Patent Application
20060146730
1. Field of the Invention:
The present invention relates to a system and method for a multicast architecture for wireless mesh networks.
2. Description of the Related Art:
Wireless communication networks, such as mobile wireless telephone networks, have become increasingly prevalent over the past decade. These wireless communications networks are commonly referred to as “cellular networks”, because the network infrastructure is arranged to divide the service area into a plurality of regions called “cells”. A terrestrial cellular network includes a plurality of interconnected base stations, or base nodes, that are distributed geographically at designated locations throughout the service area. Each base node includes one or more transceivers that are capable of transmitting and receiving electromagnetic signals, such as radio frequency (RF) communications signals, to and from mobile user nodes, such as wireless telephones, located within the coverage area. The communications signals include, for example, voice data that has been modulated according to a desired modulation technique and transmitted as data packets. As can be appreciated by one skilled in the art, network nodes transmit and receive data packet communications in a multiplexed format, such as time-division multiple access (TDMA) format, code-division multiple access (CDMA) format, or frequency-division multiple access (FDMA) format, which enables a single transceiver at a first node to communicate simultaneously with several other nodes in its coverage area.
In recent years, a type of mobile communications network known as an “ad-hoc” network has been developed. In this type of network, each mobile node is capable of operating as a base station or router for the other mobile nodes, thus eliminating the need for a fixed infrastructure of base stations.
More sophisticated ad-hoc networks are also being developed which, in addition to enabling mobile nodes to communicate with each other as in a conventional ad-hoc network, further enable the mobile nodes to access a fixed network and thus communicate with other mobile nodes, such as those on the public switched telephone network (PSTN), and on other networks such as the Internet. Details of these advanced types of ad-hoc networks are described in U.S. patent application Ser. No. 09/897,790 entitled “Ad Hoc Peer-to-Peer Mobile Radio Access System Interfaced to the PSTN and Cellular Networks”, filed on Jun. 29, 2001, in U.S. patent application Ser. No. 09/815,157 entitled “Time Division Protocol for an Ad-Hoc, Peer-to-Peer Radio Network Having Coordinating Channel Access to Shared Parallel Data Channels with Separate Reservation Channel”, filed on Mar. 22, 2001, and in U.S. patent application Ser. No. 09/815,164 entitled “Prioritized-Routing for an Ad-Hoc, Peer-to-Peer, Mobile Radio Access System”, filed on Mar. 22, 2001, the entire content of each being incorporated herein by reference.
As can be appreciated by one skilled in the art, the nodes 102, 106 and 107 are capable of communicating with each other directly, or via one or more other nodes 102, 106 or 107 operating as a router or routers for packets being sent between nodes, as described in U.S. patent application Ser. Nos. 09/897,790, 09/815,157 and 09/815,164, referenced above.
As shown in
Each node 102, 106 and 107 further includes a memory 114, such as a random access memory (RAM) that is capable of storing, among other things, routing information pertaining to itself and other nodes in the network 100. As further shown in
Multicasting is a more efficient method of supporting group communication than unicasting or broadcasting, as it allows transmission and routing of packets to multiple destinations using fewer network resources. With the advent of widespread deployment of wireless networks, the fast-improving capabilities of mobile devices, and an increasingly sophisticated mobile work force worldwide, content and service providers are increasingly interested in supporting multicast communications over wireless networks. As more and more applications and network control protocols require multicast support, an efficient multicast architecture for wireless multi-hop mesh networks is needed.
Multicast architecture for wired networks has been designed in recent decades. However, no multicast architecture for wireless multi-hop mesh networks has been proposed and deployed. Due to the unique characteristics of wireless multi-hop networks, the multicast architecture for wired networks can not be directly extended to wireless multi-hop networks.
The capacity of pure multi-hop wireless ad hoc networks diminishes as the number of nodes increases in a network as described by P. Gupta and P. R. Kumar in “The Capacity of Wireless Networks”, IEEE Transactions on Information Theory, Issue 2, March 2000. In order to increase the capacity of multi-hop wireless ad hoc networks, fixed infrastructure nodes may be introduced into the network, as described by P. Gupta and P. R. Kumar in “The Capacity of Wireless Networks”, IEEE Transactions on Information Theory, Issue 2, March 2000, and by M. J. Miller, W. D. List and N. H. Vaidya in “A Hybrid Network Implementation to Extend Infrastructure Reach”, Technical Report, Jan. 2003. Large scale multi-hop wireless mesh networks deploy infrastructure nodes such as an Internet Access Point (LAP) to expand the capacity of the mesh networks, and to provide access to the global internet. Multiple IAPs are connected to each other via wired or fixed wireless links through an edge router that is connected to the global internet. In the wireless domain, each routable wireless device can use the multicast routing protocol to join the multicast tree and support the multicast application. However, the multicast routing protocol designed for multi-hop wireless networks can not enable all these devices to join the global internet multicasting architecture.
The proposed multicast architecture enables the mesh networks to join the global multicast groups seamlessly, and extend the multicast support to any routable or non-routable devices in the wireless mesh networks.
The present invention provides a system and method for enabling mesh networks to join the global multicast group seamlessly, and extend the multicast support to any routable or non-routable devices in the wireless mesh networks. The proposed multicast architecture for the multi-hop wireless mesh networks addresses a very important but never discussed and studied problem for wireless mesh network to efficiently support multicast applications. The proposed multicast architecture for the multi-hop wireless mesh networks enables the mesh networks to join the global multicast group seamlessly, and extend the multicast support to any routable or non-routable devices in the wireless mesh networks.
These and other objects, advantages and novel features of the invention will be more readily appreciated from the following detailed description when read in conjunction with the accompanying drawings, in which:
In the proposed architecture, the IAP is deployed as the proxy device for all the wireless devices that are using this IAP to access the global internet. These wireless devices are referred to as being associated with the IAP. The IAP runs the group management protocol with an internet edge router to register the multicast groups for the devices associated with it. When a device is interested in a multicast group, it notifies its associated IAP about the multicast group address. The IAP will run the network group management protocol to register the multicast group to the internet edge router, which in turn can join the global internet multicast group by running the wired multicast routing protocol. At the same time, within the wireless mesh network domain, each device runs the wireless multicast routing protocol to form a multicast tree among the multicast group members including the IAP as the multicast group forwarding node. Hence, the wireless multicast routing domain can be connected to the global internet multicast routing domain to enable efficient multicast traffic delivery anywhere.
This architecture can be further extended in the wireless domain to provide multicast supporting capability for wireless devices that are not routable devices. “Routable” means that the device is running routing protocols including unicast and multicast routing protocols; “non-routable” means that the device is not running any routing protocols. For a non-routable device, in order to join the multi-hop wireless mesh network, it has to be proxied by a routable device in the wireless mesh network. In the proposed architecture, the network group management protocol is run between the non-routable device and the routable device. Therefore, the multicast group that the non-routable device is interested in can be registered in the routable device. The routable device can represent the non-routable device to join the multicast group communication via the wireless multicast routing protocol, and forward the multicast traffic to and from the network for the non-routable device. The wireless multicast routing protocol forms a multicast tree among the multicast routable devices (which are multicast group members or proxying for non-routable multicast group members) including the IAP as the multicast group forwarding node. The IAP is informed by the multicast routable devices about the multicast group that the device is interested in. Therefore, the LAP runs the network group management protocol to register the multicast group to the internet edge router, which in turn can join the global internet multicast group by running the wired multicast routing protocol.
An example of the multicast architecture for multi-hop wireless mesh networks is shown in
Although only a few exemplary embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.
