CN109996342B - Channel resource allocation method and device in wireless self-organizing network - Google Patents
Channel resource allocation method and device in wireless self-organizing network Download PDFInfo
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- H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
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- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
- H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
- H04L1/1819—Hybrid protocols; Hybrid automatic repeat request [HARQ] with retransmission of additional or different redundancy
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- H—ELECTRICITY
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
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- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
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- H04W—WIRELESS COMMUNICATION NETWORKS
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- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality
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- H—ELECTRICITY
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- H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access, e.g. scheduled or random access
- H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
- H04W74/0808—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using carrier sensing, e.g. as in CSMA
- H04W74/0816—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using carrier sensing, e.g. as in CSMA carrier sensing with collision avoidance
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- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
- H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
The invention discloses a channel resource allocation method and equipment in a wireless self-organizing network. The first node sends out a trigger frame to the second node, and in the trigger frame, the first node sends out a frame to the first node in the earliest time slot by the second node with the largest signal-to-interference-and-noise ratio according to the signal-to-interference-and-noise ratio of the channel between the first node and the second node. The invention can improve the correct receiving probability of the data retransmission, can also improve the reliability of the data transmission, and effectively reduces the time delay of the data transmission.
Description
Technical Field
The invention relates to a channel resource allocation method in a wireless self-organizing network, and also relates to corresponding channel resource allocation equipment, belonging to the technical field of wireless communication.
Background
At present, for data packet retransmission in a wireless self-organizing network, a technical idea of cooperative retransmission is proposed, and the following three methods are specifically provided.
The first method is that when the destination node requires retransmission using NACK information, a neighbor node of the direct link detects packet exchange and retransmits a data packet when a data packet reception error (NACK is detected) occurs. The method does not consider the cause of packet transmission errors. If the packet reception error is not caused by poor channel quality of the direct link between the source node and the destination node, but is caused by other reasons (such as serious transmission error due to collision or interference), then the direct link is used to perform successful retransmission, and cooperative retransmission is unnecessary. In this method, moreover, the neighboring nodes that receive the DATA packet and NACK information of the source node automatically participate in the cooperative transmission, and the node selection problem is not considered. At this time, however, many nodes unnecessarily participate in cooperative retransmission, and thus a large amount of network resources will be wasted.
The second approach is to increase the throughput of the multi-hop network through retransmissions of neighboring nodes. However, the method selects the node closest to the final destination node as the receiving node of the current transmission, so that only one node is selected for data retransmission even if a plurality of nodes can perform cooperative transmission. It follows that the method simply selects one node to transmit the data packet to the destination node, and cannot guarantee that the node can correctly transmit the data packet to the destination node.
A third method combines packet retransmission with user collaboration. When the target node receives the DATA packet and requests retransmission through feedback information (i.e., NACK), the cooperative retransmission node performs self-selection by monitoring packet exchange information, i.e., those nodes that received the DATA frame and the NACK frame will automatically participate in retransmission. However, this method still has the following disadvantages:
(1) Those neighboring nodes that received the source node DATA packet and NACK information will automatically participate in the cooperative transmission. At this time, each cooperative retransmission node does not know the number of nodes participating in the cooperative transmission, and the transmission power of each cooperative retransmission node is selected by itself. Thus, each node may transmit data packets at a higher power (which is not actually needed), resulting in increased power consumption by the node. (2) It is assumed that the channel state information of the destination node to the cooperative retransmission node is the same as the channel of the cooperative retransmission node to the destination node, regardless of the consistency of the RF channel. However, in reality, in a wireless ad hoc network, the inconsistency of RF channels is more serious than in a cellular network, so that it is difficult to implement coherent combining at a receiving end and to ensure the gain of cooperative retransmission of a plurality of nodes.
Disclosure of Invention
The primary technical problem to be solved by the invention is to provide a channel resource allocation method in a wireless self-organizing network.
Another technical problem to be solved by the present invention is to provide a channel resource allocation device in a wireless ad hoc network.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
according to a first aspect of an embodiment of the present invention, there is provided a channel resource allocation method in a wireless ad hoc network, for a first node to allocate a time slot to a second node, the method including the steps of:
the first node sends out a trigger frame to the second node,
in the trigger frame, the first node transmits a frame to the first node at the earliest time slot by the second node with the largest signal-to-interference-and-noise ratio according to the signal-to-interference-and-noise ratio of the channel between the first node and the second node.
Wherein preferably the first node sets a signal-to-interference-and-noise ratio threshold value, divides the signal-to-interference-and-noise ratio of the channel between the first node and the second node into different areas,
the larger the signal-to-interference-and-noise ratio is, the earlier the second node corresponding to the signal-to-interference-and-noise ratio transmits the frame.
Wherein preferably, the time slots are divided into a contention phase and a feedback phase,
in the contention phase, the DIFS time is followed by a contention window,
in the feedback phase, the second node transmits the frame.
