CN107801209B - Wireless ad hoc network communication method and node - Google Patents
Wireless ad hoc network communication method and node Download PDFInfo
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- CN107801209B CN107801209B CN201610804973.XA CN201610804973A CN107801209B CN 107801209 B CN107801209 B CN 107801209B CN 201610804973 A CN201610804973 A CN 201610804973A CN 107801209 B CN107801209 B CN 107801209B
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Abstract
The invention provides a wireless ad hoc network communication method and a node, and the method can comprise the following steps: the node sends a signal to a receiving node in a current time slot, wherein a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and the length of the guard interval is greater than or equal to the sum of the round-trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network. The embodiment of the invention can reduce the frame exchange overhead in the wireless ad hoc network.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a wireless ad hoc network communication method and a node.
Background
In the existing wireless ad hoc network System, when there is no Global Positioning System (GPS) or beidou Positioning System, the synchronization method is mostly a master-slave synchronization method based on frame exchange, so as to achieve transmission synchronization of the whole network, i.e. solve the problem of overlapping and collision of transceiving between nodes, so as to meet the transmission requirement of the wireless ad hoc network. The master-slave synchronization method based on frame exchange mainly requests a synchronization node to initiate a clock synchronization request frame, and a time service node receives and sends a clock response frame added with a timestamp to the request synchronization node; and after receiving the request synchronization node, obtaining a clock difference value through simple operation, and calibrating a local clock according to the clock difference value to realize synchronization. The synchronization method based on frame exchange needs a large number of request and response frames for synchronization, and particularly in a scene with a large number of nodes, the overhead for synchronization is not negligible. Therefore, the problem of high frame exchange overhead exists in the existing wireless ad hoc network.
Disclosure of Invention
The invention aims to provide a wireless ad hoc network communication method and a node, which aim to solve the problem of high frame exchange overhead in a wireless ad hoc network.
In order to achieve the above object, an embodiment of the present invention provides a wireless ad hoc network communication method, including:
the node sends a signal to a receiving node in a current time slot, wherein a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and the length of the guard interval is greater than or equal to the sum of the round-trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
Optionally, the length of the guard interval is greater than or equal to a preset time delay, where the preset time delay is a sum of a round-trip time delay of the wireless ad hoc network, a transceiver switching time delay of a node in the wireless ad hoc network, and a maximum time delay extension in the wireless ad hoc network; or
The current time slot comprises a cyclic prefix, the length of the cyclic prefix is greater than or equal to the maximum delay spread in the wireless ad hoc network, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
Optionally, the guard interval is located at the beginning or the end of the current time slot, or the guard interval is located in the middle between the current time slot and the adjacent time slot.
Optionally, the node sends, in the current time slot, synchronization information used for the receiving node to perform receiving synchronization so as to determine a time slot starting time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
Optionally, the method further includes:
the node selects a node with the earliest timing from the neighbor nodes as a reference node, and takes the time slot starting time of the sending signal of the reference node as the starting time of the sending time slot of the node.
Optionally, the selecting, by the node, a node with the earliest timing from the neighboring nodes as a reference node includes:
the node receives broadcast information sent by neighbor nodes, the broadcast information sent by each neighbor node comprises synchronous information, and the synchronous information is used for receiving and synchronizing the nodes so as to determine the starting time of a time slot for receiving signals;
and the nodes carry out receiving synchronization through the synchronization information sent by each neighbor node, and select the node with the earliest timing as a reference node according to the synchronization result.
Optionally, there is only one node at the highest synchronization level in the wireless ad hoc network, or there are multiple nodes at the node at the highest synchronization level in the wireless ad hoc network, where the multiple nodes send synchronization.
Optionally, the method further includes:
and the node receives a signal sent by the receiving node in another time slot, wherein a guard interval exists between the time slot and the adjacent time slot, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
An embodiment of the present invention further provides a wireless ad hoc network node, including:
a sending module, configured to send a signal to a receiving node in a current time slot, where a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and a length of the guard interval is greater than or equal to a sum of a round-trip delay of the wireless ad hoc network and a transceiver conversion delay of a node in the wireless ad hoc network.
Optionally, the length of the guard interval is greater than or equal to a preset time delay, where the preset time delay is a sum of a round-trip time delay of the wireless ad hoc network, a transceiver switching time delay of a node in the wireless ad hoc network, and a maximum time delay extension in the wireless ad hoc network; or
The current time slot comprises a cyclic prefix, the length of the cyclic prefix is greater than or equal to the maximum delay spread in the wireless ad hoc network, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
Optionally, the guard interval is located at the beginning or the end of the current time slot, or the guard interval is located in the middle between the current time slot and the adjacent time slot.
Optionally, the node sends, in the current time slot, synchronization information used for the receiving node to perform receiving synchronization so as to determine a time slot starting time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
Optionally, the node further includes:
and the selection module is used for selecting the node with the earliest timing from the neighbor nodes as the reference node and taking the time slot starting moment of the sending signal of the reference node as the starting moment of the self sending time slot.
