JP2006157501A - Multiplexing method of upper and lower bidirectional packets in wireless multi-hop network with periodic intermittent transmission - Google Patents

Abstract

An object of the present invention is to improve transmission efficiency at the time of uplink / downlink packet multiplex transmission in wireless multi-hop relay transmission.
In the present invention, two or more core nodes are combined and realized. In FIG. 2, the core nodes CN_D and CN_U correspond to them. In this embodiment, packets are always relayed in one direction regardless of the up / down line direction. For example, when a downlink packet is relayed and transmitted to the node IN_1, a downlink packet addressed to the node IN_1 from the core node CN_D is multi-hop relayed via a relay node installed between the core node CN_D and the node IN_1. On the other hand, when an uplink packet is transmitted from the node IN_1, the multi-hop relay is performed from the node toward the core node CN_U via a node located between both nodes.
As described above, according to the second embodiment of the present invention, it is possible to eliminate the collision between the uplink packet and the downlink packet, which is a problem in the conventional up / down bidirectional packet multiplexing described in FIG. .
[Selection] Figure 2

Description

The present invention relates to a multiplexing method for upper and lower bidirectional packets in a wireless multi-hop network in which wireless nodes exist and each wireless node relays packets with each other wirelessly. In particular, the present invention relates to a periodic intermittent transmission method as a packet relay transmission method. The present invention relates to a multiplexing method for upper and lower bidirectional packets in the case where is applied.

  In a next-generation mobile communication system that accommodates a broadband of several tens of Mbps, it is essential to narrow the cell radius. However, when a cell is narrowed, an extremely large number of base stations must be installed in order to make a wide area as a service area. The biggest problem is that a huge investment is required to construct a wired line for connecting each base station to the backbone network. Therefore, a base station (core node) connected to a wired network is installed in various places, and a cellular network (hereinafter, wireless base station relay) that covers an area that cannot be covered by this core node group by a relay node connected by wireless multi-hop relay. Network) is under consideration. When this wireless base station relay network is used, it is possible to suppress investment because only a core node is required for laying a wired line. The problem here is how to realize packet relay transmission with high transmission efficiency in a wireless multi-hop network.

As a packet relay transmission method for realizing packet relay transmission with high transmission efficiency, Reference Document 1 proposes an intermittent periodic transmission method. Hereinafter, the packet transmission method will be described.
FIG. 5 is a sequence diagram for explaining the periodic intermittent transmission method shown in Reference 1. In FIG. 5, it is assumed that the nodes are arranged at regular intervals. In the example of FIG. 5, the frequency reuse distance is 3. That is, for example, it means that the same frequency can be used repeatedly at the start node N_S and the relay node N_4.
The periodic intermittent transmission method is characterized in that a packet is transmitted at a constant transmission period P_S_3 at the start node N_S, while the relay node N_i is relayed to the relay destination node immediately after receiving the packet. By giving the transmission cycle P_S_3 as shown in FIG. 5, for example, the nodes that reuse the same frequency at time T1 are N_S and N_4, and it can be seen that the frequency reuse distance 3 is satisfied.
FIG. 6 shows a sequence diagram for explaining relay transmission by the periodic intermittent transmission method shown in Reference 1 in the case of the frequency reuse distance 5. The difference from FIG. 3 is that the transmission cycle at the start node N_S is set to P_S_5 due to the increased reuse distance. P_S_5 is set longer than P_S_3. It can be seen that the nodes using the same frequency at time T1 are N_S and N_5, and the same frequency reuse distance 5 is obtained.
As described above, in the periodic intermittent transmission method, it is possible to control the frequency reuse interval by transmitting packets periodically and intermittently at the start node, while relaying the packets immediately at the relay node. By giving a transmission cycle as a reuse interval, it is possible to achieve maximum throughput.
As is clear from FIGS. 4 and 5, according to the periodic intermittent transmission method, the throughput observed at the end node N_E can be kept constant regardless of the number of relay stages.

(Reference 1) H. Furukawa, “Hop Count Independent Throughput Realization by A New Wireless Multihop Relay,” in Proc. IEEE VTC 2004 Fall, 4.4.2.2, Sep. 2004.

