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Cross-layer design is a suitable approach that can address some of throughput challenges for future multimedia applications. In this regard, effective capacity concept offers a suitable metric to assess the implications that physical layer design may have on link layer performance. However, most reported studies in this aspect consider the case of downlink scenario for convenience multiple input multiple...
While buffer-aided relaying improves the diversity of a multi-hop network, its deployment introduces time-delays, thus rendering buffering unreliable for delay-intolerant applications. To alleviate excessive delays, various studies propose delayaware protocols, but at the expense of reduced diversity, and consequently, increased outage probability. Attempts to maintain the diversity of the system...
This paper concerns multiple time delays in power and rate control for wireless communication networks with external disturbance. Based on the mathematical state-space model established for the wireless communication networks with state delay and input delay, a compensation algorithm for multiple time delays of general form model is researched and it can be applied into our model. An optimal tracking...
In this paper, we investigate the performance of the wiretap Rayleigh fading channel in the presence of statistical delay constraints. We invoke tools from stochastic network calculus to derive probabilistic bounds on the delay. This method requires a statistical characterization of the wiretap fading service process, which we derive in closed form. We then validate these analytical bounds via simulations...
This paper investigates the feedback delay effects on opportunistic relay selection strategy. The investigation considers a dual-hop multiple half/full-duplex two-way wireless relaying network in the system model. The selection strategy is based on the sum-rate of user-pair and related relay terminal. According to Monte-Carlo simulation results, sum-rate based relay selection strategy achieves cooperative...
Reliable, ad hoc communication among multiple users is a crucial objective in complex tactical scenarios. A major challenge is that synchronization mechanisms (such as GPS) are intermittent and fixed centralized coordinators (e.g., base stations) are infeasible. Classical approaches to multiuser communications relying on tight time synchronization and/or power control are impractical in such scenarios...
In cellular networks, under ARQ and SINR model of transmission, the effective downlink rate of packet transmission is the reciprocal of the expected delay (number of retransmissions needed till success). We define the cellular network capacity as the ratio of the basestation (BS) density and the expected delay. Exact characterization of this natural and practical but non-trivial (because of SINR temporal...
In this paper, a new scheme for delay parameters measurement in time division multiplexing (TDM) fiber optic interferometric sensor (FOIS) network is proposed. This scheme provides a solution of delay parameters measurement through the variance vector of the reshaped original data. By calculating the correlation between the variance vector and the system's pulse template vector, the scheme is capable...
In this paper, a high efficient differential chaos shift keying (DCSK) based on frequency division multiplexing (FDM) communication system, namely FDM-HEDCSK is proposed. The scheme has two branches and a serial-parallel converter to achieve four attainable bit rates and improve communication security in comparison to DCSK. In this scheme, the combination of two chaos signals is used as the reference...
Orthogonal Frequency Division Multiplexing (OFDM) has been widely implemented in modern wireless communication systems because of its robustness against frequency selective wireless channels. To coherently detect signals, estimating the Channel State Information (CSI) is crucial for receiver design. Channel estimation is also necessary for Reference Signal Receive Quality (RSRQ) measurement, interference...
We present a distributed algorithm for joint power control, routing and scheduling in multihop wireless networks. The algorithm also provides for Quality of Service (QoS) guarantees, namely, end-to-end mean delay guarantees and hard deadline guarantees, for different users. It is easily implementable and works by giving local dynamic priority to flows requiring QoS, the priority being a function of...
This paper presents speech enhancement using fixed and adaptive beamforming techniques to improve quality of speech signal in noisy environment. Microphone arrays provide a means of enhancing a desired signal in the presence of corrupting noise sources using spatial filtering. In this paper, Delay and Sum Beamformer (DSB) and Generalized Side lobe Canceller (GSC) beamformer are implemented using microphone...
In this paper, the estimation of a narrowband time-varying channel under the practical assumptions of finite block length and finite transmission bandwidth is investigated. It is shown that the signal after passing through a time-varying narrowband channel, under these assumptions, reveals a particular low-rank structure. The rank in this structure is governed by the number of dominant paths in the...
The paper proposes a convex combination fusion function based on a sigmoid function for the estimation of the a priori SNR in a speech enhancement framework with critical frequency band processing. The proposed method does not only eliminate the one frame delay generated by the well-known decision directed approach but also increases the adaptation speed during abrupt changes in the SNR estimation...
Previous work has noted the distinct characteristics of vertically and horizontally polarized multipath components for indoor non-line-of-sight (NLOS) environments. Using measured data, the receiver signal-to-noise ratios (SNRs) for coherent and noncoherent combining of the co- and cross-polarized multipath components are compared to those obtained with omnidirectional reception for vertical or horizontal...
The Cognitive Radio (CR) is an emerging technology for modern wireless communication system that offers a great solution to scarcity of radio spectrum. The Cognitive Radio Network (CRN) is an intelligent wireless communication organization that is aware of its environment. Here, heterogeneous nodes meet spectrum sensing challenges due to the variation of transmission power, spectrum allocation and...
Wireless sensor network consists of independent device spatially distributed in the wireless network with sensor that observes the environment conditions. The cluster based transaction is the gateway of wireless medium and distributed nodes has limitations in power supply. Packet scheduling is the mandatory process in wireless networks to balance the network and minimize the end delay. In energy efficient...
In orthogonal frequency-division multiplexing (OFDM) systems, the broadband channel features sparse structure in delay domain. By fully exploiting the sparse structure of channels, transform domain (TD) channel estimation (CE) methods such as discrete Fourier transform (DFT) method and compressed sensing (CS)-based methods can greatly upgrade the performance of channel estimation. When the paths of...
In the Wireless sensor network small size based and low power sensor nodes spreads over a complete geographical area which is connected to each other for performing or control the applications. Every application requires a control center which collects the aggregates data from all sensor nodes. Data aggregation is used for compress data and also for power saving which gives time efficient method for...
In Battery-Free Wireless Sensor Network (BF-WSN), nodes are powered by the energy harvested from ambience instead of batteries. The nodes may frequently suffer from insufficient energy so that they need to alternate normal operation (such as transmitting/receiving, etc.) with harvesting energy. This brings in extra packet delay for the nodes to deliver data to the sink(s). Therefore, delivering data...
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