GB2548797A - Wireless communications networks - Google Patents

Abstract

A wireless mesh communications network comprises network node devices 20, 22, 24, 26, 28, 30 each having a transceiver unit and wireless communications links 21, 23, 25, 27, 29, 31, 35 interconnecting the transceiver units arranged in an existing physical topology. A sub-network 33, 34 of the network node devices interconnected by chosen wireless communications links is determined, the sub-network 33, 34 being defined as part of the existing physical topology of the wireless mesh communications network and being determined in dependence upon a predetermined metric for the existing physical topology of the wireless mesh communications network. One of the network node devices 20, 26 of the sub-network 33, 34 is designated as a control unit for the sub-network 33, 34 and the sub-network information defining the sub-network and control unit is provided to a routing agent. Upon receiving the sub-network information, the routing agent defines a routing table for the wireless mesh communications network using the sub-network information.

Description

WIRELESS COMMUNICATIONS NETWORKS

The present invention relates to wireless communications networks, and in particular to wireless mesh communications networks.

BACKGROUND OF THE INVENTION

Figure 1 of the accompanying drawings illustrates a simplified example wireless mesh communications network which comprises a plurality of network node devices 10 interconnected by bidirectional wireless communications links 12. The network node devices 10 operate to communicate with one another, for the transfer of communications data therebetween. This type of network is known as a “mesh” network because of the multiple connections between network node devices that defines a mesh of communications links 12.

Wireless mesh networks are strong candidates to provide data communications, for example for Internet access, or for backhaul data traffic from small cell base stations. This is primarily because such wireless mesh networks require no cabling and can be deployed and extended in a flexible manner. Transmission and routing of data packets in a wireless mesh network is affected by many factors, including wireless link quality. This is particularly the case with outdoor networks in which the link quality can be affected by many different outdoor factors such as weather or other signal attenuating and blocking factors. In addition, low latency and low packet drop are highly desirable in such networks, since consumers desire high quality, high speed services, particularly for the delivery of online content over the wireless network. Early wireless mesh networks employed Wi-Fi technology with omnidirectional antenna, but are no longer able to meet the data throughput rates (measured across the mesh from one edge node to another) of today's data traffic requirements. In addition, such techniques are subject to interference as the unlicensed 5GHz band becomes more congested. This has led to interest in high speed millimetre wave wireless networks, such as those operating in the 60GHz waveband, for example as defined in the Institute of Electrical and Electronic Engineers (IEEE) Standard IEEE 802.11 ad. Such networks offer much higher capacity than the Wi-Fi mesh networks by exploiting large carrier bandwidth and (steerable) directional antenna to give high signal to noise ratios.

In wireless networks, such as those implemented according to the IEEE 802.11 ad standard mentioned above, sub-networks are often defined in combination with the routing and packet forwarding definitions, with traffic being forwarded across the mesh via multiple sub-networks. In IEEE 802.11 ad a sub-network is called a Personal Basic Service Set (PBSS), and comprises two or more radio nodes (or stations, STA) sharing access to a radio carrier over a local area. There are a multitude of ways in which radio nodes can be assigned to PBSSs and also a multitude of ways in which traffic can be routed over the mesh network which is thereby created. Clearly, identification of the combination of mesh network design and routing tables that gives the greatest performance (for example, measured using key performance indicators (KPI) such as mean latency or throughput) is non-trivial. A joint design of the mesh network design and the routing algorithms implies a centralised algorithm which precludes the use of decentralised components.

