Taktiska Ad hoc-nät -- Broadcast med adaptiv datatakt

Authors:

  • Anders Hansson
  • Jimmi Grönkvist

Publish date: 2009-11-06

Report number: FOI-R--2820--SE

Pages: 12

Written in: Swedish

Keywords:

  • Ad hoc networks
  • routing
  • broadcast
  • multicast
  • multi-rate

Abstract

Mobile ad hoc networks are wireless multi-hop radio networks that have the ability to dynamically adapt to changing conditions. A great tactical gain in ad hoc networks is that they can function independently of base stations and other fixed infrastructure if required. The technique is suitable both for vehicle-borne and hand-held devices. The Swedish Armed Forces has begun the acquisition and development of vehicle-borne ad hoc networks (GTRS) and later hand-held devices will also be of interest. In a fully mobile radio networks, there are no high antennas. Capacity is more limited because of the difficult propagation conditions compared to radio networks with base stations. It is therefore important that the radio network can manage available resources efficiently. In this report we give an overview of broadcast and multicast, with a focus on how adaptive data rate can be utilised. Broadcast in multi-hop networks means that one transmit to all, while multicast means that one transmit to a selected group in the network. This type of traffic is expected to be a very large part of the total traffic in tactical mobile radio networks. Unfortunately, this is not the case in commercial radios and there is a need for separate solutions for tactical networks. With adaptive data rate, we can dynamically trade range for capacity in the ad hoc network. A major benefit is that nodes close to each other can communicate at high rate, another advantage is that the network can be prevented from falling apart by allowing a reduced capacity on some links. This is relatively straightforward to apply in cellular systems, but is more complex for ad hoc networks, especially for broadcast traffic. We summarize briefly the research for year 2009 in the project "Communications for Voice and Data-Based Command and Control" for this problem area. Four methods to utilize adaptive data rate in tactical ad hoc networks with broadcast traffic has been evaluated.

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