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Main goal of this work is to give insight on the possible performance improvement arising in the wireless local ad-hoc access from the synergic cooperation of two emerging paradigms, multi-antenna and cognitive radios. The target is the competitive maximization of each access rate in presence of multiple-access interference (MAI) induced by the other accessing terminals. Being the radios cognitive,...
In this paper, we report on a mobile broadband wireless access(MBWA) system field trial with fast low-latency access with seamless handoff orthogonal frequency division multiplexing (FLASH-OFDM), which was carried out at Sendai city in Japan. This paper focuses on coverage and downlink throughput performance, which are the most important criteria for assessing wireless data communication systems....
Passenger counting is an important task for intelligent public transportation system??s planning and operation. However, traditional counting systems can??t identify individual passengers. The access to this additional capacity would allow collecting historical statistics on each passenger??s transportation needs, hence enabling a substantially enhanced optimization in these systems. With this purpose,...
We propose a new technique to estimate the signal-to-noise ratio (SNR) over flat fading time-varying single-input multiple-output (SIMO) channels, for quadrature amplitude modulation (QAM) signals in complex additive white Gaussian noise (AWGN). This technique relies on the use of periodically transmitted pilot symbols in the estimation process. It is a decision directed (DD) procedure since detected...
The typical radiating power levels of the DVB-H sites are normally between the values used in mobile and television broadcast networks. It is thus important to take into account accordingly the EMC (Electro Magnetic Compatibility) as well as the human exposure limits in the DVB-H transmission facilities. This paper presents a practical method for estimating the safety limits of human exposure and...
Performance of cooperative spatial multiplexing systems over composite channels is presented. In particular, we derive the closed-form average symbol error rate (SER) expression for cooperative spatial multiplexing systems with linear equalization receiver (e.g. Zero-Forcing) and M-ary modulation scheme in the composite channel of log-normal shadowing and Rayleigh fading. Using the Gauss-Hermite quadrature...
Multiple antennas are known to increase the link throughput by providing a multiplexing gain which scales with the number of antennas. Especially in cellular systems, multiple antennas can be exploited to achieve higher rates without the need for additional base station (BS) sites. In this direction, this paper investigates the multi-antenna capacity scaling in a cellular system which employs multicell...
In this paper, we introduce further our recently designed family of L2 orthogonal space-time codes for CPM. With their advantage of maintaining both the constant envelope properties of CPM, the diversity of Space-Time codes and moreover orthogonality, and thus reduced decoding complexity, these codes are also full rate, even for more than two transmitting antennas. The issue of power efficiency for...
The purpose of the present paper is to investigate the MIMO performance of the L-band multi-port Eleven antenna. Both a single- and dual-polarized lab model are investigated, both having 4 ports per polarization. The 4 ports per polarization are normally combined in a 180 deg hybrid to produce sum and difference patterns, but we investigate them here as individual ports in an antenna for a MIMO system...
Standardization work is nearly complete on long term evolution (LTE) of the UMTS Terrestrial Radio Access and Radio Access Network which is aimed for commercial deployment in 2010. Goals for the evolved system include support for improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration...
Cognitive radio (CR) is currently being seen as the future for wireless communications. Fundamental to the operation of a CR is the detection of presence of legacy communication. Energy detector (ED) is a simple and effective signal sensing method. However, the ED requires accurate estimation of the noise power. Any error in the estimation, which is common in practice, affects its performance. In...
In order to detect the presence of the primary user signal, spectrum sensing is a fundamental requirement to achieve the goal of cognitive radio (CR). This ensures the efficient utilization of the spectrum. Cyclostationary detection is the preferred technique to detect the primary users receiving data within the communication range of a CR user at very low SNR. In this work, we investigate the performance...
In this paper, we investigate the performance of using high altitude platforms (HAPs) for low power wireless sensor network (WSN) applications. In our study, HAPs are employed to replace the sink usually deployed on the ground and collect data from sensor nodes. Two scenarios of employing the HAP as the sink in the WSN are established. Multiple sensor nodes are organized in an ad-hoc manner or in...
In wireless ad-hoc networks, where nodes are often equipped with batteries, energy is a scarce resource. Therefore, power consumption of network operations is critical and subject to optimization. One of the fundamental problems in ad-hoc networks is multicasting. In this work we consider the so-called minimum energy multicast (MEM) problem, which can be stated as a combinatorial optimization problem...
Antenna tilt is an effective inter-cell interference reduction technique which has been studied a lot previously in the CDMA-based systems. In this paper, we concentrate on the evaluations of the mechanical antenna downtilt in the uplink LTE networks. The SINR performance and the trade-off between the cell coverage and capacity are studied in a homogeneous scenario. Simulation results in Macro 1 show,...
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