Accordingly, it is desirable to provide a technique that can address the complexity of mesh network design and routing methods, suitable for use in such high speed wireless communications networks.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a method of managing data transfer in a wireless mesh communications network which comprises a first plurality of network node devices each having a transceiver unit, a second plurality of wireless communications links which interconnect the transceiver units of the network node devices, a network definition agent, and a routing agent, the network node devices being arranged in an existing physical topology, the method comprising at the network definition agent of the wireless mesh communications network determining a sub-network within the wireless mesh communication network, the sub-network having a third plurality of transceiver units chosen from the transceiver units of the first plurality of network node devices, the third plurality of transceiver units being interconnected by a fourth plurality of wireless communications links chosen from the second plurality of communications links, the sub-network being defined as at least a part of the existing physical topology of the wireless mesh communications network, and being determined in dependence upon at least one predetermined metric for the existing physical topology of the wireless mesh communications network; designating one of the network node devices of the third plurality of network node devices as a control unit for the sub-network; providing sub-network information defining the sub-network and control unit to the routing agent of the wireless mesh communications network; and, at the routing agent of the wireless mesh communications network, receiving subnetwork information from the network definition agent; defining a routing table for the wireless mesh communications network using the sub-network information. A wireless mesh communications network comprising a first plurality of network node devices each having a transceiver unit, interconnected by a second plurality of wireless communications links which interconnect the transceiver units of the network node devices in an existing physical topology, a network definition agent, and a routing agent, wherein the network definition agent comprises a determination unit operable to determine a sub-network within the wireless mesh communication network in dependence upon at least one predetermined metric for the existing physical topology of the wireless mesh communications network, the sub-network having a third plurality of transceiver units of network node devices chosen from transceiver units of the first plurality of network devices, the third plurality of transceiver units being interconnected by a fourth plurality of wireless communications links chosen from the second plurality of communications links, the sub-network being defined as at least a part of the existing physical topology of the wireless mesh communications network; a designation unit operable to designate one of the network node devices of the third plurality of network node devices as a control unit for the sub-network; and an output unit operable to provide sub-network information defining the sub-network and control unit to the routing agent, and wherein the routing agent comprises an input unit operable to receive sub-network information from the network definition agent; and a routing unit operable to define a routing table for the wireless mesh communications network using the sub-network information.

The network may further comprise a plurality of switches, and a routing table is provided for each such switch.

The network definition agent may be provided by a discrete dedicated unit, or may be distributed across multiple elements of the network, or may be distributed across multiple elements inside and/or outside the network.

The routing agent may be provided by a discrete dedicated unit, or may be distributed across multiple elements of the network.

In one example, the control node comprises a plurality of transceiver units having respective directions of operation, the network definition agent being operable to determine which of the transceiver units provide wireless communications links for the control node; and the designation unit being operable to designate one of the transceiver units of the control node as a sub-network controller.

In one example, at least one of the third plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

In one example, each of the third plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

In one example, each of the first plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

In one example, the respective directions of operation are substantially mutually perpendicular.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic block diagram illustrating a wireless mesh communications network;

Figure 2 is a schematic block diagram illustrating sub-networks in a first wireless mesh communications network;

Figure 3 illustrates a multi antenna network node device;

Figure 4 is a schematic block diagram illustrating sub-networks in a second wireless mesh network;

Figure 5 illustrates constraints on sub-network definition;

Figure 6 is a schematic block diagram illustrating a sub-network definition controller;

Figure 7 is a flow chart illustrating steps ion a method embodying an aspect of the present invention;

Figure 8 illustrates an example PBSS designer; and

Figure 9 illustrates interaction of the PBSS designer of Figure 8 with a routing calculation agent and network nodes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 illustrates an “ideal” grid-like mesh communications network is which the network node devices 10 are arranged in a regular, predictable grid. As such, organisation of the network node devices 10 into appropriate sub-networks (also known as Personal Basic Service Sets - PBSSs - in the IEEE 802.11 ad standard) is relatively straightforward. The grid structure allows simple rules to be applied for the sub-division without consideration of the traffic routing/forwarding algorithm of the mesh, and enables the sub-network definition and routing calculations to be taken in sequence in a single calculation entity or separate entities.

However, for “off-grid” networks in which the network node devices are arranged in a random or at least in an irregular manner, definition of sub-networks is more difficult since, for example, any single network node device could belong to any one of a number of potential sub-networks. A simplified off-grid network is illustrated in Figure 2. A first network node device 20 is connected with a wider network 19 via an external connection 20E. The external connection 20E may be provided by a high speed wireless connection or by a wired connection such as an optical fibre connection.

The first network node device 20 is able to communicate with second and third network node devices 22 and 24 over respective wireless communication links 21 and 23. The second and third network node devices 22 and 24 are able to communicate with one another over a wireless communications link 25.

The wireless communications links are preferably millimetre wave communications links, for example in the 60GHz waveband governed by the IEEE 802.11 ad standard. It will be readily appreciated, however, that the techniques discussed herein are applicable to any wireless communications link technology. A fourth network node device 26 is connected with the wider network 19 via an external connection 26E, similar to that of the first network node device 20. The fourth network node device 26 is able to communicate with fifth and sixth network node devices 28 and 30 via wireless communications links 27 and 31, and the fifth and sixth network node devices 28 and 30 communicate with one another via a wireless communications link 29.