Wherein preferably, after DIFS of the time slot, the second node starts transmitting the frame after a feedback wait time,
the transmit wait time is determined by the signal-to-interference-and-noise ratio between the second node and the first node.
Preferably, if the time slot 1 to the time slot X are ordered from big to small according to the signal-to-interference-and-noise ratio, the transmission waiting time is:
Twait＝(m+n)×slot mini
dividing the total interval of the signal-to-interference-and-noise ratio into M sections, wherein each interval of the M sections is subdivided into N small sections;slot mini the minimum time slot unit in the self-organizing network is m=1, 2 … … M, n=1, 2 … … N, and the larger the signal-to-interference-and-noise ratio is, the smaller the corresponding M value is, and the smaller the corresponding N value is.
Wherein preferably, the contention window length is: CW= (M+N) x slot mini ，
Dividing the total interval of the signal-to-interference-and-noise ratio into M sections, wherein each interval of the M sections is subdivided into N small sections; slot mini Is the smallest unit of time slot in the ad hoc network.
Preferably, the trigger frame is used for limiting a time slot structure sent by the second node, and includes a feedback time slot number and a feedback time slot stipulation field.
Wherein preferably the slot structure further comprises SINR segmentation specifications.
Preferably, the first node sends a blank data packet notification frame and an NDP frame, and then sends the trigger frame.
Wherein preferably, the SINR segment specification field includes a segment number, a start-stop point of each segment, and a sub-segment number of each segment;
the feedback slot provisioning field includes provisions for contention window length, feedback time length, and feedback latency.
According to a second aspect of embodiments of the present invention, there is provided a channel resource allocation apparatus in a wireless ad hoc network, configured to allocate a time slot to a second node by a first node; wherein the device comprises a processor and a memory,
the memory has stored therein a computer program that, with the processor, causes the device to:
the first node sends out a trigger frame to the second node,
in the trigger frame, the first node sends a frame to the first node at the earliest time slot by the second node with the largest signal-to-interference-and-noise ratio according to the signal-to-interference-and-noise ratio of the channel between the first node and the second node.
The invention aims at the signal superposition problem caused by the fact that a destination node receives data of a plurality of source nodes simultaneously in a wireless self-organizing network; and the channel dynamic change between the destination node and the source node is large, the problem of channel reciprocity is not possessed, and an effective channel resource competition mechanism is provided. The invention can improve the correct receiving probability of data retransmission, improve the reliability of data transmission and effectively reduce the time delay of data transmission.
Drawings
Fig. 1 is a schematic diagram of an intelligent cooperative retransmission method of a wireless ad hoc network;
fig. 2 is a timing diagram of an intelligent cooperative retransmission method of a wireless ad hoc network;
fig. 3 is a flow chart of an intelligent cooperative retransmission method of a wireless ad hoc network;
fig. 4 is a flow chart of an intelligent cooperative retransmission method of a destination node;
fig. 5 is a schematic frame structure of a retransmission mode trigger frame according to the present invention;
fig. 6 is a schematic frame structure diagram of a feedback request trigger frame;
fig. 7 is a schematic diagram of a feedback slot structure in a feedback request trigger frame;
FIG. 8 is a schematic diagram of a frame structure of a feedback response frame;
fig. 9 is a schematic diagram of a frame structure of a retransmission initiation frame;
fig. 10 is a schematic frame structure of a cooperative retransmission ACK frame;
fig. 11 is a schematic diagram of the structure of a channel resource allocation apparatus (destination node).
Detailed Description
The technical contents of the present invention will be described in detail with reference to the accompanying drawings and specific examples.
Aiming at the data packet retransmission requirement in a wireless self-organizing network, the invention firstly provides an intelligent cooperative retransmission method. In the method, a destination node analyzes the cause of the error when the data packet is received in error, and an intelligent retransmission protocol is provided. The protocol designs a new NACK-Retransmission mode trigger frame with a field "Retransmission mode" (indicated by a bit: 0: source node Retransmission, 1: multiple nodes cooperative Retransmission). Thus, when the transmitting node or the adjacent node receives the NACK-Retransmission mode trigger frame, the correct transmission method can be automatically selected.
