Thursday, 27 December 2007

Multihop Cellular Networks and ODMA

While going through September issue of IEEE Communications magazine, I came across Multihop Cellular Networks (MCNs). The concept sounded familiar and another article confirmed my suspicion. MCNs is similar to ODMA for those who remember the early 3GPP specs. ODMA or Opportunity Driven Multiple Access was revolutionary concept but it was too advanced for that time and the chipset (and battery) technology was not that advanced to have it implemented successfully.

The best place to understand ODMA is in 3GPP TR 25.924. Also see this.

So what exactly is multihop cellular network (MCN)?

To quote from IEEE Communications Magazine (Sep 07):

MCN incorporates the flexibility of ad hoc networking, while preserving the benefits of using an infrastructure.

The salient feature of MCN is that communications are not restricted to single hop; multihop transmissions are allowed.

The advantages of using MCN include capacity enhancement, coverage extension, network scalability, and power reduction. However, there are still a number of open research issues that need to be solved in order to provide efficient and effective multihop transmissions in cellular networks in the future.

From another article in the same issue:

Existing architectures and protocols proposed for MCNs are very diverse and different in several aspects. Relay Stations (RSs) can be preinstalled by network operators or simply be other idle MHs who are not transmitting their own data. Also, depending on how radio resources are allocated for routing paths of active connections, different protocols at the medium access control and routing layers can be designed. Radio resources forMobile Hosts (MHs) at different hops may be allocated in timedivision duplex (TDD) or frequency-divisionduplex (FDD) mode. Frequency bands other than the cellular frequency band may be used for relaying. Finally, advanced techniques using cooperative diversity can be employed to enhance network performance compared to simple relaying schemes.

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