The network of Figure 2 is able to be sub-divided into two sub-networks 33 and 34. The first of the sub-networks 33 comprises the first, second and third network node devices 20, 22 and 24, and the second of the sub-networks 34 comprises the fourth, fifth and sixth network node devices 26, 28 and 30. The first network node device 20 is defined as the control node for the first sub-network 33, and the fourth network node device 26 is defined as the control node for the second sub-network 34.

The control node for each sub-network 33 and 34 controls the channel on which the sub-network concerned operates and controls communications within the subnetwork concerned. When the first and second subnetworks are connected only by the wider network 19, routing of data packets from one of the network node devices in the first subnetwork to a network node device in the second subnetwork brackets (or vice versa) is realised through the wider network 19, using the external links 20E and 26E.

In one possible example, the third network node device 24 and fifth network node device 28 are also able to communicate over a wireless communication link 35. In such a case, routing may take place over that communications link 35 or via the wider network 19. Such routing decisions are made independently of the definition of the first and second sub-networks 33 and 34.

Figure 3 illustrates schematically a multi-antenna, multi-direction network node device. The network node device 40 of Figure 3 has four transmitting and receiving antenna units 40A, 40B, 40C and 40D, and an external network connection 40E. Each antenna unit is operable to receive and transmit data packets over a beam forming directional antenna. Each antenna has a nominal central direction 41 A, 41B, 41C or 41D, and is able to communicate over a range of directions indicated in Figure 3 by 42A, 42B, 42C and 42D. In transmission mode, each antenna unit is operable to receive data packets for transmission, to modulate those data packets to generate modulated signals, and to transmit the modulated signals from the antenna device in a direction determined by the wireless communications link. In reception mode, the antenna unit is operable to receive detected modulated signals from the antenna device, to demodulate such received signals, and to supply demodulated data packets for further processing and routing. A switching unit 40S is provided and is operable to switch data packets from one antenna unit 41 A, 41B, 41C or 41D to another of the units for further transmission from the network node device concerned. The switching unit 40S operates in accordance with routing control instructions, and will not be described here in detail for the sake of conciseness.

Figure 4 illustrates a more complex off grid network in which the network node devices are multi-antenna, multi-direction node devices, such as described with reference to Figure 3. As such, each network node device has a plurality of communication directions. In Figure 4, each network node device is provided with four possible connection directions, provided by respective transceiver units. Each transceiver unit includes a media access control (MAC) layer, a physical (PHY) layer and an antenna device. In effect, each network node device provides four bidirectional network node devices, connected together by an internal switching arrangement. Any number of network node devices may be provided with any number of transceiver units, as appropriate for the network concerned. For example, each network node device may be provided with two, three or four transceiver units, and include switch means to connect data packets between the transceiver units of the node.

The transceiver units of the network node devices of the example shown in Figure 4 serve respective directions which are substantially mutually perpendicular. It will be appreciated that the respective antennas of the transceiver units may be arranged to serve any set of chosen directions.

In Figure 4, a first network node device 52 is connected to an external network via an external connection 52E. The external connection 52 E may be a wireless connection or may be a wired connection such as an optical connection. The first network node device 52 has four antennas and associated transmission and reception units 52A, 52B, 52C and 52D, hereafter referred to as transceiver units 52A, 52B, 52C and 52D. The transceiver units 52A, 52B, 52C and 52D are operable to transmit and receive radio frequency signals in respective directions, using millimetre wavelength signals, for example in the 60GHz waveband according to the IEEE 802.11 ad standard. Each transceiver unit 52A, 52B, 52C and 52D includes a beamforming directional antenna element which is operable to steer the direction of transmission or reception within a predetermined range centred on the centre direction of the antenna element. This beamforming and directionality of the antenna enables each transceiver unit 52A, 52B, 52C and 52D of the first network node device 52 to communicate with different network node devices at different network in different spatial positions.

The first network node device 52 also includes a switching unit 52S (not shown for clarity, see Figure 3) which is operable to switch data packets between transceiver units 52A, 52B, 52C and 52D of the first network node device. The switching unit 52S enables data packets received by one transceiver unit to be transmitted from the first network node device 52 from a different transceiver unit. As such, data packets can be routed appropriately through the first network node device 52.