In addition, aiming at the mode of multi-node cooperative retransmission, in order to overcome the defects of the existing cooperative retransmission method, the invention designs a new cooperative retransmission protocol and a cooperative retransmission method, and the specific contents comprise: (1) New CQI (Channel Quality Indicator) and CSI (Channel Status Information) feedback request trigger frames are designed and sent by the destination node: in order to enable the destination node to determine the number of users participating in cooperative transmission and a cooperative transmission method, a CQI and CSI feedback request trigger frame is designed for feeding back CQI and CSI information and CQI information between the adjacent node and a source node (the node with the highest CQI between the adjacent node and the source node, which forwards ACK information to the source node) with better channel conditions (higher CQI/SINR); (2) A new CQI and CSI feedback response frame is designed and is used for feeding back CQI and CSI information by adjacent nodes; (3) And (3) selecting a cooperative retransmission node and designing a retransmission method: after receiving CQI and CSI feedback response frames of adjacent nodes, a destination node determines the number of optimal cooperative retransmission nodes, selects the optimal cooperative retransmission nodes, determines an optimal transmission method (comprising transmission power, a transmission weight value, a transmission time advance value and the like) of each node, and then transmits a cooperative retransmission starting frame containing the information; and (4) each cooperative retransmission node performs cooperative retransmission: after each node receives the cooperative retransmission initiation frame, according to the designated information in the retransmission initiation frame, the data packet is sent according to the designated parameters (including the transmitting power, the transmitting weighted value, the transmitting time advance value, etc.). Therefore, the data packet sent by each node has the maximum diversity combining gain at the destination node, so that the detection probability of the data packet is greatly improved; (5) transmission of ACK information: after the destination node receives the cooperatively retransmitted data packet correctly, it sends a "retransmission ACK frame" to a certain cooperatively retransmission node (the node and the source node have the best channel condition, also called a cooperative node), and then the cooperatively retransmission node forwards the "retransmission ACK frame" to the source node. The intelligent retransmission protocol can greatly improve the correct receiving probability of the retransmission data packet, thereby improving the overall performance of the network. The intelligent retransmission method is suitable for both the retransmission of the data packet segments and the retransmission of the data packet non-segments.
The self-adaptive cooperative retransmission method can adaptively select the following data retransmission modes according to the reasons of the data packet receiving errors: (1) retransmitting by the source node; or (2) a multi-node cooperative retransmission. Then, for the multi-node cooperative retransmission, the invention further provides a multi-node cooperative retransmission method, which comprises the following steps: (1) To determine which neighboring nodes can participate in cooperative retransmission, a CSI and CQI feedback request trigger frame is designed. Moreover, a feedback mechanism based on the SINR is defined in the feedback request trigger frame, so that those nodes with high SINR can feed back CSI and CQI information to the destination node preferentially. (2) And the destination node determines the number of nodes participating in the cooperative retransmission according to the feedback information of the nodes, and determines which nodes participate in the cooperative retransmission. Further, the transmit power, transmit weight, transmit Time Advance (TA) value, etc. of each cooperative retransmission node participating in the retransmission are determined according to a certain criterion, such as maximum transmit diversity, maximum ratio transmission, etc. (3) A cooperative retransmission initiation frame is designed, and the destination node sends the cooperative retransmission initiation frame to inform each cooperative retransmission node to retransmit the data packet. (4) And each cooperative retransmission node receives the cooperative retransmission starting frame and retransmits the data packet according to the information indicated in the frame, so that the maximum diversity gain can be obtained at the destination node. (5) After the destination node receives the retransmitted data packet correctly, ACK information is sent. The method can obtain the maximum diversity gain, and comprises the following specific steps:
step 1: RTS transmission
As shown in fig. 1, when the source node S competes for the channel use opportunity, a RTS (Request To Send) packet is transmitted to the destination node D. The RTS packet comprises information such as a sender address, a receiver address, data sending time, RTS sending power and the like.
Step 2: CTS transmission
When the destination node D receives the RTS packet, it sends a CTS (Clear To Send) packet to the source node S. The CTS packet includes information such as a transmitting end address, a receiving end address, a data transmission time, RTS transmission power, etc.
Step 3: DATA packet transmission
After the source node S receives the CTS packet, it sends a Data packet Data to the destination node D. The Data packet comprises information such as a transmitting end address, a receiving end address, data transmitting time, data packet transmitting power and the like.
Step 4: selecting retransmission mode according to data packet error reason
The destination node D receives the data packet from the source node S. If the destination node D correctly receives the Data packet Data, an ACK acknowledgement is sent to the source node S. If the destination node D does not correctly receive the data packet sent by the source node S, the intelligent cooperative retransmission method provided by the invention is adopted.
The following describes an intelligent cooperative retransmission method provided by the present invention with reference to fig. 2 to 10.
As shown in fig. 2 to 4, according to the received data packet from the source node S, the destination node D determines the cause of the error of the data packet, for example, whether the error is caused by the channel condition between the source node and the destination node, by using a conventional method. If not, i.e. the channel conditions between the source node and the destination node are good enough, selecting a source node retransmission mode (mode 1); if so, a cooperative retransmission mode (mode 2) is selected. And then forming a NACK retransmission mode trigger frame according to the selected retransmission mode, and sending out the NACK retransmission mode trigger frame. Then, the source node or the neighboring node adaptively selects a retransmission mode according to the retransmission mode trigger frame.
Whichever retransmission mode is used, the destination node transmits the frame in broadcast form, i.e., either the destination node's neighboring node or the source node can receive the frame, but in a different manner. After receiving the retransmission mode trigger frame, the adjacent node does not participate in cooperative retransmission if the transmission mode field in the frame is found to be "source node retransmission" (the value is 0); if the transmission mode is found to be "cooperative retransmission" (with a value of 1), actively participating in retransmission and preparing to receive a CSI feedback request trigger frame from the destination node.
