Communication channel

About: Communication channel is a research topic. Over the lifetime, 137411 publications have been published within this topic receiving 1715077 citations. The topic is also known as: communication channel & communications channel.

Bandwidth- and power-efficient routing in linear wireless networks

Abstract: The goal of this paper is to establish which practical routing schemes for wireless networks are most suitable for power-limited and bandwidth-limited communication regimes. We regard channel state information (CSI) at the receiver and point-to-point capacity-achieving codes for the additive white Gaussian noise (AWGN) channel as practical features, interference cancellation (IC) as possible, but less practical, and synchronous cooperation (CSI at the transmitters) as impractical. We consider a communication network with a single source node, a single destination node, and N-1 intermediate nodes placed equidistantly on a line between them. We analyze the minimum total transmit power needed to achieve a desired end-to-end rate for several schemes and demonstrate that multihop communication with spatial reuse performs very well in the power-limited regime, even without IC. However, within a class of schemes not performing IC, single-hop transmission (directly from source to destination) is more suitable for the bandwidth-limited regime, especially when higher spectral efficiencies are required. At such higher spectral efficiencies, the gap between single-hop and multihop can be closed by employing IC, and we present a scheme based upon backward decoding that can remove all interference from the multihop system with an arbitrarily small rate loss. This new scheme is also used to demonstrate that rates of O(log N) are achievable over linear wireless networks even without synchronous cooperation.

A coding scheme for additive noise channels with feedback--II: Band-limited signals

Abstract: In Part I of this paper, we presented a scheme for effectively exploiting a noiseless feedback link associated with an additive white Gaussian noise channel with {\em no} signal bandwidth constraints. We now extend the scheme for this channel, which we shall call the wideband (WB) scheme, to a band-limited (BL) channel with signal bandwidth restricted to (- W, W) . Our feedback scheme achieves the well-known channel capacity, C = W \ln (1 +P_{u,v}/N_{0} W) , for this system and, in fact, is apparently the first deterministic procedure for doing this. We evaluate the fairly simple exact error probability for our scheme and find that it provides considerable improvements over the best-known results (which are lower bounds on the performance of sphere-packed codes) for the one-way channel. We also study the degradation in performance of our scheme when there is noise in the feedback link.

Capacity and error exponent for the direct detection photon channel. II

Abstract: For pt.I see ibid., vol.34, no.6, p.1449-61 (1980). The discussion of the capacity and error exponent of the direct detection optical channel is continued. The channel input in a T-second interval is a waveform satisfying certain peak and average power constraints for the optical signals. The channel output is a Poisson process with an intensity parameter that accounts for the dark-current component. An upper bound is obtained on the error exponent which coincides with the lower bound. Thus, this channel is one for which the error exponent can be known exactly. >

Periodic sequences with optimal properties for channel estimation and fast start-up equalization

Abstract: The problems of fast channel estimation and fast start-up equalization in synchronous digital communication systems are considered from the viewpoint of the optimization of the training sequence to be transmitted. Various types of periodic sequences having uniform discrete power spectra are studied. Some of them are new and may be generated with data sets commonly used in phase modulation systems. As a consequence of their power spectra being flat, these sequences ensure maximum protection against noise when initial equalizer settings are computed via channel estimates and noniterative techniques.

System and method for channel state related feedback in multi-user multiple-input-multiple-output systems

Abstract: System and method for dimension reduction and for channel and interference condition feedback in a Multi-User Multiple-Input-Multiple-Output (MU MIMO) wireless communication systems. The method for dimension reduction includes determining a number of virtual antennas,ν?K#191, for beamformees pertaining to a multi user (MU) transmission group, reducing the dimension of said matrix by selecting a sub-set of antennas or by Eigen mode selection and sending a reduced dimension candidate transmit beamforming matrix or an effective channel matrix to a beamformer. The method for channel and interference condition feedback Interference condition includes sending to a beamformee metric indicative of the interference level from other streams.