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Fiber Wireless (FiWi) provides a solution that combines gigabit passive optical network and Wi-Fi to provide huge capacity as well as mobility support. To manage the bandwidth in FiWi, a dynamic bandwidth allocation is proposed in this paper where it uses time division multiple access at the optical part and Carrier Sense Multiple Access with Collision Avoidance at the wireless part. Two methods are...
This paper presents the adaptive logarithmic increase and adaptive decrease algorithm, called A-LIAD, as an alternative for the current TCP congestion control algorithm. We defined new increasing function in the fashion of logarithm depending on the increasing factor α which is different from the other logarithmic increase algorithm adopting the fixed vale of α = 2 leading to binary increase. The...
A geometric model that describes a multipath propagation for a fixed wireless communication system between a high altitude platform and a fixed terrestrial user is presented. The model describes the propagation of the reflected signals that are able to reach the receiver as a consequence of all the scatterers located inside the system coverage area. The establishment of a particular geometry characterizing...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
The multi-access scheme of 802.11 wireless networks imposes difficulties in achieving predictable service quality in multi-hop networks. In such networks, the residual capacity of wireless links should be estimated for resource allocation services such as flow admission control. In this paper, we propose an accurate and non-intrusive method to estimate the residual bandwidth of an 802.11 link. Inputs...
A new super-resolution algorithm for time delay estimation (TDE) of multipath propagation signals base on least square criterion was proposed. The idea was to decompose the observed data into their signal components and then to estimate the amplitude and time delay of each signal components separately, using cubic slpline interpolation and basing on least square criterion. The algorithm iterated back...
A scheme that exploits the broadcast nature of the wireless communication in order to achieve multicast content delivery is presented in this paper. As opposed to broadcasting, this method enables the clients to determine on-line the delivered content, and thus preserves the advantages of an individual service. On the other hand, a multicast content delivery is much more efficient than a unicast content...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H), which is required to operate under high mobility conditions resulting in significant Inter-carrier Interference (ICI). To mitigate ICI, several cancellation schemes have been proposed but they require reliable channel information at the receiver which is quite challenging...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H) which is required to operate under high mobility conditions resulting in significant Inter-Carrier Interference (ICI). Under these conditions, the conventional one-tap per subcarrier channel estimation and equalization is suboptimal since it does not account for ICI...
In this paper, we introduce a pricing model that ensures efficient resource allocation that provides guaranteed quality of service while maximizing profit in multiservice networks. Specifically, a dynamic allocation policy is examined that relies on online measurements while each service class operates under a probabilistic bound delay constraint. We present a rigorous analysis of the properties of...
In this paper, we study bandwidth management of a wireless/optical based access/metro network in support of voice and data services. For voice services, we use a finite state Markov Chain to estimate the blocking probability of voice circuits over an Adaptive modulation and coding wireless channel, as a function of the channel parameters. For data services, we evaluate a rate matching and a buffer...
The next generation of wireless networks (4G) will use OFDMA (Orthogonal Frequency Division Multiple Access) in the reverse link. In OFDMA, the reverse link resources assigned to a user are called tiles each of which consists of a subset of consecutive subcarriers. Since at most one user is assigned to each of these tiles then reverse link transmissions within a sector are orthogonal. However, the...
Correlative minimum shift keying (MSK), a second order polynomial modulation scheme known as tamed frequency modulation (TFM), is a constant envelope type of modulation with a perfect peak to average power ratio (PAPR), besides the property of low out of band power. We apply the linearized TFM to the single carrier transmission with frequency domain equalization (SC/FDE) concept. We then obtain a...
This paper investigates the effective gain of antennas in indoor channels. A metric called instantaneous effective gain is proposed, and a multiple-cluster 3D channel model is used to facilitate the proposed antenna effective gain. In the multiple-cluster channel model, Laplacian and double exponential distribution are utilized to model azimuth and elevation signal power distribution respectively,...
Fast Fourier Transform (FFT) is the most basic and essential part of Software Defined Radio (SDR). Therefore, designing regular, reconfigurable, modular and low hardware complexity FFT computation block is very important. A single FFT block should be configurable for varying length FFT computation and also for computation of different transforms like DCT, DST etc. In this paper, the authors analyze...
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