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In this paper, we deploy a modified version of Shanno algorithm in order to optimize the bit error rate (BER) cost function using a nonlinear block optimization strategy for its minimization. The resulting algorithm is called the Block Shanno Minimum BER (BSMBER), which is conducted in the design of spatial multiuser receivers for orthogonal frequency division multiplexing (OFDM) system using multiple...
In this paper we proposed a novel self-organized message dissemination algorithm, namely the cluster-based broadcast (CB), for the emergency electronic brake light (EEBL) application in vehicular ad-hoc networks (VANET). The proposed cluster-based broadcast algorithm converts multihop broadcast message forwarding into multiple of single-hop broadcast clusters, which offers higher reliability, lower...
This paper studies the performance of orthogonal frequency division multiple access (OFDMA) in the multiuser multicarrier MIMO (M3) system for both uplink (UL) and down-link (DL) channels. We numerically quantify the performance gap between OFDMA and the optimal multicarrier solution. We also derive simple but near optimal algorithms to solve the generic OFDMA resource allocation problem in different...
In this paper, we present a new method to analyze the performance of automatic repeat request (ARQ) schemes in self-similar traffic for the future service-oriented Internet. Taking into account the self-similar traffic of a massive-scale wireless multimedia service, we build a batch arrival queueing model and suppose the batch size is a random variable following Pareto (c, alpha) distribution. Considering...
In this paper, we make an attempt to integrate the features of scalable video coding (SVC) into current OFDM based mobile communications systems for improving the broadcast data rates and to provide a better coverage. Several physical- and MAC-layer concepts that quality for the use in combination with SVC are evaluated. Space time coding in combination with single carrier frequency division multiplexing...
WLAN, based on the IEEE 802.11 standard has been extensively studied since its release. In addition to infrastructure access to WLAN, mesh networks currently attract a lot of attention. This comes from the envisioned advantages of wireless mesh networks, such as cheap installation costs, extended coverage, robustness, easy maintenance, and self-configuration possibilities. In this paper we focus on...
In this paper, we aim to provide an analytical modeling of cyclic delay diversity in an OFDMA based system. Cyclic delay diversity is a low complexity spatial diversity scheme where multiple transmit antennas transmit delayed versions the same signal. While CDD increases the frequency selectivity, the reduced coherence bandwidth resulted in higher requirements for the channel estimation at the receiver...
This paper investigates the performance of the downlink in Multi Carrier CDMA (MC-CDMA) systems using a channel model from in-the-field propagation measurements. Results are presented also for channel models having non-exponentially decaying profiles. Channel coherence bandwidth (Bc) is incorporated within the analysis in order to demonstrate the effect of channel frequency selectivity on system performance...
There are two basic duplexing schemes for present and future mobile radio networks, frequency-division duplex (FDD) and time-division duplex (TDD). In general each of these methods has its benefits and drawbacks. However, both schemes have their scenarios where they perform best. In future mobile radio systems typical wireless data communication will not only occur in metropolitan area scenarios like...
Cluster-based architectures are one of the most practical solutions in order to cope with the requirements of large-scale WSNs. In this work a new cluster-based architecture for sparse WSNs is introduced, the key issue of the solution presented is the multihop approach that is followed both in the communication from sensors to cluster-heads and from cluster-heads to the sink. Intercluster multihop...
The EU FP6 ANGEL project considers the usage of IEEE 802.15.4-based wireless sensor network technology in medical applications. Some key requirements found in this class of applications are not well supported by IEEE 802.15.4. In this paper we propose a wrapper layer on top of IEEE 802.15.4 that adds, amongst others, a mechanism combining priority queueing and per-packet parameter control to provide...
60 GHz wireless networks have the potential to support high data rate applications, but have short range transmission limitations due to larger propagation losses and reduced diffraction around obstacles. On the other hand, directional antennas are easier to implement at millimeter wavelengths and can provide benefits such as spatial reuse and higher transmission range. This paper proposes a network...
Enhanced Uplink operation of WCDMA-UMTS systems utilizes fast Node B scheduling and a short Transmission Time Interval (TTI) of 2ms. The scheduling decisions are based on scheduling information (SI) sent by each UE to the Node B. The main drawback of the current scheduling procedure is that the SI does not include any information regarding the delay sensitivity of each traffic flow, as well as the...
Digital video broadcasting for handheld terminals (DVB-H) is assuming an aver growing importance for digital video transmission over wireless terminals In this context, services are transmitted in ldquopacketsrdquo or ldquoburstsrdquo periodically repeating in time and interspaced by ldquooff-timerdquo periods. To improve this time sliced transmission effectiveness, a novel technique, the variable...
In this paper, we propose a scalable speech/audio coder control algorithm to improve quality of service (QoS) of voice over IP (VoIP) calls over wireless local area networks (WLANs). There is an upper bound on the number of simultaneous VoIP calls that can be connected in a basic service set (BSS) of 802.11 WLANs which can be composed of an access point (AP) and wireless stations (WSTAs). In the case...
This paper provides an overview of the methodology used in the performance assessment of the 64QAM and MIMO HSDPA features in a macro-cellular environment. The paper describes how the geometry experienced by end users could be measured in a live HSPA network, and how this could be used together with link level simulations to perform a first assessment of performance expectation of both MIMO and 64QAM.
This paper presents a methodology to estimate traffic load parameters in WLAN network consisting of a large number of access points (APs). The methodology takes into account the high variability of data traffic throughout the network that APs have to handle and process. It is based on using a low number of initial data formed from known statistical data about behavior of the network. The methodology...
OFDM (orthogonal frequency division multiplex) achieves high spectral efficiency in broadband wireless communications but has poor amplification efficiency due to its large peak-to-average power ratio. This paper presents achievable average power efficiency for the OFDM signal when the Doherty and extended Doherty transmitters are employed. By modelling the envelope of OFDM signal as a Rayleigh-distributed...
In this paper a mathematical model for the non-beacon enabled mode of the IEEE 802.15.4 Multiple access control (MAC) protocol, is provided. A wireless sensor network (WSN) composed of nodes which transmit data to a sink through direct links, is considered. Upon reception of a query from the sink, the nodes transmit their packets by using the carrier sensing multiple access with collision avoidance...
This paper addresses a method to mitigate the peak to mean power ratio (PMEPR) of orthogonal frequency division multiplexing (OFDM) signals. The idea is to use adjacent bands of the OFDM spectrum to allocate optimized subcarriers so as to decrease the signal PMEPR with the help of SOCP optimization process. This way of doing has only sense if additional subcarriers all fall under the standard spectrum...
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