Two retransmission modes are specifically described below.
Mode 1: source node retransmission (retransmission mode field value of 0)
The channel conditions between the source node and the destination node are good, except that the following factors cause reception errors of the data frame: (1) packet reception errors due to too low transmission power of the data frame, or (2) collisions occur when the target node receives the data. If the data frame is received by the reason (1), the destination node can inform the source node to increase the transmission power; if the data frame is received in error caused by the reason (2), the destination node informs the source node that the transmission power is not required to be increased during Retransmission through the NACK-Retransmission mode trigger frame.
Mode 2: neighboring node cooperative transmission (retransmission mode field value 1)
The channel condition between the source node and the destination node is relatively poor, on one hand, the source node cannot correctly unpack the packet even if transmitting for multiple times, and on the other hand, the source node cannot correctly demodulate NACK information sent by the destination node. At this time, the destination node needs to notify the neighboring node in the NACK-Retransmission mode trigger frame that cooperative Retransmission is needed.
Step 5: generating and transmitting retransmission mode trigger frame by destination node
And generating a retransmission mode trigger frame by the destination node according to the retransmission mode selected in the previous step.
In the invention, the novel NACK-Retransmission mode trigger frame structure (see figure 5) not only comprises frame control, duration, sending node address, destination node address, error data packet number, TP (transmit power) adjustment and P NACK Fields such as (transmit power used for transmitting NACK frames) and FCS (check), and further includes a "retransmission mode" field:
a retransmission mode (Retransmission Mode) field, which may be indicated by a bit, having two values, one 0, indicating the source node retransmission mode; one is 1, indicating a cooperative retransmission mode.
P NACK A field is a transmission power used when the destination node transmits a NACK frame.
In step 5A, a NACK-Retransmission mode trigger frame with a Retransmission mode field of 0 (i.e., the source node Retransmission mode) is sent, and the source node is notified of how to adjust the transmission power during data Retransmission through a transmission power adjustment information (TP adjustment Δp) field set in the Retransmission mode trigger frame. The destination node directly sends the retransmission mode trigger frame to the source node without cooperative retransmission, and the step 6 is entered.
And 5B, transmitting a Retransmission mode trigger frame with a Retransmission mode field of 1 (namely, a cooperative Retransmission mode), and when the transmitting node or the adjacent node receives the NACK-Retransmission mode trigger frame, automatically selecting a correct Retransmission method and entering the next step 7.
Step 6: receiving retransmission data packets from a source node
When the Retransmission mode in the NACK-Retransmission mode trigger frame is the Retransmission of the source node, the data packet is indicated to be retransmitted by the source node. At this time, the source node receives the NACK-Retransmission mode trigger frame, adjusts its transmission power according to the "transmission power" specified in the NACK-Retransmission mode trigger frame, and retransmits the data packet.
The destination node receives the data packet retransmitted by the source node, and sends an ACK acknowledgement frame after correctly receiving the data packet. When the neighbor node monitors the ACK frame, it discards the DATA frame it monitors.
Step 7: sending feedback request trigger frames
When the Retransmission mode in the NACK-Retransmission mode trigger frame is 'multi-node cooperative Retransmission', the data packet is not retransmitted by the source node to the requirement of correct demodulation of the destination node, and the adjacent node is required to be utilized for cooperative Retransmission.
In order to enable the destination node to determine the node participating in the cooperative retransmission and the cooperative retransmission parameters of each node, the invention designs a CQI and CSI feedback request trigger frame on one hand, so that the adjacent node can feed back channel information and is used for the destination node to select the node participating in the retransmission; on the other hand, a new mechanism for time-slotted competition channel resource is designed, so that adjacent nodes with higher CQI/SINR feed back the CQI and the CSI preferentially. With the design of the two aspects, the adjacent nodes with better channel conditions (i.e. higher CQI/SINR with the destination node) can be enabled to feed back the CQI and the CSI preferentially and the CQI information between the adjacent nodes and the source node (the node with the highest CQI with the source node can forward the ACK information to the source node), so that the destination node can select the adjacent nodes preferentially to participate in cooperative retransmission.
Specifically, as shown in fig. 2, the destination node first transmits a blank packet advertisement frame (NDP-a, null data packet announcement) and an NDP frame, and then transmits a feedback request Trigger frame (Trigger). The neighboring node then feeds back channel CSI and CQI information through a feedback frame (feedback frame). And finally, the destination node determines the node and the retransmission method which participate in the cooperative retransmission according to the CSI and the CQI information fed back by each adjacent node.
The feedback request Trigger frame (Trigger) specifies a feedback time slot structure, and specifically, as shown in fig. 6, includes fields such as frame control, duration, destination node address, check (FCS), and the like, as well as fields such as "feedback time slot number", "SINR segment specification", and "feedback time slot specification". Wherein, the SINR segmentation stipulation field comprises information such as a segmentation number M, a starting point and a stopping point of each segment, a sub-segment number N of each segment and the like; the "feedback slot provision" field includes information such as a contention window length, a feedback time length, and provision of a feedback wait time.
