The price of certainty: "waterslide curves" and the gap to capacity

The classical problem of reliable point-to-point digital communication is to achieve a low probability of error while keeping the rate high and the total power consumption small. Traditional information-theoretic analysis uses explicit models for the communication channel to study the power spent in transmission. The resulting bounds are expressed using `waterfall' curves that convey the revolutionary idea that unboundedly low probabilities of biterror are attainable using only finite transmit power. However, practitioners have long observed that the decoder complexity, and hence the total power consumption, goes up when attempting to use sophisticated codes that operate close to the waterfall curve. This paper gives an explicit model for power consumption at an idealized decoder that allows for extreme parallelism in implementation. The decoder architecture is in the spirit of message passing and iterative decoding for sparse-graph codes, but is further idealized in that it allo...

• Type: Journal
• Year: 2008
• Where: CORR
• Authors: Anant Sahai, Pulkit Grover
• Keywords: CORR 2008, Education, Explicit Model, Total Power, Total Power Consumption