Generalizing capacity: new definitions and capacity theorems for composite channels

We consider three capacity definitions for composite channels with channel side information at the receiver. A composite channel consists of a collection of different channels with a distribution characterizing the probability that each channel is in operation. The Shannon capacity of a channel is the highest rate asymptotically achievable with arbitrarily small error probability. Under this definition, the transmission strategy used to achieve the capacity must achieve arbitrarily small error probability for all channels in the collection comprising the composite channel. The resulting capacity is dominated by the worst channel in its collection, no matter how unlikely that channel is. We, therefore, broaden the definition of capacity to allow for some outage. The capacity versus outage is the highest rate asymptotically achievable with a given probability of decoder-recognized outage. The expected capacity is the highest average rate asymptotically achievable with a single encoder an...

• Type: Journal
• Year: 2010
• Where: TIT
• Authors: Michelle Effros, Andrea J. Goldsmith, Yifan Liang
• Keywords: Capacity Definitions, Composite Channel, Education, Small Error Probability, TIT 2010