In order to enable the adjacent node with higher CQI/SINR to send preferentially, the invention provides a corresponding relation between CQI interval and feedback time slot in the time slot competition feedback mechanism based on CQI, as shown in figure 7. Since CQI is obtained from SINR, the two have a correspondence relationship, and thus, in the following description, only SINR will be described as an example.
In the feedback time slot structure shown in the figure, according to the SINR threshold value TH 0 ,TH 1 ……TH 5 (TH 0 ＞TH 1 …＞TH 5 ) From large to small, the feedback response frames of neighboring nodes are arranged to slot 1, slot 2, … …, slot X (x=6 in the figure). Each feedback slot is divided into a contention phase and a feedback phase. In the contention phase, DCF Interframe Space (DIFS) time is followed by a contention window. In the feedbackThe phase neighbor node sends feedback information.
After each frame DIFS, a feedback waiting time elapses, and a specific neighboring node to be fed back starts to transmit feedback information. The feedback waiting time is determined by the signal-to-interference-plus-noise ratio, SINR, between the neighboring node and the destination node.
Assuming that the total SINR is divided into M intervals, each SINR interval is further divided into N subintervals. At this time, the contention window length may be set as:
CW＝M×slot mini +N×slot mini (1)
assuming that the SINR value between the adjacent node to be fed back and the destination node is located in the nth subinterval of the mth interval of the SINR, in order for the node with high SINR to feed back CQI and CSI information preferentially, the feedback waiting time of the node is set to:
Twait＝(m+n)×slot mini (2)
dividing a total interval of the SINR into M sections according to the SINR, wherein each interval i in the intervals of the M sections is subdivided into N small sections; the threshold value Th of the signal-to-interference-and-noise ratio dividing M sections meets Th i,n ＝(Th i-1 -Th i )；slot mini Is the smallest unit of time slot in the ad hoc network. Where m=1, 2 … … M, n=1, 2 … … N, the larger the signal-to-interference-plus-noise ratio SINR, the smaller the value of M, the smaller the value of N (after modifying the formula, the larger the signal-to-interference-plus-noise ratio, the smaller the M, the shorter the feedback waiting time). Thus, as can be seen from equation (2), the greater the signal-to-interference-plus-noise ratio SINR, the smaller the feedback waiting time (i.e., the feedback waiting time of the node with high CQI is designed to be shorter), the easier it is to get the opportunity to send feedback information to the destination node. Therefore, the node with high CQI/SINR can feed back CQI and CSI information preferentially.
Those of ordinary skill in the art will appreciate that alternative methods are possible for formulas (1) and (2):
CW＝M×slot mini (1A)
Twait＝m×slot mini (2A)
in addition, if time slots 1 through X are ordered from small to large in terms of signal-to-interference-plus-noise ratio SINR (or CQI information) (i.e., SINR arrow in fig. 7 is reversed), i.e.Satisfy TH 0 ＜TH 1 …＜TH 5 If the SINR of a certain neighboring node is located in the nth sub-region of the mth region, the feedback waiting time may be calculated using the following formula:
Twait＝(M-m+1)×slot mini +(N-n+1)×slot mini (2B)
it can be seen that the neighbor node with the highest signal-to-interference-plus-noise ratio SINR with the destination node, the CQI-based slotted contention feedback mechanism, is assigned to slot 0, and the feedback wait time Twait is the shortest, so it is the earliest neighbor node to send feedback.
It should be noted that, the mechanism of time-slotted contention channel resource is not limited to the feedback request trigger frame provided by the present invention. The method can be applied to channel resource allocation in the wireless self-organizing network, so that nodes with good channel conditions allocate channel resources preferentially. When the mechanism of time-slotted competition channel resource provided by the invention is applied to channel resource allocation, the feedback waiting time can be the transmission waiting time of various control frames, and is not limited to the feedback waiting time.
Step 8: the destination node receives the feedback response frame
After receiving the feedback request trigger frame, the adjacent node synchronizes, estimates Channel State Information (CSI) and CQI of the adjacent node and the target node, calculates the time difference between the receiving timing RX and the transmitting timing TX, determines in which time slot to feed back the CQI and the CSI, and feeds back the waiting time.
Specifically, after receiving the CSI and CQI feedback request trigger frame, the neighboring node synchronizes with the frame header information of the CSI and CQI feedback request trigger frame, and estimates SINR/CQI and CSI information between the neighboring node and the destination node according to the frame header information. This is a conventional process and is not described in detail.
