adjusting the local receiving timing, record t 21 =0,t 31 =0,…,t N1 =0; Step (2), take n = n + 1, in broadcast time slot n, ordinary node n sends synchronization channel and broadcast channel based on the local receiving timing boundary, and other nodes measure the receiving time deviation {t jn |j=1,…,N,and j≠n}, and record it in the local time deviation table of each node; Step (3): Determine the loop traversal condition. If n < N, go to step (2); otherwise, go to step (4). Step (4), after steps (1) to (3), all nodes have completed the whole network synchronization based on the logical center node 1. The local time offset table recorded by each node includes: the time offset set {t nj |j=1,…,N,and j≠n},where n=1,…,N; Step (5): During the service time slot, the logical central node divides the OFDM time-frequency resources into different service channels as needed according to the service requirements of the ad hoc network and assigns them to the corresponding nodes for transmission. For the service channels, each node no longer sends a synchronization header. Step (6): The receiving node completes the reception timing compensation according to the timing offset information of other corresponding transmitting nodes maintained in the local timing offset table and then performs demodulation and decoding. Step (7): Determine whether the transmission in the service time slot of the current scheduling frame period has ended. If not, go to step (5); otherwise, go to the next scheduling frame period. In the next scheduling frame period, each node polls cyclically to send a synchronization channel and a broadcast channel in the broadcast time slot. Each node receives and measures the timing offset information of other nodes and updates the timing offset information to the local timing offset table of each node. During the service time slot, the receiving node completes the reception timing compensation according to the timing offset information of other corresponding transmitting nodes maintained in the local timing offset table and then performs demodulation and decoding.

6. The multi-carrier distributed network synchronization method based on time-division sub-band multiplexing according to claim 6, characterized in that: In step (6), the receiving node completes the reception timing compensation according to the timing offset information of other corresponding transmitting nodes maintained in the local timing offset table and then performs demodulation and decoding, which specifically includes the following sub-steps: Node j sends a service channel in the service time slot. After receiving the service channel sent by node j, node i first calculates the service channel according to the time offset information t in the local time offset table. ij Compensate for the receiving time deviation, and then perform demodulation and decoding, where i=1,…,N, j=1,…,N, and i≠j.

7. A multi-carrier distributed network synchronization system based on time-division sub-band multiplexing, comprising a computer device, characterized in that: A computer program is stored in the memory of the computer device, and when the computer program is loaded by the processor of the computer device, the method according to any one of claims 1 to 6 is executed.

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