Capacity Region Of Channels Research Articles

Outer bounds on the capacity of interference channels (Corresp.)

New outer bounds are demonstrated for the capacity regions of discrete memoryless interference channels and Gaussian interference channels. The bound for discrete channels coincides with the capacity region in special cases. The bound for Gaussian channels improves previous knowledge when the interference is of medium strength.

A strong outer bound to the capacity region for multiple access channels (Corresp.)

Arimoto's converse to the coding theorem for discrete memoryless channel is extended to multiple access channels. The strong outer bound to the capacity region for multiple access channels that results is described analytically and graphically.

Partial feedback for two-way and broadcast channels

Two examples are presented showing that partial feedback can increase the capacity regions of broadcast channels and also the capacity regions even of those two-way channels which give equal outputs on both terminals.

Two-user interference channels with correlated information sources

Inner and outer bounds on the capacity region of two-user discrete memoryless interference channels (IFC) are obtained in the communication situation where private messages are sent by each sender as well as a common message by both senders to its corresponding receiver. A limiting expression for the capacity region is also derived. Special cases of the IFC are considered.

An outer bound to the capacity region of broadcast channels (Corresp.)

An outer bound to the capacity region of broadcast channels for the transmission of separate messages is derived. This bound improves upon Cover's outer bound by taking into consideration the total throughput information rate and the fact that the capacity region depends only on the marginal transition probabilities.

Interference channels

An interference channel is a communication medium shared by M sender-receiver pairs. Transmission of information from each sender to its corresponding receiver interferes with the communications between the other senders and their receivers. This corresponds to a frequent situation in communications, and defines an M -dimensional capacity region. In this paper, we obtain general bounds on the capacity region for discrete memoryless interference channels and for linear-superposition interference channels with additive white Gaussian noise. The capacity region is determined in special cases.

The capacity region of a channel with s senders and r receivers

The study of multi-way channels was initiated by Shannon in his basic paper “Two-way communication channels” ( Shannon, 1961 ). Ahlswede (1971b) has defined and classified multi-way channels of various kinds and proved simple characterizations for the capacity regions of channels with (a) two senders and one receiver, and (b) three senders and one receiver. Subsequently, Ahlswede (1974) found a new approach to the coding problem for a channel with two senders and one receiver which led to an alternative characterization of the capacity region of this channel. This approach seems to be more canonical than the earlier one, and was used successfully in determining the capacity region of a channel with two senders and two receivers in case both senders send messages simultaneously to both receivers ( Ahlswede, 1974 ). In the earlier paper, Ahlswede conjectured that the results of that paper would hold for any channel with s ⩾ 2 senders and one receiver. A conjecture of the later paper was that its results would hold for any channel with s ⩾ 2 senders and r ⩾ 1 receivers in case all senders send independent messages simultaneously to all receivers. In this paper, we have proved the latter conjecture to be true. The characterization we get for the special case s = 3 and r = 1 is different from that of Ahlswede's (1971b) earlier paper. All of our results are obtained under the assumption of independent sources.

On a problem by Ahlswede regarding the capacity region of certain multiway channels

A new Fano-type estimate is proved for multiway channels. It yields upper bounds on the numbers of codewords and the products of these numbers in a code for a channel with s senders and r receivers in the case all senders send messages simultaneously to all receivers. The result is based on a new approach, which makes an approximation argument previously used by Ahlswede (1971b) and Ulrey (1974) unnecessary. It also leads to better Fano-estimates than the ones obtained by these authors. Our approach is canonical for weak converses of coding theorems for multiway channels and applies also in other communication situations.