Based on the estimated SINR/CQI between the adjacent node and the destination node, the adjacent node may determine which time slot shown in fig. 7 the SINR of the adjacent node belongs to (i.e. the CQI and CSI should be fed back in that time slot, and send a feedback response frame) according to the feedback slot structure information (SINR segmentation rule, feedback slot rule, etc.) in the feedback request trigger frame, and also calculate the feedback waiting time according to equation (2).
As for calculation of the time difference between its reception timing RX and transmission timing TX, the neighbor node can determine the reception timing sta_rx_t by triggering the synchronization signal in the frame with the CSI and CQI feedback request transmitted from the destination node. Assuming that the transmission timing of the CSI and CQI feedback response frames transmitted by the neighboring node to the destination node is sta_tx_t, the time difference (sta_rx_txtimediference) between the reception timing RX and the transmission timing TX of the neighboring node is calculated as follows:
STA_RX_TXtimedifference＝STA_RX_t-STA_TX_t, (3)
the neighboring node transmits a time slot in its determined feedback response frame according to its calculated feedback waiting time, and feeds back SINR/CQI and CSI information between itself and the destination node, and SINR/CQI information between itself and the source node, to the destination node using the feedback response frame (as shown in fig. 8).
The feedback response frame, as shown in fig. 8, contains the following information: destination node address, duration, retransmission node address, CQI information and CSI information, CQI information with source node, time difference between reception timing RX and transmission timing TX. The retransmission node address is the address of the adjacent node sending the feedback response frame; the CQI information and the CSI information are the CQI and the CSI information between the adjacent node transmitting the feedback response frame and the destination node estimated by the adjacent node; CQI information with the source node refers to CQI information with the source node estimated by neighboring nodes transmitting the feedback response frame.
The destination node receives the feedback response frame from the adjacent node according to the feedback time slot structure specified when the destination node generates the feedback request trigger frame.
Step 9: the destination node selects a cooperative retransmission node, determines a cooperative retransmission method and forms a retransmission starting frame
In this step, the destination node determines the nodes involved in retransmission, determines the cooperative retransmission method, and determines the transmission timing advance value of each node.
The destination node determines the optimal cooperative retransmission node and retransmission method (including the transmission power, the transmission weighting coefficient, etc. during retransmission of each node) according to the information in the feedback response frame of each node and in combination with the size of the retransmission data packet, as shown in fig. 9.
The cooperative retransmission method may be a cooperative transmission method in a conventional wireless communication system (such as an LTE system), including a maximum ratio transmission method, a maximum space diversity transmission method, and the like.
For example, assume that L nodes are selected to participate in cooperative transmission, and a conventional maximum ratio transmission method is adopted. Assume that the channel matrix (CSI) between L nodes to the destination node can be expressed as:
wherein alpha is rd,l And h rd,l Representing the large scale path loss and channel coefficients, respectively, of the collaboration link l. When the maximum ratio transmission method is adopted, the transmission weight vector should be:
thus, the destination node may determine the transmit weighting coefficients and transmit power for each cooperative retransmission node according to equation (5). Conventional methods may be employed herein.
The procedure by which the destination node determines the Timing Advance (TA) value of each cooperative retransmission node at the time of retransmitting the data packet is further described below.
When a plurality of cooperative retransmission nodes retransmit data packets to a destination node at the same time, the time for the signals sent by different cooperative retransmission nodes to reach the destination node is required to be aligned and added in phase, so that the destination node can coherently combine retransmission signals from different nodes to achieve the maximum combining gain. Therefore, the destination node needs to appropriately control the Timing Advance (TA) value of each cooperative retransmission node in retransmitting the data packet, so that signals of different STAs arrive at the destination node at the same time. That is, the destination node notifies each cooperative retransmission node of a Timing Advance (TA) value of the retransmission of the data packet by each cooperative retransmission node.
First, after receiving the CQI and CSI feedback response frame of each node, the destination node estimates CSI and SINR/CQI between each node and the preamble of the frame header, and determines the receiving timing d_sta_rx_t according to the synchronization signal in the frame header. Assume that the transmission timing of the destination node to transmit the feedback request Trigger frame (Trigger) is d_sta_tx_t. At this time, the time difference (d_sta_rx_ TX time difference) between the reception timing d_sta_rx_t and the transmission timing d_sta_tx_t of the destination node is calculated as:
D_STA_RX_TX time difference＝D_STA_RX_t-D_STA_TX_t (6)
according to equations (3) and (6), the method for determining the transmission Timing Advance (TA) value of the retransmission packet of each cooperative retransmission node is as follows:
TA＝(STA_RX_t-STA_TX_t)+(D_STA_RX_t-D_STA_TX_t) (7)
in the cooperative retransmission method provided by the invention, because the channel quality between the destination node and the source node is relatively poor, the source node may not receive the ACK information sent by the destination node. Therefore, the destination node needs to determine a node with the best channel quality with the source node among the nodes participating in the cooperative retransmission, and the node forwards ACK information of the destination node to the source node. To achieve this, the destination node may determine the node with the best channel quality with the source node according to the SINR/CQI information fed back by each node between itself and the source node.
