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Zadoff-Chu (ZC) sequence has been proposed as the contention based ranging preamble code (RPC) in 3GPP LTE and IEEE 802.16m specifications. The performance of the initial ranging process is affected by the number of available RPCs. In scenarios with high mobility and large round-trip delay (RTD), however, the number of available RPCs is limited; this would result in a higher collision probability...
In this paper we consider an IEEE 802.15.4-based Wireless Body Area Network, where wearable sensor devices are distributed on a body and have to send the measured data to a coordinator. The Carrier Sense Multiple Access with Collision Avoidance algorithm defined by the standard is used as Medium Access Control protocol, whereas different modulation schemes are assumed to be available at the physical...
The network throughput will decrease dramatically and collision rate increases severely when active nodes increase in WLAN. Breaking through the limitation of the Binary Exponential Backoff algorithms, we provide a new backoff algorithm which utilizes the linear contention window based on the node numbers. To attain better performance, we derive that the contention window is selected as an approximate...
Due to the complexity and time-variation of wireless channel, it is a great challenge to measure and estimate the channel quality accurately in wireless ad hoc network. To address this problem, we propose a link quality estimator which use the packet loss rate (PLR), round trip time (RTT), available bandwidth (ABW) at the sender and the feedback information from receiver to continuously tracks the...
The Gulf of Finland (GOF) is considered one of the most dense place in the world in terms of marine traffic, and in addition to the Danish Straits it forms the narrowest and shallowest waters in the Baltic Sea. As the volume of shipping in the GOF increases constantly, so does the risk of accidents. This paper presents a model for risk assessment for vessels colliding with emphasis put on tankers...
Radiofrequency identification has emerged a lot of applications where object identification is necessary. This technology seems to be, unlike traditional object identification, the optimal solution to achieve a contactless transfer of information between a reader (interrogator) and tags. Where the reader attempts to identify more than one tag in its interrogation area, this situation may lead to a...
Tag identification time is handled as an important factor because the performance of RFID system is decided by this factor dominantly. To improve this ability, many anti-collision algorithms have been applied on RFID system. ALOHA based anti-collision algorithms are simple and they have superior anti-collision ability. But, it has disadvantage that the identification performance grows worse as the...
Bluetooth is a digital data transmission standard in the 2.4-GHz ISM band that uses short-range wireless links between devices. As this band is free and it is used for other several wireless technologies such as IEEE 802.11b, Bluetooth uses a frequency hopping method to minimize interferences. The main goals of this paper are to provide a statistical characterization to describe the packet collision...
Collision-based hopping multiplexing was previously proposed with names of orthogonal code hopping multiplexing (OCHM) and orthogonal frequency hopping multiplexing (OFHM). A major performance measure of these schemes is collision probability, which is closely related to block error rate performance in receiver. In this paper, we analyze the code-collision probability of OCHM in a multi-rate transmission...
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