Search results for "Computer Science::Information Theory"
showing 10 items of 272 documents
A contention-based multiple access protocol in cooperative wireless networks
2010
Cooperative communication has emerged as a promising technique to enhance system performance in wireless networks. This paper proposes a contention-based cooperative multiple medium access control protocol by means of multiple retransmissions of the same packet from different relay nodes. The proposed scheme exploits cooperative communication capability not only from time diversity derived from multiple temporal transmissions but also spatial diversity derived from distributed multiple relays. A Markov chain is introduced to analyze the throughput performance of the proposed cooperative scheme. The performance evaluation of the protocol is validated and compared with non-cooperative ARQ pro…
A Trajectory-Driven SIMO mm-Wave Channel Model for a Moving Point Scatterer
2021
In this paper, we propose a trajectory-based three-dimensional (3D) non-stationary channel model for a millimeter wave (mm-Wave) single-input multiple-output (SIMO) system. The proposed channel model is designed to capture the mobility of a moving point scatterer in an indoor environment. We derive the expression of the time-variant (TV) channel transfer function (CTF). We study the TV Doppler characteristics of the channel, such as the TV Doppler power spectrum and the TV mean Doppler shift. To validate the proposed channel model, we performed a measurement campaign in an indoor environment using a software defined radar operating at 24 GHz. As a moving object, we consider a single swingin…
A non-stationary multipath fading channel model incorporating the effect of velocity variations of the mobile station
2014
A standard assumption in mobile fading channel modelling is that the mobile station (MS) moves along a straight line with constant speed. In practice, this assumption is violated in most propagation scenarios. For the development of more realistic channel models, it is therefore important to relax this restriction by allowing the MS to change its velocity. In this paper, we study the effect of velocity changes on the statistical properties of multipath fading channels. Expressions will be derived for the local autocorrelation function (ACF), the Wigner-Ville spectrum, the average Doppler shift, and the Doppler spread. Our findings show that a variation of the speed and/or the direction of t…
The Influence of LOS Components on the Statistical Properties of the Capacity of Amplify-and-Forward Channels
2009
Also available from publisher: http://dx.doi.org/10.4236/wsn.2009.11002 Amplify-and-forward channels in cooperative networks provide a promising improvement in the network coverage and system throughput. Under line-of-sight (LOS) propagation conditions in such cooperative networks, the overall fading channel can be modeled by a double Rice process. In this article, we have stud-ied the statistical properties of the capacity of double Rice fading channels. We have derived the analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level- crossing rate (LCR), and average duration of fades (ADF) of the channel capacity. The obtained results ar…
Performance evaluation of sum-of-cisoids Rice/Rayleigh fading channel simulators with respect to the bit error probability
2014
Sum-of-cisoids (SOC) processes provide an important framework for the modeling and simulation of multipath fading channels. In this paper, we analyze the performance of SOC Rice/Rayleigh narrowband fading channel simulators with respect to the bit error probability (BEP) of quadrature phase shift keying (QPSK) and differential phase shift keying (DPSK) systems with both coherent and noncoherent demodulation. For the BEP of coherent QPSK and DPSK, exact analytical expressions are derived, which provide insight into the influence of the number of propagation paths and the path gains on the system performance. It will be shown that at least 10 multipath components are required to guarantee tha…
Super-orthogonal space-time trellis codes with differential phase modulation for noncoherent mobile communication systems
2010
In this paper, we show how to design super-orthogonal space-time trellis codes (SOSTTCs) using the differential binary phase-shift keying (PSK) modulation for noncoherent communication systems, for which the knowledge of the channel state information (CSI) at the receiver is not necessary. Moreover, a new decoding algorithm with reduced decoding complexity is proposed. In all simulations, a geometric two-ring channel model is employed to evaluate the performance of the SOSTTCs. The simulation results show that the proposed decoding algorithm has the same decoding performance compared with the traditional decoding strategy, while the new algorithm reduces significantly the overall computing …
Reliable Underlay Device-to-Device Communications on Multiple Channels
2019
Device-to-device (D2D) communications provide a substantial increase in spectrum usage and efficiency by allowing nearby users to communicate directly without passing their packets through the base station (BS). In previous works, proper channel assignment and power allocation algorithms for sharing of channels between cellular users and D2D pairs, usually require exact knowledge of the channel-state-information (CSI). However, due to the non-stationary wireless environment and the need to limit the communication and computation overheads, obtaining perfect CSI in the D2D communication scenario is generally not possible. In this work, we propose a joint channel assignment and power allocati…
Uplink DPCCH Gating of Inactive UEs in Continuous Packet Connectivity Mode for HSUPA
2007
In order to further improve the packet performance in the UMTS FDD system, uplink dedicated physical control channel (DPCCH) gating as a scheme is proposed in 3GPP under the work item "continuous connectivity for packet data users". In this paper, the uplink DPCCH gating concept is described and analyzed on both a qualitative and a quantitative level. And the system performance of different gating patterns used in the scheme was investigated by analytical prediction and system level simulations with different channel profiles. As shown, the selection of the gating pattern has a significant influence on the system performance, which is correlated with the uplink data transmission activity an…
Energy-Efficient Binary Power Control with Bit Error Rate Constraint in MIMO-OFDM Wireless Communication Systems
2012
Motivated by the demand for energy efficiency improvement in mobile communication industry, we explore an idea of optimizing energy efficiency for MIMO-OFDM wireless communication systems while maintaining users' quality of service (QoS) requirement. Based on the binary power control scheme,a power allocation criterion for energy efficiency optimization is derived under the total power constraint. From a bit error rate (BER) point of view, a protection constraint is configured to guarantee the system QoS. With the aim of energy efficiency optimization under QoS guarantee in MIMO-OFDM wireless communication systems, an energy-efficient binary power control with BER constraint (EBPCB) algorith…
Keynote talk 3: From basics to advanced modelling and simulation techniques for mobile radio channels
2011
From the earliest beginnings of mobile communications to the present time, there has always been a high demand for realistic mobile radio channel models. This demand is driven by the fact that channel models are indispensable for the performance evaluation, parameter optimisation, and test of mobile communication systems. Channel modelling and simulation techniques are therefore of great importance for electronics and telecommunication engineers who are involved in the development of present and future mobile communication systems. This presentation will start with a review of the basic principles of mobile radio channel modelling and gradually moves to more advanced modelling and simulatio…