Having multiple transceiver units connected by the switching unit enables the network node device to provide a plurality of node devices in a single unit. The arrangement of the respective directions of the antenna elements of the transceiver units combined with the beamforming directionality of the antenna elements enables the network node device to communicate with multiple different network node devices and enables the definition of a mesh network.

The example network of Figure 4 will now be used to describe the process of defining sub-networks within the overall network. Firstly, the possible connections will be set out, and then the definition of sub-networks described. It will be readily understood that the network topology of Figure 4 is merely exemplary, and is not reproduced to scale. The connections described are intended to represent the connections available for the exemplary network. Accordingly, the Figure 4 network, and the following description, is not to be considered limiting.

In the example of Figure 4, a total of six network node devices 52, 54, 56, 60, 62 and 64 are illustrated. Each of the network node devices 52, 54, 56, 60, 62 and 64 includes a multiple number of transceiver units A, B, C and D and a switching unit S, as described above with reference to Figure 3 and to the first network node device 52. The provision of multiple transceiver units in multiple network node devices allows for many potential wireless connections to be made.

In the example of Figure 4, transceiver unit 52C of the first network node device 52 is able to communicate with transceiver unit 53A of the second network node device 54, with transceiver unit 56A of the third network node device 56, and with transceiver unit 60D of the fourth network node device 60 over respective wireless communications links 51, 53 and 59.

Transceiver unit 54A of the second network node device 54 is able to communicate with transceiver unit 52C of the first network node device 52, with transceiver unit 56C of the third network node device 56, and with transceiver unit 62D of the fifth network node device 62 over respective wireless communications links 51, 55, and 57.

Transceiver unit 56A of the third network node device 56 is able to communicate with transceiver unit 52C of the first network node device 52 over wireless communications link 53. Transceiver unit 56C of the third network node device 56 is able to communicate with transceiver unit 54A of the second network node device 54 over wireless communications link 55.

Transceiver unit 60D of the fourth network node device 60 is able to communicate with transceiver unit 52C of the first network node device 52, and with transceiver unit 62B of the fifth network node device 62 over respective wireless communications links 59 and 61. The fourth network node device 60 also is connected with an external network via an external connections 60E, in a manner similar to that described for the first network node device 52.

Transceiver unit 62B of the fifth network node device 62 is able to communicate with transceiver unit 60D of the fourth network node device 60, and with transceiver unit 64D of the sixth network node device 64 over respective wireless communications links 61 and 63. Transceiver unit 62D of the fifth network node device 62 is able to communicate with transceiver unit 54A of the second network node device 54 over wireless communications link 57.

Transceiver unit 64D of the sixth network node device 64 is able to communicate with transceiver unit 62B of the fifth network node device 62 over wireless communications link 63.

It will be appreciated that the exact nature of the available communications links in the network is not important to principles of the invention, and that the network shown in Figure 4 is shown merely by way of example in order to explain those principles. In the example of Figure 4, it is assumed that the wireless communications links described are the only wireless links available for the purposes of describing the principles of the present invention. The wireless mesh network shown in Figure 4 is defined by the existing physical topology of the network node devices. That is, the wireless communications links that are available are determined by the physical layout of the network node devices and the environment in which they are placed. For example, a specific location of a network node device may preclude communication in one or more directions for that device, due to local physical conditions.

An example of a restriction on the definition of a sub-network is illustrated in Figure 5. In Figure 5, a first network node 80 is in communication with a second network node 82 over a communications link 81 defined between respective transceiver units 80B and 82D. The transceiver unit 80B and 82D of the first and second network nodes 80 and 82 respectively are initially defined as a sub-network, with either of the nodes performing the role of the sub-network controller. A transceiver unit 84D of a third network node 84 joins the sub-network, and communicates with the first network node 80 over the communications link 83. The communications link 83 is defined between the transceiver unit 80B of the first network node and the transceiver unit 84D of the third network node 84.

The transceiver unit 84D of the third network node 84 is not able to communicate directly with the transceiver unit 82D of the second network node 82. Accordingly, the second and third sub-network nodes 82D and 84D cannot be defined as the subnetwork controller for the sub-network shown in Figure 5. Therefore, the first subnetwork node 80B must be defined as the sub-network controller, since it the only controller that is able to communicate directly with all of the members of the subnetwork. Thus, the location of the third network node imposes a constraint on the definition of the sub-network with which the third network node is joining.

