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.

Antecedents and performance implications of channel integration in foreign markets

Abstract: This study enhances our understanding of channel integration in foreign markets on two fronts. First, the eclectic approach to foreign entry mode, proposed by Hill, Hwang and Kim [1990] and Kim and Hwang [1992], is used to examine transaction-specific, organizational capability and strategic factors that influence channel choices in foreign markets. Empirical results based on survey of U.S. firms support the combined relevance of these factors in predicting the degree of channel integration. Second, the study empirically examines the performance consequences of channel integration. The results suggest that, although the degree of channel integration does not have a direct influence on channel performance, a contingency model based on the fit between the contextual factors and the actual channel choice is significantly related to performance in foreign markets.

Multiple media delivery network method and apparatus

Abstract: A multiple media system having a central site and a remote site for customizing video and audio presentations comprising a communications channel, a studio processor, a scheduling processor, a network processor, a transmitter, a communications processor, a video processor, and optionally a matrix switch, a cue processor, a matrix-switch processor and a system monitor. The studio processor generates one or more content data signals. The content data signals maybe analog or digital, and include text signals, phototext signals and/or audio signals. The scheduling processor generates a schedule data signal, which includes a unique identifier, accounting, administrative and scheduling data. The network processor generates a communication signal which includes the one or more content data signals and the schedule data signals formatted with the video signal. The transmitter transmits the communications signal over the communications channel. At the remote site the communications processor receives the communications signal and selects a first content data signal from the one or more content data signals. The video processor mixes the first content data signal with the video signal. The cue processor is coupled to network feed channel through a matrix switch. In response to detecting network-cue signals, the cue processor generates insertion signals. In response to the insertion-cue signals, the matrix processor controls the matrix switch routes the multiple media signal, which includes the video signal with the additional information from the content data signal, to a network communications channel.

Large system performance of linear multiuser receivers in multipath fading channels

Abstract: A linear multiuser receiver for a particular user in a code-division multiple-access (CDMA) network gains potential benefits from knowledge of the channels of all users in the system. In fast multipath fading environments we cannot assume that the channel estimates are perfect and the inevitable channel estimation errors will limit this potential gain. We study the impact of channel estimation errors on the performance of linear multiuser receivers, as well as the channel estimation problem itself. Of particular interest are the scalability properties of the channel and data estimation algorithms: what happens to the performance as the system bandwidth and the number of users (and hence channels to estimate) grows? Our main results involve asymptotic expressions for the signal-to-interference ratio of linear multiuser receivers in the limit of large processing gain, with the number of users divided by the processing gain held constant. We employ a random model for the spreading sequences and the limiting signal-to-interference ratio expressions are independent of the actual signature sequences, depending only on the system loading and the channel statistics: background noise power, energy profile of resolvable multipaths, and channel coherence time. The effect of channel uncertainty on the performance of multiuser receivers is succinctly captured by the notion of effective interference.

Using Orthogonal and Quasi-Orthogonal Designs in Wireless Relay Networks

Abstract: Distributed space-time coding was proposed to achieve cooperative diversity in wireless relay networks without channel information at the relays. Using this scheme, antennas of the distributive relays work as transmit antennas of the sender and generate a space-time code at the receiver. It achieves the maximal diversity when the transmit power is infinitely large. This paper is on the design of practical distributed space-time codes (DSTCs). We use orthogonal and quasi-orthogonal designs which are originally used in the design of space-time codes for multiple-antenna systems. It is well known that orthogonal space-time codes have full diversity and linear decoding complexity. They are particularly suitable for transmissions in the network setting using distributed space-time coding since their ldquoscale-freerdquo property leads to good performance. Our simulations show that they achieve lower error rates than the random code. We also compare distributed space-time coding to selection decode-and-forward using the same orthogonal designs. Simulations show that distributed space-time coding achieves higher diversity than selection decode-and-forward (DF) when there is more than one relay. We also generalize the distributed space-time coding scheme to wireless relay networks with channel information at the relays. Although our analysis and simulations show that there is no improvement in the diversity, in some networks, having channel information at the relays saves both the transmission power and the transmission time.

Dynamic channel selection scheme for IEEE 802.11 WLANs

Abstract: Disclosed is a method and system for dynamically selecting a communication channel between an access point (AP) and a plurality of stations (STAs) in an IEEE 802.11 wireless local area network (WLAN). The method includes the steps of: determining whether a new channel between the AP and STAs within a particular basic service set (BSS) is needed; requesting a channel signal quality measure to some of the plurality of stations by the AP; reporting a channel signal quality report back to the AP based on a received signal strength indication (RSSI) and a packet error rate (PER) of all channels detected by the stations within the BSS; selecting a new channel based on the channel quality report for use in communication between the AP and the plurality of stations.