Optionally, the selecting module includes:
the receiving unit is used for receiving broadcast information sent by neighbor nodes, the broadcast information sent by each neighbor node comprises synchronous information, and the synchronous information is used for receiving and synchronizing the receiving nodes so as to determine the starting time of a time slot of a received signal;
and the selection unit is used for carrying out receiving synchronization through the synchronization information sent by each neighbor node and selecting the node with the earliest timing as a reference node according to a synchronization result.
Optionally, there is only one node at the highest synchronization level in the wireless ad hoc network, or there are multiple nodes at the node at the highest synchronization level in the wireless ad hoc network, where the multiple nodes send synchronization.
Optionally, the node further includes:
and the receiving module is used for receiving a signal sent by the receiving node in another time slot, wherein a guard interval exists between the time slot and the adjacent time slot, and the length of the guard interval is greater than or equal to the sum of the round-trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
The technical scheme of the invention at least has the following beneficial effects:
in the embodiment of the invention, a node sends a signal to a receiving node in a current time slot, wherein a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and the length of the guard interval is greater than or equal to the sum of the round-trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network. Therefore, the problems of overlapping and collision of transceiving between nodes can be avoided through the guard interval of the time slot, so that the problems of overlapping and collision of transceiving between nodes do not need to be avoided through frame exchange as in the prior art, and the frame exchange overhead in the wireless ad hoc network is reduced.
Drawings
Fig. 1 is a flowchart illustrating a wireless ad hoc network communication method according to an embodiment of the present invention;
fig. 2 is a schematic diagram of timeslot transmission according to an embodiment of the present invention;
fig. 3 is a schematic diagram of another timeslot transmission according to an embodiment of the present invention;
fig. 4 is a schematic diagram of another timeslot transmission provided in the embodiment of the present invention;
fig. 5 is a diagram illustrating a superframe structure according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a timeslot structure according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a symbol structure according to an embodiment of the present invention;
fig. 8 is a diagram illustrating another superframe structure according to an embodiment of the present invention;
fig. 9 is a schematic diagram of another timeslot structure according to an embodiment of the present invention;
fig. 10 is a schematic diagram of another timeslot transmission according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a wireless ad hoc network node according to an embodiment of the present invention;
fig. 12 is a schematic structural diagram of another wireless ad hoc network node according to an embodiment of the present invention;
fig. 13 is a schematic structural diagram of another wireless ad hoc network node according to an embodiment of the present invention;
fig. 14 is a schematic structural diagram of another wireless ad hoc network node according to an embodiment of the present invention;
fig. 15 is a schematic structural diagram of another wireless ad hoc network node according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The embodiment of the invention can be applied to a wireless ad hoc network, wherein the wireless ad hoc network is formed by nodes, is an autonomous and multi-hop network, has no fixed infrastructure in the whole network, and can provide mutual communication among the nodes under the condition that the existing network infrastructure (such as a base station and an Access Point (AP)) cannot be utilized or is inconvenient to utilize. And in the wireless ad hoc network, because the transmitting power and the wireless coverage range of the nodes are limited, two nodes which are far away can carry out packet forwarding by means of other nodes if communication is carried out, and thus a wireless multi-hop network is formed between the nodes. The mobile nodes in the wireless ad hoc network have routing and packet forwarding functions, and can form any network topology through wireless connection. The wireless ad hoc network can be used as a single network to independently work, and can also be accessed to the existing network in the form of a terminal subnet, such as an Internet network and a cellular network. In addition, the node described in the embodiment of the present invention may be any node in a wireless ad hoc network, and is not limited to a specific type thereof.
Referring to fig. 1, an embodiment of the present invention provides a wireless ad hoc network communication method, as shown in fig. 1, including the following steps:
101. the method comprises the steps that a node sends a signal to a receiving node in a current time slot, wherein a Guard Period (GP) exists between the current time slot and a time slot adjacent to the current time slot, and the length of the GP is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
The current time slot may be any time slot in the wireless ad hoc network, and the adjacent time slot may be a next time slot adjacent to the current time slot or a previous time slot adjacent to the current time slot. For example: if the current time slot is the 0 th time slot in a certain frame, the adjacent time slot is the 1 st time slot, or if the current time slot is the 1 st time slot in a certain frame, the adjacent time slot is the 0 th or the 2 nd time slot.
In addition, the node may be any node in a wireless ad hoc network, and the time slot may be any time slot in the wireless ad hoc network. Therefore, the GP can be contained between any two time slots before and after through the steps, and the length of any GP is larger than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
The round trip delay of the wireless ad hoc network may be a round trip delay corresponding to a single-hop maximum coverage distance in the wireless ad hoc network, or may be a maximum round trip delay of the wireless ad hoc network, or may be a round trip delay of a nominal coverage range in the wireless ad hoc network, which may be preconfigured, or set when designing the network, or may be set according to a network transmission requirement, which is not limited in the embodiment of the present invention.