It will be readily appreciated that the sub-network shown in Figure 5 is very simplified, and is shown merely to illustrate a typical constraint on the definition of the sub-network.

Returning to the example network of Figure 4, there are several sub-networks that can be defined. A first sub-network 70 can be defined as including the first, second, third and fourth network node devices 52, 54, 56 and 60, using respective transceiver units 52C, 54A, 56A and 60D. For the first sub-network 70, transceiver unit 52C is defined as the control unit since transceiver unit 52C is the only one of the units able to communicate directly with each of the other members of the subnetwork. A second sub-network 72 can be defined as including the second, third and fifth network node devices 54, 56 and 62, using transceiver units 54A, 56C and 62D.

Any of the network node devices belonging to the second sub-network can be designated as the sub-network controller, since all of the devices are in direct communication with all of the other devices in the sub-network. However, transceiver unit 54A should not be placed in both the first and second subnetworks (otherwise very tight coordination is required between PCPs to allow the coexistence), and so this conflict must be resolved during the subnetwork definition process. A third sub-network 74 can be defined as including the fourth, fifth and sixth network node devices 60, 62 and 64, using respective transceiver units 60D, 62B, and 64D.

It will be appreciated that the network layout shown in Figure 4 is merely exemplary, and is intended to illustrate the principles of the present invention, which may be applied to any suitable wireless mesh network.

In order to define the relevant sub-networks, sub-network definition functionality is provided in the network. This definition functionality may be provided by the switch units in any one or more of the network node devices, in a centralised controller 76, which may a software-defined network (SDN) controller, or distributed amongst an appropriate number of the units.

Figure 6 illustrates a controller 90 for providing the sub-network definition functionality. The controller 90 comprises a control unit 92, an input unit 94, a data storage unit 96, and output unit 98, and a user interface 100. Any or all of these units may be provided by dedicated hardware units, or may be provided by shared resources in an existing controller or processing unit of the network.

The input unit 92 is operable to provide data input for the control unit 92, as will be described below. The control unit 92 is operable to perform the required subnetwork definition operations, to store in, and retrieve data from, the data storage unit 96, and to output data via the output unit 98. The user interface 100 is operable to provide user interface functions for the controller 90. The data storage unit 96 stores data relating to network topology, data traffic expectations, path loss modelling for the wireless communications links, and rules relating to the principles of the sub-network definition. The control unit 92 is operable to access and update this data in the data storage unit 96. Control unit 92 is also known as a PBSS Designer, so called because it specifies the composition of each PBSS in the mesh network (which 802.11 ad STAs belong to each PBSS and which STA acts as the controller (PCP)), and also the radio channel of each PBSS (since multiple radio channels are available in the 60 GHz band and radio channels can also be divided into sub-channels -exploiting radio channels reduces the impact of interference between PBSSs).

Definition of sub-networks in a wireless mesh network will now be described with reference to Figure 6 and the flow chart of Figure 7.

At step 101, the control unit 92 retrieves network topology data from the data storage unit 96. This network topology data may include information relating to physical locations of the network nodes in the network, the number of transceiver units per network node device, and the ranges of possible communications directions for those transceiver units.

At step 102, the input unit 94 provides real-time data relating to the network to the control unit 92. This real-time data may include measurements from one or more of the network node devices. For example, the real-time data may include information showing which other network node devices have been detected by a given network node, signal strengths for wireless communications links between network node devices, and/or other relevant information.

At step 103, the control unit 92 retrieves data relating to the rules and principles by which the sub-networks are to be defined. For example, the rules information may include at least one performance metric for the network, such as maximum latency for data packets traversing the network. Other examples of performance metrics for the network include reliability of data packet transmission, minimum data packet throughput rate, and network robustness.

At step 104, the control unit 92 combines the retrieved topology data, the received real-time data and the retrieved rules data in order to define at least one sub-network for the network. For each such sub-network, a sub-network controller is chosen from the network node devices forming the sub-network concerned.

At step 105, the sub-network definitions data are stored in the data storage unit 96. The sub-network definitions data are then accessible by routing functionality which determines routes through the network for specific data packet flows.

Steps 101 to 105 may be repeated at appropriate times, for example periodically.

In such a manner, sub-networks are able to be defined with lower impact on network performance than in previously-considered techniques.