Step 10: the destination node sends a cooperative retransmission initiation frame to the selected retransmission node
At this time, the source node may not necessarily receive the retransmission mode trigger frame information of the target node, and the target node needs to determine the cooperative retransmission node with the highest CQI with the source node according to the feedback information of each cooperative retransmission node, and notify the node to relay the source node to retransmit the erroneous data packet in the cooperative retransmission start frame, and after the correct retransmission is finished, the target node further relay the source node to have correctly retransmitted the data packet.
Finally, in order for each cooperative retransmission node to retransmit the data packet to the destination node, the destination node sends a cooperative retransmission initiation frame to each cooperative retransmission node, as shown in fig. 9. The cooperative retransmission initiation frame includes the following fields: source node address, destination node address, retransmission method of cooperative retransmission node TX1, retransmission method of node TX2, …, retransmission method of cooperative retransmission node P, address of ACK forwarding node, packet transmission time, retransmission duration, etc. The retransmission method of the cooperative retransmission node comprises the following steps: the address of each cooperative retransmission node, its transmission power, its transmission weighting coefficient and its transmission timing advance value TA.
The destination node selects a node which can be reached after 2 hops between the destination node and the source node according to the feedback response frame received first by the destination node as a cooperative retransmission node, and then the destination node takes the addresses of the selected cooperative retransmission nodes as the addresses of the cooperative retransmission nodes in a cooperative retransmission starting frame. In short, the destination node selects the 2-hop node received earlier as the cooperative retransmission node according to the time sequence of receiving the feedback response frame, and the address of the corresponding cooperative retransmission node is listed in the cooperative retransmission starting frame.
The transmitting power and the transmitting weighting coefficient of each cooperative retransmission node are calculated by the CSI information in the feedback response frame sent by the destination node through the selected cooperative retransmission node, for example, calculated by using formula (5).
The transmit timing advance value TA is calculated by the destination node in step 9 according to equation (7).
Step 11: the destination node sends the cooperative retransmission ACK frame after correctly demodulating the retransmission data packet
After each adjacent node receives the cooperative retransmission starting frame sent by the destination node, judging whether the node participates in retransmission or not according to the cooperative retransmission node address in the cooperative retransmission mode triggering frame. If the cooperative retransmission starting frame contains the address of the node, the node is used as a cooperative retransmission node to participate in retransmission; if the address of the node is not contained in the cooperative retransmission initiation frame, the node does not participate in the cooperative retransmission.
If the cooperative retransmission node is judged, the cooperative retransmission node further retransmits the data packet to the destination node according to the node transmitting power, the transmitting weighting coefficient, the transmitting timing advance value and the like specified in the cooperative retransmission start frame.
And finally, the destination node receives and demodulates the data packet to obtain the cooperative retransmission. If the destination node correctly demodulates the cooperatively retransmitted data packet, the cooperatively retransmitted ACK information is transmitted to the ACK-forwarding node (i.e., the node with the best channel quality selected in step 9).
The cooperative retransmission ACK frame structure is shown in fig. 10, and includes an address of an ACK forwarding node, frame control, duration, transmitting node address, destination node address, erroneous packet number, and FCS. The address of the ACK forwarding node is the address of the node with the best channel quality selected by the destination node in step 9.
And when the node appointed in the cooperative retransmission ACK receives the cooperative retransmission ACK, the ACK forwarding node forwards the cooperative retransmission ACK to the source node, and the source node is indicated that the data packet is successfully retransmitted to the destination node.
The specific structure of the channel resource allocation apparatus as the destination node 100 is described below. Fig. 11 is a schematic structural diagram of the channel resource allocation apparatus. The device comprises a processor, a memory, an interface and the like. The memory stores a computer program for enabling the device to execute the processes of the steps 1 to 11 together with the processor, thereby realizing the intelligent cooperative retransmission method of the wireless self-organizing network.
In the invention, the retransmission mode trigger frame, the feedback request trigger frame, the feedback response frame, the cooperative retransmission starting frame and the cooperative retransmission ACK frame belong to control frames, and the conventional interfaces used by the control frames in the wireless self-organizing network are used for transmission. In addition, the retransmission data frames are transmitted using a conventional interface used by control frames in the wireless ad hoc network.
The invention adds additional CQI acquisition flow (including CQI feedback request trigger frame, CQI feedback response frame, cooperative retransmission start frame, etc.), which brings the following technical performance gains:
(a) In the selection of the cooperative retransmission nodes, the node with the best channel condition is selected, and the optimal node number and node are determined. In addition, an optimal transmission method (including transmission power, transmission weighting coefficient, transmission time advance, and the like) is determined for each node. Thus, the signals retransmitted by all nodes can reach the destination node simultaneously, and the maximum merging gain is ensured. Therefore, the invention greatly improves the correct receiving probability of the data retransmission and improves the reliability of the data transmission.