The embodiment of the invention can realize that the GP is arranged between the two time slots, thereby avoiding the problems of overlapping and conflict of receiving and transmitting between the nodes and reducing the frame exchange expense in the wireless ad hoc network. That is, special frame exchange operation is not required, and frame structure or time slot structure is specially designed and some other limitations are met, so that overlapping and collision of transceiving between nodes are not caused, and the transmission requirement of the ad hoc network is met.
Optionally, the length of the protection interval is greater than or equal to a preset time delay, where the preset time delay is a sum of a round trip delay of the wireless ad hoc network, a transceiver switching delay of a node in the wireless ad hoc network, and a maximum delay spread in the wireless ad hoc network.
In this embodiment, the maximum delay spread of the wireless ad hoc network may be a maximum delay spread allowed in the wireless ad hoc network, for example: maximum multipath delay spread. In this embodiment, the problem of overlapping and collision of transceiving between nodes can be avoided by the length of the GP. For example: as shown in FIG. 2, node A and node B are adjacent to each otherAt node B, the transmission timing of A is ahead of that of B, and the propagation delay (slot) between the two is tau1. Since the principle of selecting the timing reference node by each node can be the most advanced (earliest) timing node in all the neighbor nodes, the timing difference τ between the two nodesd1≤τ1I.e. taud1Maximum τ1Where B may select at least A as the timing reference node, at which time τd1＝τ1. As shown in FIG. 2, node A transmits in time slots indicated by black and node B transmits in time slots indicated by gray, the shaded portion being the transmit-receive overlap at node A, with a time duration τd1+τ1≤2τ1(ii) a 2 τ if communication between any two nodes one hop away in an ad hoc network is considered1RTT, where RTT is the round trip delay of the wireless ad hoc network, for example: and the self-organized network system has the round trip delay corresponding to the maximum single-hop coverage distance. For example: maximum multipath time delay expansion of tau in wireless ad hoc network systemmaxThe receiving and transmitting conversion time delay of the node is tauRTThen GP length T of each time slotGPThe following conditions should be satisfied:
TGP≥τd1+τ1+τmax+τRT≥RTT+τmax+τRT
the length of the GP can make the node a transmit and receive without aliasing and interference, as shown in fig. 2, the receiving of the time slot n at the node a overlaps with the transmitting of the time slot n +1, as shown by the shaded portion of the node a, the shaded portion is required to fall within the GP range of the time slot n in order to realize the no aliasing of the transmit and receive; at the node B, the shaded portion overlaps with the transmission and reception at the node B, and the time length thereof is as follows:
i.e. the transceiving overlap of B is smaller than the length of the shaded part in node a, taking into account the maximum delay spread in the system as taumaxThe receiving and transmitting conversion time delay of the node is tauRTSelecting TGP≥RTT+τmax+τRTThen transmission and reception are less at node BThere will be no aliasing and interference. It should be noted that for simplicity, τmaxAnd τRTNot shown in the figure.
By the above description, when the condition T is satisfiedGP≥RTT+τmax+τRTIn time, the condition of receiving and transmitting aliasing and interference can not occur in the communication between the nodes A and B of any mutually adjacent nodes.
Optionally, the current timeslot includes a cyclic prefix, a length of the cyclic prefix is greater than or equal to a maximum delay spread in the wireless ad hoc network, and a length of the guard interval is greater than or equal to a sum of a round trip delay of the wireless ad hoc network and a transceiver conversion delay of a node in the wireless ad hoc network.
In this embodiment, the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceive delay of the node in the wireless ad hoc network, so that in some systems, a guard time is added at the beginning of a timeslot to cover τmaxFor example, in a system using Orthogonal Frequency Division Multiplexing (OFDM) modulation, a Cyclic Prefix (CP) is added to each symbol, and the length of the CP may be TCPSatisfy TCP≥τmaxAt this time, the GP length T of each slotGPShould satisfy TGP≥RTT+τRTI.e., without covering τmaxThis case is equivalent to dividing the guard interval between slots into two parts, one part being the GP between slots, e.g., the GP at the end of the current slot (previous slot) or the GP of the switch, and the other part being the CP of the adjacent slot (next slot).
In addition, the length of the cyclic prefix may be greater than or equal to the maximum multipath delay spread in the wireless ad hoc network.
Namely TCPSatisfy TCP≥τmax。
It should be noted that, for the illustration of the length of GP, only two nodes are used as an example to illustrate a condition that no transmission/reception aliasing or interference occurs in communication between any two nodes. In addition, it is necessary to considerIs considered to satisfy the above-mentioned TGP≥RTT+τmax+τRTIf any node a is receiving any of its neighbors B, C, then no inter-received signal aliasing or interference occurs. As shown in fig. 3, any node a needs to receive the time slot signal of any node C, B successively, for example, the time slot n-1 receives the signal of the node C, the time slot n receives the signal of the node B, and the time slot n +1 needs to receive the signal of the node C. Suppose node A advances timing with B by τd1C with timing advanced by A and by τd2(ii) a The propagation delay between node A and node B is τ1The propagation delay between node A and node C is τ2Note that, for simplicity, τmaxAnd τRTNot shown in the figure.