Figure 8 illustrates an example PBSS designer 110. The designer 110 includes a design unit 112, which runs multiple design algorithms/heuristics 112A, 112B, 112C. The design algorithms/heuristics 112A, 112B, 112C receive an input 114, which may include some or all of the following data: • topographical information (for example, node locations, possible antenna azimuths, STAs per Node) • radio environment information (for example, this could be model based and comprise a path loss model to apply (line-of-sight, non-line-of-sight, path loss exponent), shadowing model, expected rainfall rate, small-scale fading model, or it could include radio measurements from field testing (including from the live network if the designer is executed on a network that is up and running) or estimated by an external tool (e.g. a radio planning tool) • objectives of design (e.g. robustness to failover or link performance degradation (e.g. from rain or foliage growth or other partial shadowing), max aggregate throughput, minimum latency, minimum mean latency).

The design algorithms/heuristics 112A, 112B, 112C use the input data to generate respective PBSS designs. The designs capture which network nodes are connected (some may be left idle with no connectivity), and to which PBSS each node belongs. Each PBSS is assigned a radio channel of operation, and the network node within the PBSS that is the controller (the PCP) is identified. The exact nature of the algorithms/heuristics 112A, 112B, 112C is outside the scope of this disclosure, but each could be simple as a set of empirical rules or could be highly advanced using, for example, graph theory to generate a graph meeting predetermined objectives. A simulator unit 116 receives the PBSS designs from the respective design algorithms/heuristics. The simulator unit is operable to calculate the link data rates of the mesh for links that interconnect network nodes in the defined PBSSs, to consider the likelihood of interference between links, and, given the expected traffic rates and characteristics at each traffic source to the mesh, together with the identity of the associated target network node, to assess the performance against the design objectives. A comparison unit 118 weights the figures of merit produced by the simulator unit, and is operable to determine which PBSS design is best suited to meeting the predetermined criteria. The comparison unit 118 has an output 120 from which the chosen PBSS design is provided to a routing calculation agent.

In an alternative example, a single design algorithm/heuristic is operated by the design unit 112. The results of the design algorithm/heuristic are produced by the simulator unit 116, and used in future operations of the design algorithm/heuristic.

Figure 9 illustrates the interaction of the PBSS designer 110 with a routing calculation agent 122 and network nodes 124. As described above, the PBSS designer 110 provides the routing calculation agent 122 with a definition of the PBSSs for the mesh network. The routing calculation agent 122 determines routing for data being transferred across the mesh network and PBSSs defined therein. The routing agent 122 provides routing data and the local PBSS designs to each network node 124 for use thereby in the IEEE 802.11 ad MAC operations and the routing of data packets being transferred across the mesh network.

Each network node 124 may include a plurality of communications modules 126.

The communication modules 126 provide respective media access control/physical level functions (MAC/PHY) of the network node 124.

As an alternative, Figure 10 illustrates the interaction of the PBSS designer 130 with a multitude of routing calculation agents 132 and network nodes 134, with preferably one network node per routing agent. The PBSS designer 130 provides each routing calculation agent 132 with a definition of the local PBSSs involving IEEE 802.11 ad STAs of the associated network node. The routing agent 132 provides routing data and the local PBSS designs to the associated network node 134 for use thereby in the IEEE 802.11 ad MAC operations and the routing of data packets being transferred across the mesh network. This enables the operation of a distributed routing algorithm. The routing agent may be co-located with the network node.

The PBSS designer and/or the routing agent(s) may be implemented using a software defined network (SDN) paradigm to control the network node devices.

Embodiments of the present invention are able to provide improved PBSS definition performance, improved PBSS definitions and improved routing for a mesh communications network.

Claims (28)

CLAIMS:

1. A method of managing data transfer in a wireless mesh communications network which comprises a first plurality of network node devices each having a transceiver unit, a second plurality of wireless communications links which interconnect the transceiver units of the network node devices, a network definition agent, and a routing agent, the network node devices being arranged in an existing physical topology, the method comprising: at the network definition agent of the wireless mesh communications network: determining a sub-network within the wireless mesh communications network, the sub-network having a third plurality of transceiver units chosen from transceiver units of the first plurality of network node devices, the third plurality of transceiver units being interconnected by a fourth plurality of wireless communications links chosen from the second plurality of communications links, the sub-network being defined as at least a part of the existing physical topology of the wireless mesh communications network, and being determined in dependence upon at least one predetermined metric for the existing physical topology of the wireless mesh communications network; designating one of the transceiver units of the third plurality of transceiver units as a control unit for the sub-network; providing sub-network information defining the sub-network and control unit to the routing agent of the wireless mesh communications network; and at the routing agent of the wireless mesh communications network: receiving sub-network information from the network definition agent; defining a routing table for the wireless mesh communications network using the sub-network information.