Consider packet multiplexing in both uplink and downlink in a wireless multi-hop network to which the periodic intermittent transmission method is applied. FIG. 7 is a diagram showing a case where packets in the uplink and downlink directions are multiplexed by a conventional technique in a wireless multi-hop network to which the periodic intermittent transmission method is applied. A state is shown in which a plurality of relay nodes are arranged on a straight line between the core node CN and the terminal node EN. The core node CN is connected to the wired backbone network and plays a role of packet bridging (gateway) with the wired backbone network. The arrows in FIG. 7 indicate the packet relay direction. The uplink indicates the direction UL from the termination node EN to the core node CN, and the downlink indicates the opposite direction DL. Downlink packets are periodically transmitted intermittently by the core node CN, and uplink packets are periodically transmitted intermittently by the termination node EN.
However, when the uplink / downlink packets are multiplexed by the conventional uplink / downlink packet multiplexing method shown in FIG. 7, collision of the uplink / downlink packets occurs in the radio channel in the middle of relay, and regular frequency reuse and termination by periodic intermittent transmission is performed. There arises a problem that high-efficiency packet relay with constant throughput at the node cannot be realized.
If different frequencies are used for the packet relay radio lines for the upper and lower lines, there will be no collision between the upper and lower line packets on the radio line in the middle of the relay, resulting in transmission efficiency. There is a case where packets are transmitted and received at the same time, and two relay radios for one node are required, which complicates the apparatus.

In the present invention, when the periodic intermittent transmission method is selected as the packet mid-range transmission method, there is a problem that it becomes impossible to achieve regular frequency reuse destruction and constant throughput, which has been a problem when conventional uplink / downlink packet multiplexing is applied. The present invention relates to a method for solving this problem and producing the effect of the periodic intermittent transmission method even when uplink and downlink packets are multiplexed.

In order to solve the above problems, the present invention shows three methods. First, a method of performing uplink / downlink packet relay transmission in a time-divided manner is shown. Second, it shows a method of installing two or more core nodes (a node that bridges the wired backbone network and the relay network) and always relaying and transmitting packets in one direction regardless of the type of the upper and lower lines. . Thirdly, a method is described in which a relay path is formed in a ring shape, and packets are always relayed and transmitted in one direction regardless of the type of the up / down line.

According to the first method of the present invention, it is possible to avoid collision between bidirectional packets due to relaying of uplink and downlink packets by performing uplink and downlink packet relay transmission divided in time, and the periodic intermittent transmission method An effect can be produced. Further, according to the first method of the present invention, when different frequencies are used for the packet relay radio channels of the upper and lower lines, the possibility of simultaneously transmitting and receiving packets in the upper and lower lines in one node can be avoided. It is only necessary to install one relay radio.
According to the second method of the present invention, it is possible to avoid collision between bidirectional packets due to relaying of uplink / downlink packets by always relaying packets in one direction, and the effect of the periodic intermittent transmission method can be achieved. Can be generated. In addition, according to the second method of the present invention, it is sufficient to perform one-way relaying by means of up / down lines, and it is possible to avoid the possibility of sending and receiving packets simultaneously at the up / down lines in one node. Only one unit needs to be installed.
According to the third method of the present invention, as in the second method, it is possible to avoid collision between bidirectional packets due to relaying of uplink and downlink packets by always relaying and transmitting packets in one direction. It is possible to produce the effect of the intermittent transmission method.

FIG. 1 is a diagram showing a first embodiment of upper and lower bidirectional packet multiplexing according to the present invention. The first embodiment is characterized in that uplink packet transmission and downlink packet transmission are switched at different times so as not to be mixed with each other. That is, as shown in FIG. 1 (a), the end node EN periodically transmits an upstream packet intermittently at a certain time, and at a certain time, the downstream packet is transmitted at a certain time as shown in FIG. 1 (b). This is performed by the core node CN periodically transmitting intermittently.
As described above, according to the first embodiment of the present invention, the uplink packet and the downlink packet, which are problematic in FIG. 7, do not collide at a certain moment. Therefore, regular frequency reuse is performed by periodic intermittent transmission. Thus, it is possible to realize a highly efficient packet relay in which the throughput is constant at the terminal node.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment according to the present invention is realized by combining two or more core nodes. In FIG. 2, the core nodes CN_D and CN_U correspond to them. In this embodiment, packets are always relayed in one direction regardless of the up / down line direction. For example, when a downlink packet is relayed and transmitted to the node IN_1, a downlink packet addressed to the node IN_1 from the core node CN_D is multi-hop relayed via a relay node installed between the core node CN_D and the node IN_1. On the other hand, when an uplink packet is transmitted from the node IN_1, the multi-hop relay is performed from the node toward the core node CN_U via a node located between both nodes.
As described above, according to the second embodiment of the present invention, the uplink packet and the downlink packet, which are problematic in the conventional up / down bidirectional packet multiplexing described with reference to FIG. By intermittent transmission, it is possible to realize regular frequency reuse and high-efficiency packet relay with constant throughput at the end node.
FIG. 3 is a diagram showing another example of the second embodiment of upper and lower bidirectional packet multiplexing according to the present invention. In the present embodiment, one more core node CN_I is installed between the core node CN_D and the core node CN_U. The core node CN_I receives an upstream packet generated in any node of the node group IN_L and bridges the packet to the wired backbone network, while a downstream packet addressed to any node in the node group IN_R that arrives from the wired backbone network. Multi-hop relaying in the right direction in FIG.
According to the present embodiment, since the uplink packet generated in the node group IN_L is bridged to the core wired network by the core node CN_I, a margin can be generated in the relay transmission in the node IN_R group. In addition, for relay transmission in the node IN_L group, it is not necessary for the core node CN_D to transmit a downstream packet to the node IN_R group, so that a margin can be generated.