From the previous explanation of FIG. 2, it must be τd1≤τ1、τd2≤τ2(ii) a The satisfaction of T at GP is explained in detail in the previous figuresGP≥RTT+τmax+τRTWhen the signals are transmitted and received at any node, no aliasing occurs, that is, for the time T1 in FIG. 3, the signal falls at least in the GP of the signal of the time slot n-1 transmitted by the node C received by the node A, and the time T3 falls at least in the GP of the signal of the time slot n transmitted by the node B received by the node A.
Hereinafter, it is only required to prove that the start time T2 of the node a in receiving the time slot n of the node B is greater than or equal to T1, that is, T2 is after T1, then T2 certainly falls in GP of the time slot n-1 signal, or after GP of the time slot n-1 signal, that is, the node a does not generate overlapping and interference on the reception of the node C, B in sequence; similarly, it is only necessary to prove that the start time T4 of the node a in receiving the slot n +1 of the node C is greater than or equal to T3, that is, T4 is after T3, then T4 certainly falls in GP of the slot n signal or after GP of the slot n signal, that is, the node a does not overlap and interfere with the reception of the successive node B, C.
And T1 is T + Td2+Ts，T2＝T+τd1+τd2+Ts+τ1，T2-T1＝τd1+τ1More than or equal to 0, T2 more than or equal to T1.
Since T3 is T +2Ts+τd2，T4＝T+2Ts+τ2，T4-T3＝τ2-τd2More than or equal to 0, T4 more than or equal to T3.
That is, the aforementioned T is satisfiedGP≥RTT+τmax+τRTIn the process, the communication between the nodes A and B of any adjacent nodes does not generate receiving and transmitting aliasing and interference, and the receiving of any adjacent node by any node A does not generate aliasing and interference.
Optionally, the guard interval is located at the beginning or the end of the current time slot, or the guard interval is located between the current time slot and the adjacent time slot.
In this embodiment, it can be realized that the GP existing between the two slots may be the end or the beginning of the current slot, so that the GP existing between the two slots can be realized. Wherein the end or the beginning may be a portion of the time slot that is GP. In addition, the guard interval located between the current timeslot and the adjacent timeslot may be, and the guard interval may be a special timeslot between the current timeslot and the adjacent timeslot, that is, the special timeslot is a guard interval between the current timeslot and the adjacent timeslot.
Optionally, the node sends, in the current time slot, synchronization information used for performing receiving synchronization by the receiving node to determine a time slot starting time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
In this embodiment, the above-mentioned synchronization information used by the receiving node to perform receiving synchronization to determine the starting time of the timeslot of the received signal may be a certain amount of known information, for example: a Preamble (Preamble). That is, when a node transmits a signal in a time slot, a certain amount of known information is transmitted in the time slot, so that a receiving node performs receiving synchronization according to the known information to determine the time slot starting time of the received signal.
In addition, the synchronization information may be sent in the first time slot or 0 th time slot in the frame to which the time slot belongs, or of course, the synchronization information may be sent in each time slot, so that the receiving node performs reception synchronization according to the known information to determine the time slot starting time of the received signal. So as to realize that the structure of the time slot or the frame has certain characteristics, so that the receiving node can complete the receiving synchronization.
Optionally, the method further includes:
the node selects a node with the earliest timing from the neighbor nodes as a reference node, and takes the time slot starting time of the sending signal of the reference node as the starting time of the sending time slot of the node.
In this embodiment, the node may select a node with the earliest timing from among neighboring nodes as the reference node, and use a start time of a slot in which a transmission signal of the reference node is received as a start time of its own transmission slot. For example: as shown in fig. 4, it is assumed that node a is the node whose timing determined by the time when node B receives one superframe is the earliest and determines it to be its own timing reference node. Let the transmission time of A be T and the propagation delay of the two be tau1B determines the start time of the received time slot n-1 of the node A to be T + tau through the receiving synchronization1If B carries out time slot transmission, the time of time slot transmission is T + tau1,T+τ1+Ts,T+τ1+2Ts,., wherein TsIs the time length of one slot.
In addition, the node having the earliest timing may be a node, among the neighbor nodes, which receives a signal transmitted in a super frame first by the node. For example: the node is arranged at 4 neighbor nodes and neighbor nodes 1 to 4, wherein the node receives signals sent by the neighbor node 1, the neighbor node 2, the neighbor node 3 and the neighbor node 4 in a superframe in sequence, and then the neighbor node 1 can be used as a reference node.