2. A method as claimed in claim 1, wherein the network comprises a plurality of switches, and a routing table is provided for each such switch.

3. A method as claimed in claim 1 or 2, wherein the network definition agent is provided by a discrete dedicated unit.

4. A method as claimed in claim 1 or 2, wherein the network definition agent is distributed across multiple elements of the network.

5. A method as claimed in claim 1 or 2, wherein the network definition agent is distributed across multiple elements inside and/or outside of the network.

6. A method as claimed in any one of claims 1 to 5, wherein the routing agent is provided by a discrete dedicated unit.

7. A method as claimed in any one of claims 1 to 5, wherein the routing agent is distributed across multiple elements of the network.

8. A method as claimed in any one of claims 1 to 5, wherein the routing agent is distributed across multiple elements inside and/or outside of the network.

9. A method as claimed in any one of the preceding claims, wherein at least one of the first plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

10. A method as claimed in claim 10, wherein each of the first plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

11 .A method as claimed in claim 9 or 10, wherein the respective directions of operation are substantially mutually perpendicular.

12. A method as claimed in any one of the preceding claims, wherein the third plurality of transceiver units is a subset of the transceiver units of the first plurality of network node devices.

13. A method as claimed in any one of the preceding claims, wherein the fourth plurality of communications links is a subset of the second plurality of communications links.

14. A wireless mesh communications network which comprising: a first plurality of network node devices each having a transceiver unit; a second plurality of wireless communications links which interconnect the transceiver units of the network node devices in an existing physical topology; a network definition agent; and a routing agent, wherein the network definition agent comprises: a determination unit operable to determine a sub-network within the wireless mesh communication network in dependence upon at least one predetermined metric for the existing physical topology of the wireless mesh communications network, the sub-network having a third plurality of transceiver units chosen from transceiver units of the first plurality of network node devices, the third plurality of transceiver units being interconnected by a fourth plurality of wireless communications links chosen from the second plurality of communications links, the sub-network being defined as at least a part of the existing physical topology of the wireless mesh communications network; a designation unit operable to designate one of the network node devices of the third plurality of network node devices as a control unit for the sub-network; and an output unit operable to provide sub-network information defining the sub-network and control unit to the routing agent, and wherein the routing agent comprises: an input unit operable to receive sub-network information from the network definition agent; and a routing unit operable to define a routing table for the wireless mesh communications network using the sub-network information.

15. A network as claimed in claim 14, further comprising a plurality of switches, and a routing table is provided for each such switch.

16. A network as claimed in claim 14 or 15, wherein the network definition agent is provided by a discrete dedicated unit.

17. A network as claimed in claim 14 or 15, wherein the network definition agent is distributed across multiple elements of the network.

18. A network as claimed in claim 14 or 15, wherein the network definition agent is distributed across multiple elements inside and/or outside of the network.

19. A network as claimed in any one of claims 14 to 18, wherein the routing agent is provided by a discrete dedicated unit.

20. A network as claimed in any one of claims 14 to 18, wherein the routing agent is distributed across multiple elements of the network.

21. A network as claimed in any one of claims 14 to 18, wherein the routing agent is distributed across multiple elements inside and/or outside of the network.

22. A network as claimed in any one of claims 14 to 21, wherein at least one of the first plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

23. A network as claimed in claim 22, wherein each of the first plurality of network node devices includes a plurality of transceiver units having respective directions of operation.

24. A network as claimed in claim 22 or 23, wherein the respective directions of operation are substantially mutually perpendicular.

25. A network as claimed in any one of claims 14 to 24, wherein the third plurality of transceiver units is a subset of the transceiver units of the first plurality of network node devices.

26. A network as claimed in any one of claims 14 to 25, wherein the fourth plurality of communications links is a subset of the second plurality of communications links.

27. A method substantially as hereinbefore described with reference to the accompanying drawings.

28. A wireless mesh network substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.