(b) In the existing cooperative transmission method, retransmission signals of all nodes are difficult to reach a destination node at the same time, and coherent combination is difficult to realize. Therefore, the transmission performance of the data packet is difficult to ensure. In contrast, the invention greatly improves the correct receiving probability of the data retransmission and improves the reliability of the data transmission although adding some signaling overhead. Thus, the method effectively reduces the time delay of data transmission by ensuring the reliability of the data transmission.
In a word, compared with the prior art, the invention greatly improves the correct receiving probability of the data retransmission and improves the reliability of the data transmission. Therefore, the time delay of data transmission is effectively reduced, and the method is more suitable for time delay sensitive services.
The method and the device for allocating channel resources in the wireless self-organizing network provided by the invention are described in detail. Any obvious modifications to the present invention, without departing from the spirit thereof, would constitute an infringement of the patent rights of the invention and would take on corresponding legal liabilities.
Claims (9)
1. A channel resource allocation method in wireless self-organizing network is used for allocating time slots to a second node by a first node, and is characterized in that:
the first node sends out a trigger frame to the second node, the first node is a destination node, the second node is a neighboring node of the first node,
in the trigger frame, the first node specifies that a frame is transmitted to the first node at the earliest time slot by the second node with the largest signal-to-interference-and-noise ratio according to the magnitude of the signal-to-interference-and-noise ratio of the channel between the first node and the second node,
the first node sets a signal-to-interference-and-noise ratio threshold value, divides the signal-to-interference-and-noise ratio of a channel between the first node and the second node into different areas, and the second node corresponding to the signal-to-interference-and-noise ratio sends the frame in an earlier time slot as the signal-to-interference-and-noise ratio is larger;
the time slot is divided into a contention phase and a feedback phase, wherein the contention phase is firstly the DIFS time and then the contention window, and the second node transmits the frame in the feedback phase;
after the DIFS time of the slot, the second node starts transmitting the frame after a feedback waiting time, which is determined by the signal-to-interference-and-noise ratio between the second node and the first node.
2. The channel resource allocation method according to claim 1, wherein:
if time slot 1 to time slot X are ordered from large to small in signal-to-interference-and-noise ratio, the feedback waiting time is:
Twait＝(m+n)×slot mini
dividing the total interval of the signal-to-interference-and-noise ratio into M sections, wherein each interval of the M sections is subdivided into N small sections; slot mini The minimum time slot unit in the self-organizing network is m=1, 2 … … M, n=1, 2 … … N, and the larger the signal-to-interference-and-noise ratio is, the smaller the corresponding M value is, and the smaller the corresponding N value is.
3. The channel resource allocation method according to claim 2, wherein:
the contention window length is: CW= (M+N) x slot mini ，
Dividing the total interval of the signal-to-interference-and-noise ratio into M sections, wherein each interval of the M sections is subdivided into N small sections; slot mini Is the smallest unit of time slot in the ad hoc network.
4. The channel resource allocation method according to claim 1, wherein:
the trigger frame is used for limiting a time slot structure sent by the second node, and comprises the number of feedback time slots and a feedback time slot stipulation field.
5. The channel resource allocation method according to claim 4, wherein:
the slot structure further includes a SINR segment specification field.
6. The channel resource allocation method according to claim 5, wherein:
and the first node firstly transmits a blank data packet notification frame and an NDP frame, and then transmits the trigger frame.
7. The channel resource allocation method according to claim 6, wherein:
the SINR segmentation stipulated field comprises the segmentation number, the starting point of each segment and the number of sub-segments of each segment;
the feedback slot provisioning field includes provisions for contention window length, feedback time length, and feedback wait time.
8. A channel resource allocation apparatus in a wireless ad hoc network for a first node to allocate time slots to a second node, comprising a processor and a memory;
the memory has stored therein a computer program that, with the processor, causes the device to:
the first node sends out a trigger frame to the second node, the first node is a destination node, the second node is a neighboring node of the first node,
in the trigger frame, the first node sends a frame to the first node at the earliest time slot by the second node with the largest signal-to-interference-and-noise ratio according to the signal-to-interference-and-noise ratio of the channel between the first node and the second node;
the processor enables the first node to set a signal-to-interference-and-noise ratio threshold value, divides the signal-to-interference-and-noise ratio of a channel between the first node and the second node into different areas, and the second node corresponding to the signal-to-interference-and-noise ratio sends the frame in an earlier time slot as the signal-to-interference-and-noise ratio is larger;
the time slot is divided into a contention phase and a feedback phase, wherein the contention phase is firstly the DIFS time and then the contention window, and the second node transmits the frame in the feedback phase;
the processor causes the second node to begin transmitting the frame after a DIFS time of the slot by a feedback wait time determined by the signal-to-interference-and-noise ratio between the second node and the first node.
9. The channel resource allocation apparatus according to claim 8, wherein:
the trigger frame is used for limiting a time slot structure sent by the second node and comprises feedback time slot number, SINR segmentation regulation and feedback time slot regulation fields.
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