Optionally, the selecting, by the node, a node with the earliest timing from the neighboring nodes as a reference node includes:
the node receives broadcast information sent by neighbor nodes, the broadcast information sent by each neighbor node comprises synchronous information, and the synchronous information is used for receiving and synchronizing the nodes so as to determine the starting time of a time slot for receiving signals;
and the nodes carry out receiving synchronization through the synchronization information sent by each neighbor node, and select the node with the earliest timing as a reference node according to the synchronization result.
Optionally, in this embodiment, the synchronization information may be a preamble signal, which is not limited in this embodiment of the present invention, that is, the synchronization information may also be information that can be synchronized in addition to the preamble signal. In the embodiment, taking the preamble signal as an example, the node in the wireless ad hoc network can transmit the broadcast information including the preamble, so that the node performs receiving synchronization through the preamble transmitted by each neighbor node, and the node with the earliest timing is selected as the reference node according to the synchronization result. For example: as shown in fig. 5, the wireless ad hoc network system is composed of a plurality of nodes, and the nodes communicate with each other through superframes (superframes), frames (frames) and slots (slots). Each superframe consists of 40 frames, each frame consists of 25 time slots, and the time length of each time slot can be 1ms, and the superframe length is 1000 ms. The 0 th time slot of each frame is a broadcast time slot, and is used for sending own broadcast information among nodes in turn, wherein the broadcast information includes a preamble signal (preamble) for receiving synchronization, so that each superframe supports broadcast information sending of 40 nodes at most.
The time slot structure may be as shown in fig. 6, the communication time unit of the wireless ad hoc network node is a time slot, each time slot may have a length of 1ms, and each time slot may include 14 OFDM symbols. Wherein, the first symbol is an Automatic Gain Control (AGC) symbol for performing AGC; the second symbol is a known Preamble signal (Preamble) used for receiving synchronization and frequency offset estimation; the last symbol is GP, two columns of pilot (pilot) symbols are interspersed in the middle for channel estimation and measurement, the blank part is data symbol, and an OFDM modulation mode is adopted, and the structure of each OFDM symbol is as shown in fig. 7, wherein the time slot sampling rate is 30.72MHz, the number of FFT points of OFDM modulation is 2048, the length of cyclic prefix CP of 0 th and 7 th symbols is 160 sampling points, and the length of CP of the rest symbols is 144 sampling points. The maximum delay spread supported by the ad hoc network method and device is as follows:
assuming Transmit-to-receive conversion delay tauRT＝20us，
By
The maximum single-hop coverage distance supported by the GP of 1 OFDM symbol length shown in the figure is:
wherein DmaxDesigning a maximum single-hop coverage distance for the ad hoc network system, wherein the maximum round-trip delay corresponding to the maximum single-hop coverage distance isAnd c is 3 x 10 x 8m/s and is the speed of light.
Therefore, each node receives the broadcast information sent by the neighbor node in the broadcast time slot in each superframe period, performs receiving synchronization through a preamble signal (preamble) of the broadcast information, selects the node with the earliest timing from the synchronization information as a timing reference node of the node according to the synchronization information, and determines the time slot starting time of the node according to the receiving synchronization of the timing reference node.
As shown in the previous figure 2 or 3, when the single-hop coverage range is 7.7km, the system can meet the requirements of no interference and aliasing in transceiving at each node, no interference and aliasing in receiving of different nodes and the requirements of transmission of an ad hoc network.
Another example is: as shown in fig. 8, the ad hoc network system is composed of a plurality of nodes, and the nodes communicate with each other through superframes, frames and time slots. Each superframe is composed of 40 frames, each frame is composed of 25 time slots, the time length of each time slot is 1ms, and the superframe length is 1000 ms. The 0 th time slot of each frame is a broadcast time slot, and is used for sending own broadcast information among nodes in turn, wherein the broadcast information comprises preamble signals used for receiving synchronization, so that each superframe supports the broadcast information sending of 40 nodes at most.
The time slot structure is shown in fig. 9, the communication time unit of the ad hoc network system node is a time slot, the length of each time slot is 1ms, the sampling rate is 30.72MHz, and a plurality of front modulation symbols are AGC symbols for performing automatic gain control; then several symbols are known Preamble signals (Preamble0, used for receiving synchronization and frequency offset estimation, last 2192 blank sampling points are guard intervals GP, blank part is data symbol, symbol has no CP structure, and slot sampling rate is 30.72 MHz.
Let us assume that the maximum delay spread to be supported is τmax4.6875us, Transmit-Transmit conversion time delay tauRT＝20us。
By
The maximum single-hop coverage distance supported by the GP of 2192 sample point lengths shown in the figure is
Wherein DmaxDesigning a maximum single-hop coverage distance for the ad hoc network system, wherein the maximum round-trip delay corresponding to the maximum single-hop coverage distance isAnd c is 3 x 10 x 8m/s and is the speed of light.
