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Joint beamforming with receive combining is a simple method for exploiting the significant diversity provided by multiple-input multiple-output (MIMO) systems, and the use of orthogonal frequency division multiplexing (OFDM) enables low complexity implementation of this scheme over frequency selective MIMO channels. In this paper we analyze the combination of MIMO systems with OFDM using joint beamforming...
This paper studies the performance of scheduling algorithms for High Speed Downlink Packet Access (HSDPA) over wireless channels. The throughput performance has been considered with the three scheduling algorithms: Round Robin, Maximum C/I, and Fair Channel Dependent Scheduling (FCDS). A simulation approach is adopted with two scenarios: File Downloading and Voice Streaming. The simulation results...
This paper presents an architectural solution for a MMSE equalizer of iterative receiver for linearly precoded MIMO systems. Two transmit antennas, two receive antennas, and a preceding size of two were chosen for the linearly precoded MIMO system. Thanks to the orthogonality property of Hadamard matrix that is used for the linear preceding and the block-fading nature of the MIMO channel, the inversion...
Personal optical wireless (POW) refers to use of free- space propagation of light for short range communications in an indoor context. POW offers several advantages over radio technologies, making it an attractive solution for home networks. Orthogonal modulations such as OFDM are currently used in many radio transmission standards. Among these modulations, OFDM/OQAM is an interesting alternative...
Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents an admission...
A server sharing model is presented to model the downlink scheduler in 3G wireless networks. This model is used to find the average achievable service rate per user for a given fairness criterion. The wireless channel is modeled by a Finite State Markov Channel (FSMC) to reflect the effect of Adaptive Modulation and Coding used in 3G wireless networks. This model can be used to implement differentiated...
In spite of the good benefits of using MIMO technology with modern wireless systems, a major problem has arisen from using it with small wireless terminals. When antennas are placed with less than half wavelength apart then mutual coupling occurs. Researchers have found that mutual coupling can affect the performance achieved by multiple antennas which results in a large reduction in channel capacity...
It is very critical to manage data in the wireless environment. Through the use of push technique, data may be retrieved by wireless users in an efficient manner. In this paper, I show a description of an architecture which is designed to provide a flexible access to data in a multi-channel dissemination- based network. I show how a suitable system fits in the overall telecommunication network. The...
In this paper, the ratio of signal to interference for underwater acoustic channels is calculated. Based on this ratio, upper bounds on the maximum permissible density of simultaneous transmissions of underwater sensor networks that allows a certain probability of successful reception, in two different models, are determined. In the first model, the distance between source and destination is assumed...
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