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Femtocells are low-power, very small-service-area (e.g. home or office environment) cellular base stations that will significantly impact the cellular landscape in the next several years. One of the most important open technical issues related to femtocells concerns the impact of femtocells on the performance of the conventional macro-cell system and the whole two-tier system, in this paper, a study...
Femtocells are a promising solution for the provision of high indoor coverage and capacity. Furthermore, OFDMA-based femtocells have proven to be highly versatile when dealing with cross-layer co-channel interference; however, concerns still exist related to the impact of the different access methods to femtocells in an overlaid network. Femtocells based on a Closed Subscribers group, where only device...
In this paper, we propose two novel methods for downlink preamble detection and initial coarse time synchronization for mobile WiMAX systems and other OFDM Systems that adopt similar preamble structures. The two methods are based on frequency domain processing. The two methods are compared to the conventional time domain method for frame detection in WiMAX and to another frequency domain algorithm...
The need for flexible network structures has created a successful Wireless Local Area Network (WLAN) market, promising to replace many wired LANs in the near future. The latest draft of IEEE 802.11n offers the potential of throughputs beyond 200 Mbps, based on physical layer data rates up to 600 Mbps. IEEE 802.11n standard adopts low density parity check coding as optional coding scheme to offer higher...
Recently, to meet higher data rate requirements, LDPC coded MIMO-OFDM systems are investigated widely. Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (OFDM) is an attractive solution for next-generation wireless local area networks (WLANs). Space-time block coded OFDM is capable of achieving substantial diversity gains, while...
This paper proposes new techniques for acquisition of hybrid DS-SFH spread-spectrum systems in the presence of partial-band interference in fading channels. The proposed techniques include differential detection followed by maximizing the circular cross correlation with a known PN sequence. This is extremely robust against tone interference. An interference rejection method is used to improve the...
High speed downlink packet access (HSDPA) is specified in the 3GPP to cope with the increasing demand of high-speed Internet-based multimedia services. This paper focuses on the throughput performance of wireless system on mobile internet services using HSDPA, and the affect of using multi codes and space time transmit diversity. Three packet scheduling algorithms are employed: carrier to interference...
In this paper, the reverse link performance of a power controlled wireless local loop (WLL) CDMA system equipped with high gain directional antennas at either the base station or users' houses is investigated. The link performance of mobile cellular CDMA system is studied. A comparative analysis of the capacity gain that is attained in Wireless Local Loop system over mobile cellular CDMA system has...
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