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This work presents the results of development completed to date on a network configuration system for a Rapidly Deployable Radio Network (RDRN).

The Rapidly Deployable Radio Network is a high capacity rapidly deployable wireless ATM network comprised of switch and host nodes.

Research involving mobile ATM has only recently begun; therefore, literature in this area is scarce. Discussion of a wireless protocol stack is given in [1]. A tree based method for low overhead handoff with ATM is explained in [2]. An interesting mobile LAN ATM architecture is provided in [3]. Finally, [4] provides an analysis of switch buffer fill distribution in a mobile ATM environment.

The RDRN architecture is composed of three overlaid networks:

The network currently consists of two types of nodes, edge nodes (EN) and remote nodes (RN). Edge nodes reside on the edge of a wired network and provide access to the wireless network. The Edge Node components include the ATM switch, high speed radio, AX.25 packet radio for the low speed orderwire, GPS receiver, and an additional processor for the network configuration system. Host nodes or remote nodes (RN) consist of the above, but do not contain an ATM switch. The ENs and RNs also include a phased array steerable antenna. The RDRN uses position information from the GPS for steering antenna beams toward nearby nodes and nulls toward interferers, thus establishing the high capacity links.

The orderwire network uses a low power, omnidirectional channel, operating at 19200 bps, for signaling and communicating node locations to other network elements. The orderwire aids link establishment between the edge nodes and between the remote and edge nodes, tracking remote nodes and determining link quality. The orderwire operates over the packet radios and is part of a larger network configuration system. An example of the high speed and orderwire network topology is shown in Figure 1. In this figure, an EN serves as a link between a wired and wireless network, while the remaining ENs act as wireless switches. The protocol stack for the high speed network is shown in Figure 2.

Figure 1: Example Orderwire Topology.

Figure 2: High Speed Protocol Stack.

The focus of this paper is on the network configuration system and in particular on the orderwire. This includes protocol layer configuration, link quality, handoff, and host/switch assignment along with information provided by the GPS system such as position and time. The details of the high speed network will be covered in this paper only in terms of services required from, and interactions with, the network configuration system.

We will now provide a brief overview of the high speed protocol architecture for this wireless ATM network with the aim of identifying the requirements that each layer will have for the network configuration system. The physical layer includes all the hardware components such as the high speed radios, ATM switch, antennas, and additional processor for configuration and setup (orderwire) as well as the wireless connections. At this layer, the network configuration system is designed to determine an association of RNs to ENs which will provide a given QoS, and to establish the wireless (virtual fiber) connections. The data link layer will be adaptive to provide an appropriate degree of data rate versus reliability in order to properly support the various types of ATM traffic and will carry ATM end-to-end. In a PVC environment, the ATM layer network configuration system will automatically setup fully meshed PVC among all remote nodes, while in an SVC environment, the network configuration system will establish the switching VC between the host and switch. The Mobile IP layer, whose main function is to provide routing between subnetworks and service for TCP and UDP transport layers, requires information such as a RN's home agent and foreign agent for an Logical IP Subnet (LIS). The information required by the ATM, IP and TCP layers will be exchanged over the orderwire through special packet types.

The next section describes the network configuration protocol layers, packet types, and operation while Section 3: describes a virtual time mechanism for rapid network reconfiguration.

next up previous
Next: Network Configuration System Overview Up: A Control and Management Previous: A Control and Management

Steve Bush
Mon Aug 26 18:24:40 CDT 1996