FIG. 4 shows a third embodiment of the upper and lower bidirectional packet multiplexing method in the present invention. Both the upper and lower line packets are relayed and transmitted in one way in the counterclockwise direction in FIG. Downstream packets destined for each node are transmitted from the core node CN_A, and upstream packets transmitted from each node are relayed to the core node CN_A relayed clockwise.
According to the present embodiment, there is no need to install two core nodes. However, for example, it is possible to newly install a core node at the location of the node IN_1 in FIG. In this case, the relay operation is performed in the same manner as that in FIG. 3, and it is possible to reduce the load applied to each intermediate plan line, and as a result, it is possible to improve the capacity of the intermediate plan line.

By combining the periodic intermittent transmission method and the uplink / downlink multiplexing method according to the present invention, it is possible to construct a high-efficiency and large-capacity wireless relay line in both the up and down directions.

First embodiment of upper and lower bidirectional packet multiplexing according to the present invention Second embodiment of upper and lower bidirectional packet multiplexing according to the present invention Another example of the second embodiment of upper and lower bidirectional packet multiplexing according to the present invention Third embodiment of upper and lower bidirectional packet multiplexing according to the present invention The first figure explaining the periodic intermittent transmission method The second figure explaining the periodic intermittent transmission method Traditional Up / Down Bidirectional Packet Multiplexing in Wireless Multihop Networks with Periodic Intermittent Transmission

Explanation of symbols

EN Terminal node CN Core node that bridges the packet between the wired backbone network and the relay network CN_D Downlink packet transmission specialized core node CN_U Uplink packet reception specialized core node IN_1 node CN_I Core nodes IN_L, IN_R arranged in the relay path Node group CN_A Core node i (i = 1, 2,..., N) Relay node number N_i Relay node of relay node i N_S Start node N_E End node f1, f2... F1, F2 .. Frequency P_S Transmission at start node Period P_i Transmission waiting time in relay node i P_S_3, P_S_5 Transmission period in case of frequency reuse distance 3, 5 DL Downlink relay UL Uplink relay T1 Time

Claims (7)

In wireless multi-hop relay where a plurality of nodes are interconnected to form an unbranched relay route,
An uplink / downlink packet multiplexing method characterized in that uplink packet relay and downlink packet relay are performed separately for each time. In wireless multi-hop relay where a plurality of nodes are interconnected to form an unbranched relay route,
An uplink / downlink packet multiplexing method characterized in that packets are always relayed and transmitted in one direction regardless of the type of uplink or downlink. The node located at the end of the relay path periodically transmits a packet intermittently, and a node other than the node relays the packet to an upper node immediately after receiving an incoming relay packet. The uplink / downlink packet multiplexing method according to claim 1 or claim 2. In wireless multi-hop relay where a plurality of nodes are interconnected to form an unbranched relay route,
An uplink / downlink packet multiplexing method characterized in that nodes at both ends of the relay path are interconnected to form an annular relay path, and packets are always relayed and transmitted in one direction regardless of the type of uplink or downlink. A node located in the middle of the relay path intermittently transmits a packet periodically, and a node other than the node relays the packet to an upper node immediately after receiving an incoming relay packet. Item 5. The uplink and downlink packet multiplexing method according to Item 4. 6. The up-and-down line according to claim 3 and 5, wherein the node that intermittently transmits packets periodically connects to a wired backbone network, and delivers the packet between the wired backbone network and the relay network. Packet multiplexing. The uplink / downlink packet multiplexing method according to claim 1, wherein a node connected to a plurality of wired backbone networks exists in the middle of the relay route.

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