Real-time multicast in wireless communications
Parallel and distributed real-time systems
Real-time multicast in wireless communication
ICPP '97 Proceedings of the international Conference on Parallel Processing
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L. K. Nahar and S. Bhattacharya Abstract: High-assurance is a collective term implying real-time, security, reliability and safety. We consider a load balancing utopia for dynamic media access control (MAC) in firmware controlled network media (e.g., wireless, optical network) which provides high-assurance. In a firmware controlled network, frequency and time-assignment can be embedded in the logical channel on the fly - that is, logical with various frequency, time and code assignments can be created and updated dynamically. Consequences are that, when high-assurance like real-time traffic is required, we can create additional logical channels to support it without leading to congestion on the existing logical channels.To support real-time traffic, direct logical channels can be created between source to destination. There is no need to go through existing multi-hop logical channels. This will satisfy the real-time delay-constraint imposed on the message. Likewise, failure of any link/channel can be taken into account in a similar fashion. For added fault-tolerance one can replicate redundant logical channels and thereby provide added degrees of reliability instead of having to send same message over and over again in redundant fashion on the same physical channel. For assuring security, multiple logical channels can be created which can support channel shift keying - a concept analogous to frequency shift keying (FSK) popular for radio networks.Note that all these capabilities are direct consequences of a firmware controlled network: where MAC layer can support dynamic behavior. Creation and update of logical channels can be supported for optical and wireless nehvork, which are firmware controlled. Hardware network, e.g., VLSI embedded or wireconnected, can not have these advantages.However, price paid is the added overhead of nehvork management. A close degree of synchronization must be maintained by the network manager. Our current research is investigating the trade-off between this performance overhead and benefits obtained. We believe for emerging wireless network this technique of firmvvare controlled MAC and dynamic network will help eliminate many of the traditional network design concerns, e.g., "HOTSPOT". If achieved this should be a breakthrough in nehvork technology arena since problems such as hotspot is known as performance killer in congested netvvorks: and although various techniques \\xre proposed to reduce hotspots. they. could never be completely. eliminated.