Each node receives the broadcast time slot information of the neighbor nodes in each superframe period, performs receiving synchronization through preamble of the broadcast time slot, selects the node with the earliest timing as a timing reference node according to the synchronization information, and determines the time slot starting time of the node according to the receiving synchronization of the timing reference node.
As shown in FIG. 10, assume that node A receives for node BThe node with the earliest timing determined by the time of one superframe is determined as the timing reference node of the node. Let the transmission time of A be T and the propagation delay of the two be tau1B determines the start time of the received time slot n-1 of the node A to be T + tau through the receiving synchronization1If B carries out time slot transmission, the time of time slot transmission is T + tau1,T+τ1+Ts,T+τ1+2Ts,., wherein TsIs the time length of one slot.
As shown in the previous figures 2 and 3, the system can meet the requirements of no interference and aliasing in transceiving at each node and the transmission requirement of an ad hoc network when the single-hop coverage range is 7.0 km.
Optionally, there is only one node at the highest synchronization level in the wireless ad hoc network, or there are multiple nodes at the node at the highest synchronization level in the wireless ad hoc network, where the multiple nodes send synchronization.
The nodes with the highest synchronization level can be nodes which are synchronized by means of GPS or Beidou signals, the nodes are the nodes with the highest synchronization level, and in addition, the nodes can be identified in a broadcast time slot. If the wireless ad hoc network does not have the GPS or the Beidou, the node with the highest synchronization level can be configured in advance, or the node with the earliest timing in the whole network.
Optionally, the method further includes:
and the node receives a signal sent by the receiving node in another time slot, wherein a guard interval exists between the time slot and the adjacent time slot, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
In this embodiment, the GP may also exist between time slots corresponding to signals received by the nodes, so that the GP exists between any two time slots, and overlapping and collision of transceiving between the nodes are avoided.
The ad hoc network system using the method does not need a frame exchange synchronization process under the condition that no GPS or Beidou exists or only partial nodes have the GPS or Beidou, only needs to carry out special design on a frame structure or a time slot structure and meets other limitations, namely, overlapping and conflict of receiving and sending among the nodes can not be caused, and the transmission requirement of the ad hoc network is met. Compared with the existing synchronous ad hoc network system, under the condition that no GPS or Beidou exists or only partial nodes have the GPS or the Beidou, the frame exchange overhead for synchronization can be saved, and the system is particularly considerable under the conditions that the network scale is large and the Ethernet single-hop coverage distance is small.
It should be noted that, in the embodiment of the present invention, various optional implementations described above may be implemented in combination with each other, or may be implemented separately, and the embodiment of the present invention is not limited thereto.
In this embodiment of the present invention, a node sends a signal to a receiving node in a current time slot, where a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and a length of the guard interval is greater than or equal to a sum of a round-trip delay of a wireless ad hoc network and a transceiver conversion delay of a node in the wireless ad hoc network. Therefore, the problems of overlapping and collision of transceiving between nodes can be avoided through the guard interval of the time slot, so that the problems of overlapping and collision of transceiving between nodes do not need to be avoided through frame exchange as in the prior art, and the frame exchange overhead in the wireless ad hoc network is reduced.
Referring to fig. 11, an embodiment of the present invention provides a wireless ad hoc network node, where the wireless ad hoc network node 1100 includes the following modules:
a sending module 1101, configured to send a signal to a receiving node in a current time slot, where a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and a length of the guard interval is greater than or equal to a sum of a round trip delay of the wireless ad hoc network and a transceiver conversion delay of a node in the wireless ad hoc network.
Optionally, the length of the guard interval is greater than or equal to a preset time delay, where the preset time delay is a sum of a round-trip time delay of the wireless ad hoc network, a transceiver switching time delay of a node in the wireless ad hoc network, and a maximum time delay extension in the wireless ad hoc network; or
The current time slot comprises a cyclic prefix, the length of the cyclic prefix is greater than or equal to the maximum delay spread in the wireless ad hoc network, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
Optionally, the node sends, in the current time slot, synchronization information used for the receiving node to perform receiving synchronization so as to determine a time slot starting time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
Optionally, as shown in fig. 12, the node further includes:
a selecting module 1102, configured to select a node with the earliest timing from neighboring nodes as a reference node, and use a time slot starting time of a transmission signal received from the reference node as a starting time of a self-transmission time slot.
Optionally, as shown in fig. 13, the selecting module includes:
a receiving unit 11021, configured to receive broadcast information sent by neighboring nodes, where the broadcast information sent by each neighboring node includes synchronization information, and the synchronization information is used for receiving synchronization by a receiving node to determine a time slot starting time of a received signal;
a selecting unit 11022, configured to perform receiving synchronization through the synchronization information sent by each neighboring node, and select a node with the earliest timing as a reference node according to a synchronization result.
