On the Capacity of the Half-Duplex Diamond Channel

Abstract

In this paper, a dual-hop communication system composed of a source S and a destination D connected through two non-interfering half-duplex relays, R1 and R2, is considered. In the literature of Information Theory, this configuration is known as the diamond channel. In this setup, four transmission modes are present, namely: 1) S transmits, and R1 and R2 listen (broadcast mode), 2) S transmits, R1 listens, and simultaneously, R2 transmits and D listens. 3) S transmits, R2 listens, and simultaneously, R1 transmits and D listens. 4) R1, R2 transmit, and D listens (multiple-access mode). Assuming a constant power constraint for all transmitters, a parameter $\Delta$ is defined, which captures some important features of the channel. It is proven that for $\Delta$=0 the capacity of the channel can be attained by successive relaying, i.e, using modes 2 and 3 defined above in a successive manner. This strategy may have an infinite gap from the capacity of the channel when $\Delta \ne$0. To achieve rates as close as 0.71 bits to the capacity, it is shown that the cases of $\Delta$>0 and $\Delta$<0 should be treated differently. Using new upper bounds based on the dual problem of the linear program associated with the cut-set bounds, it is proven that the successive relaying strategy needs to be enhanced by an additional broadcast mode (mode 1), or multiple access mode (mode 4), for the cases of $\Delta$<0 and $\Delta$>0, respectively. Furthermore, it is established that under average power constraints the aforementioned strategies achieve rates as close as 3.6 bits to the capacity of the channel.

25 pages, 2 figures, submitted to IEEE Transactions on Information Theory

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• Wireless Network Information Flow: A Deterministic Approach
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• On the Capacity of the Half-Duplex Diamond Channel
• DMT of Multi-hop Cooperative Networks - Part II: Half-Duplex Networks with Full-Duplex Performance
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Cited by in corpus (8)

• On the Capacity of the Half-Duplex Diamond Channel
• Gaussian Half-Duplex Relay Networks: improved constant gap and connections with the assignment problem
• On the Optimality of Simple Schedules for Networks with Multiple Half-Duplex Relays
• On Gaussian Half-Duplex Relay Networks
• The Approximate Optimality of Simple Schedules for Half-Duplex Multi-Relay Networks
• Full-Duplex Relaying with Half-Duplex Relays
• On the Achievable Rates of Multihop Virtual Full-Duplex Relay Channels
• Best Relay Selection in Gaussian Half-Duplex Diamond Networks