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Two novel numerically efficient approaches are proposed for maximum capacity designs in multiple-input multiple-output (MIMO) systems under the practical per-antenna power constraint. One is an explicit solution (ES) when the rank of the channel matrix is equal to the number of transmit antennas. And the other is an efficient iterative approach (EIA). The ES is optimum and the EIA is nearly optimum...
A new method has been developed to adjust volume automatically on all audio devices equipped with at least one microphone, including mobile phones, personal media players, headsets, and car radios, that might be used in noisy environments, such as crowds, cars, and outdoors. The method uses a patented set of algorithms, implemented on the chips in such devices, to preserve constant intelligibility...
Exploiting the broadcast nature of wireless channels, transmitted packets “skip ahead” to receiving nodes farther downstream along an existing, established mesh routing path. Packets are thereby able to more quickly advance through a mesh network towards their destination. This occurs on a packet-by-packet basis and is advantageous even if the underlying path (at that moment) has been optimized. Analysis...
In this paper we focus on the problem of code assignment to cognitive users in a synchronous underlay network using Code Division Multiple Access (CDMA) scheme. No knowledge of the spreading codes used by the primary CDMA network is available to the cooperative secondary users a priori, other than the spreading factor. An evolutionary algorithm of relatively low complexity order is proposed based...
In this paper we study the behavior of traffic in Metropolitan Access Optical Networks with technologies of optical packet/burst switching (OPS/OBS), using computer modeling and simulations. We analyze network performance and the impact of link failure when electronic buffering at ingress (client input) to optical network is implemented. Mesh and ring topologies are chosen and parameters packet loss...
Since different spatial streams in MIMO systems experience different SINRs, the soft bits of each spatial stream should be scaled according to its SINR. In this paper, we introduced the idea of soft demapping scaling according to SINR and proposed an improved scaling method using a constrained MMSE approach for OFDM MIMO systems. Based on IEEE 802.11n examples, good system performances are observed...
The uplink power control procedure in Long Term Evolution (LTE) cellular networks is made of an open-loop part and a closed loop part. In this paper, we focus on the former and study the compensation factor of the related Fractional Power Control (FPC) scheme. In particular, we propose a first analytical approach in order to derive approximate equations for the Signal to Interference plus Noise Ratio...
In this paper, two low-complexity belief propagation (BP) based detectors are proposed for multiple-input multiple-out (MIMO) system. The factor graph is leveraged to represent the MIMO channels, and based on which our algorithms are developed. Unlike the existing complicated standard BP detectors that consider all the edges when updating the messages, our algorithms only focus on single edge, which...
This paper presents node geometry and broadband jamming in noncooperative wireless relay networks under the received power constraint. Diagonal relay amplifying matrices based on minimum mean square error (MMSE) criteria corresponding to node geometry and broadband jamming in wireless networks under the received power constraint are derived. All relay nodes are assumed not to communicate with their...
In this paper we investigate the use of rateless codes by secondary users equipped with cognitive radio in a virtual unlicensed spectrum. Assuming a Poisson model for the arrival of primary users, we analyze the goodput and the throughput of secondary users. Rateless codes are used for transmitting the secondary data through parallel subchannels available in a spectrum. They can compensate for the...
This paper considers a Wireless Local Area Network consisting of Access Points that can provide only a limited cone of coverage. A dense access point deployment is required for such a network to provide coverage over a substantial area. Such a deployment introduces challenges associated with support of terminal mobility, backhaul management load and association. In this paper, we propose simple yet...
The design of a fully integrated balanced amplifier implemented in a 130 nm CMOS technology is described in this paper. This balanced amplifier achieves a gain of 30 dB from 19 GHz to 26 GHz. To reduce the signal loss and the physical dimensions of the 90° coupler utilized in this balanced amplifier, a meandered broadside coupler with shield is designed. This on-chip 90° coupler occupies a compact...
Directional networks provide significant promise for future high-bandwidth communications architectures. There is an increasing need for capacity to support multi-media and other bandwidth-intensive applications while spectrum availability is decreasing. Directional networks allow for high capacity communications by focusing the energy between transmitter and receiver and providing greater frequency...
Based on differential properties of the received preamble, a novel start of packet (SoP) detection and synchronization approach is developed for the IEEE802.11n MIMO-OFDM WLAN system to obtain better mean and variance of timing estimates and lower missing packet and false alarm rates.
Initial configuration and on-going optimizations of the Radio Access Network (RAN) are significant expenses for Wireless Service Providers (WSPs). Investments in skilled technicians and engineers as well as test tools are required to ensure a high-performance network. Self Organizing Networks (SONs) minimize the lifecycle cost of running a network — they make it more economical to deploy, operate...
More and more video application are being carried on wireless systems with the development of the smart phones. However, the performance of these applications is lack of study, especially for the most advanced LTE networks. In this paper, we investigate the performance of the video telephony over the LTE downlink systems with and without QoS provisioning. The simulation results using two classical...
The tagged user approach (TUA) is shown to be an effective method based on queueing theories to analyze random multiple access systems and avoid the high computational complexities of Markovian analysis. In this paper, we investigate using the TUA to analyze a finite-user finite-buffer slotted Aloha system considering AWGN and frequency selective fading effects respectively. The theoretical derivations...
We present a convergence analysis of a genetic algorithm based topological control mechanism for the decision making process of evolutionary and autonomous systems that adaptively reconfigures spatial configuration in mobile ad hoc networks (MANETs). Mobile nodes adjust their speed and direction using information collected from the local neighborhood environment in unknown geography. We extend the...
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