Optionally, there is only one node at the highest synchronization level in the wireless ad hoc network, or there are multiple nodes at the node at the highest synchronization level in the wireless ad hoc network, where the multiple nodes send synchronization.
Optionally, as shown in fig. 14, the node further includes:
a receiving module 1103, configured to receive a signal sent by the receiving node in another time slot, where a guard interval exists between the time slot and an adjacent time slot, and a length of the guard interval is greater than or equal to a sum of a round trip delay of the wireless ad hoc network and a transceiver conversion delay of a node in the wireless ad hoc network.
It should be noted that, in this embodiment, the wireless ad hoc network node 1100 may be a node in the embodiments shown in fig. 1 to 10, and any implementation of the node in the embodiments shown in fig. 1 to 10 may be implemented by the wireless ad hoc network node 1100 in this embodiment to achieve the same beneficial effects, which is not described herein again.
Referring to fig. 15, an embodiment of the present invention provides another wireless ad hoc network node, where the node includes: a processor 1500, a transceiver 1510, a memory 1520, a user interface 1530, and a bus interface, wherein:
the processor 1500, which is used to read the program in the memory 1520, executes the following processes:
and sending a signal to a receiving node in a current time slot through a transceiver 1510, wherein a guard interval exists between the current time slot and a time slot adjacent to the current time slot, and the length of the guard interval is greater than or equal to the sum of a round trip delay of the wireless ad hoc network and a transceiving conversion delay of a node in the wireless ad hoc network.
Among other things, the transceiver 1510 operates to receive and transmit data under the control of the processor 1500.
In fig. 15, the bus architecture may include any number of interconnected buses and bridges, with one or more processors represented by processor 1500 and various circuits of memory represented by memory 1520 being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 1510 may be a number of elements including a transmitter and a receiver that provide a means for communicating with various other apparatus over a transmission medium. The user interface 1530 may also be an interface capable of interfacing with a desired device for different user devices, including but not limited to a keypad, display, speaker, microphone, joystick, etc.
The processor 1500 is responsible for managing the bus architecture and general processing, and the memory 1520 may store data used by the processor 1500 in performing operations.
Optionally, the length of the guard interval is greater than or equal to a preset time delay, where the preset time delay is a sum of a round-trip time delay of the wireless ad hoc network, a transceiver switching time delay of a node in the wireless ad hoc network, and a maximum time delay extension in the wireless ad hoc network; or
The current time slot comprises a cyclic prefix, the length of the cyclic prefix is greater than or equal to the maximum delay spread in the wireless ad hoc network, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
Optionally, the guard interval is located at the beginning or the end of the current time slot, or the guard interval is located in the middle between the current time slot and the adjacent time slot.
Optionally, the node sends, in the current time slot, synchronization information used for the receiving node to perform receiving synchronization so as to determine a time slot starting time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
Optionally, the processor 1500 is further configured to:
and selecting a node with the earliest timing from the neighbor nodes as a reference node, and taking the starting time of the time slot of the transmission signal of the reference node as the starting time of the self-transmission time slot.
Optionally, the selecting a node with the earliest timing from the neighboring nodes as a reference node includes:
receiving broadcast information sent by neighbor nodes through a transceiver 1510, wherein the broadcast information sent by each neighbor node includes synchronization information, and the synchronization information is used for receiving synchronization by a receiving node to determine a time slot starting time of a received signal;
and carrying out receiving synchronization through the synchronization information sent by each neighbor node, and selecting the node with the earliest timing as a reference node according to a synchronization result.
Optionally, there is only one node at the highest synchronization level in the wireless ad hoc network, or there are multiple nodes at the node at the highest synchronization level in the wireless ad hoc network, where the multiple nodes send synchronization.
Optionally, the processor 1500 is further configured to:
the transceiver 1510 receives a signal transmitted by the receiving node in another time slot, where a guard interval exists between the time slot and its adjacent time slot, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceive conversion delay of a node in the wireless ad hoc network.
It should be noted that, in this embodiment, the wireless ad hoc network node may be a node in the embodiments shown in fig. 1 to 10, and any implementation of the node in the embodiments shown in fig. 1 to 10 may be implemented by the wireless ad hoc network node in this embodiment, and the same beneficial effects are achieved, and details are not repeated here.
In the several embodiments provided in the present application, it should be understood that the disclosed method and apparatus may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be physically included alone, or two or more units may be integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device) to execute some steps of the transceiving method according to various embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (14)
1. A wireless ad hoc network communication method, comprising:
a node sends a signal to a receiving node in a current time slot, wherein a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and the length of the guard interval is greater than or equal to the sum of round-trip delay of the wireless ad hoc network and transceiving conversion delay of the node in the wireless ad hoc network;
the method further comprises the following steps:
the node selects a node with the earliest timing from neighbor nodes as a reference node, and takes the time slot starting time of a transmission signal received by the reference node as the starting time of the self transmission time slot, wherein the node with the earliest timing is the node which is received by the node firstly in a signal transmitted in a superframe from the neighbor nodes.
2. The method of claim 1, wherein the length of the guard interval is greater than or equal to a predetermined delay, and the predetermined delay is a sum of a round trip delay of the wireless ad hoc network and a transceive delay of a node in the wireless ad hoc network and a maximum delay spread in the wireless ad hoc network; or
The current time slot comprises a cyclic prefix, the length of the cyclic prefix is greater than or equal to the maximum delay spread in the wireless ad hoc network, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
3. The method of claim 1, wherein the guard interval is located at the beginning or end of the current time slot or is located in the middle of the current time slot and the adjacent time slot.
4. The method of claim 1, wherein said node transmits synchronization information for said receiving node to perform receive synchronization in said current time slot to determine a time slot start time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
5. The method of claim 1, wherein the node selects an earliest timed node among the neighboring nodes as a reference node, comprising:
the node receives broadcast information sent by neighbor nodes, the broadcast information sent by each neighbor node comprises synchronous information, and the synchronous information is used for receiving and synchronizing the nodes so as to determine the starting time of a time slot for receiving signals;
and the nodes carry out receiving synchronization through the synchronization information sent by each neighbor node, and select the node with the earliest timing as a reference node according to the synchronization result.
6. The method of claim 1, wherein there is only one node at a highest synchronization level in the wireless ad hoc network or there are multiple nodes at a highest synchronization level in the wireless ad hoc network, wherein the multiple nodes transmit synchronization.
7. The method of any one of claims 1-4, further comprising:
and the node receives a signal sent by the receiving node in another time slot, wherein a guard interval exists between the time slot and the adjacent time slot, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
8. A wireless ad hoc network node, comprising:
a sending module, configured to send a signal to a receiving node in a current time slot, where a guard interval exists between the current time slot and an adjacent time slot of the current time slot, and a length of the guard interval is greater than or equal to a sum of a round-trip delay of the wireless ad hoc network and a transceiver conversion delay of a node in the wireless ad hoc network;
the node further comprises:
and the selection module is used for selecting the node with the earliest timing from the neighbor nodes as a reference node and taking the time slot starting time of the sending signal of the reference node as the starting time of the sending time slot of the node, wherein the node with the earliest timing is the node which is received by the node in the neighbor nodes in the first time of the sending signal in a superframe.
9. The node of claim 8, wherein the length of the guard interval is greater than or equal to a predetermined delay, the predetermined delay being a sum of a round trip delay of the wireless ad hoc network and a transceive delay of a node in the wireless ad hoc network and a maximum delay spread in the wireless ad hoc network; or
The current time slot comprises a cyclic prefix, the length of the cyclic prefix is greater than or equal to the maximum delay spread in the wireless ad hoc network, and the length of the guard interval is greater than or equal to the sum of the round trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
10. The node of claim 8, wherein the guard interval is located at the beginning or end of the current time slot or is located in the middle of the current time slot and the adjacent time slot.
11. The node of claim 8, wherein the node transmits synchronization information for the receiving node to perform receive synchronization in the current time slot to determine a time slot start time of a received signal; or
And the node sends synchronization information used for receiving synchronization by the receiving node in the frame to which the current time slot belongs so as to determine the starting time of the time slot of the received signal.
12. The node of claim 8, wherein the selection module comprises:
the receiving unit is used for receiving broadcast information sent by neighbor nodes, the broadcast information sent by each neighbor node comprises synchronous information, and the synchronous information is used for receiving and synchronizing the receiving nodes so as to determine the starting time of a time slot of a received signal;
and the selection unit is used for carrying out receiving synchronization through the synchronization information sent by each neighbor node and selecting the node with the earliest timing as a reference node according to a synchronization result.
13. The node of claim 8, wherein there is only one node at a highest synchronization level in the wireless ad hoc network or there are multiple nodes at a highest synchronization level in the wireless ad hoc network, wherein the multiple nodes transmit synchronization.
14. The node according to any of claims 8-11, characterized in that the node further comprises:
and the receiving module is used for receiving a signal sent by the receiving node in another time slot, wherein a guard interval exists between the time slot and the adjacent time slot, and the length of the guard interval is greater than or equal to the sum of the round-trip delay of the wireless ad hoc network and the transceiving conversion delay of the node in the wireless ad hoc network.
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Address after: 100191 No. 40, Haidian District, Beijing, Xueyuan Road Patentee after: CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY Address before: 100191 No. 40, Haidian District, Beijing, Xueyuan Road Patentee before: CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY |
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Effective date of registration: 20210601 Address after: 100085 1st floor, building 1, yard 5, Shangdi East Road, Haidian District, Beijing Patentee after: DATANG MOBILE COMMUNICATIONS EQUIPMENT Co.,Ltd. Address before: 100191 No. 40, Haidian District, Beijing, Xueyuan Road Patentee before: CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY |