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In this paper, a novel communication system is introduced, i.e., the frequency-hopping multiple-access OFDM-BPSK communication system. Based on characteristic function method, the bit error rate (BER) performance of the system is derived in additive white Gaussian noise (AWGN) and Rayleigh fading channels. The numerical results firstly indicate the relationship between BER and the parameters such...
This paper proposes a cross-layer based power-aware multipath routing protocol (CPMRP) for wireless mobile ad hoc networks. The nodes' mobility behavior is predicted using a notion of "signal fading degree, SFD". On the other hand, loop-freedom guarantee is provided by "signal identifier, SI". Especially, in combination of the IEEE802.11e standard at the MAC layer, we determine...
We present results on the development of crosstalk cancellation techniques for OFDM systems. Using over-sampling and subspace principles, the crosstalk symbols and/or the null space of the crosstalk channel matrix are identified. Accordingly, two subspace-based crosstalk cancellation methods are proposed and their performances are evaluated through simulation.
To overcome the PAPR problem of conventional orthogonal frequency-division multiplexing (OFDM) system, a significant amount of methods have been proposed. However, there are few literatures considering the PAPR reduction for uplink orthogonal frequency division multiple access (OFDMA) system. In this paper, we focus on the PAPR reduction for random interleaved uplink OFDMA system. Firstly, the conventional...
In this paper, a construction method of quantum low density parity check codes (quantum LDPC) which based on classical quasi-cyclic sparse sequence is proposed, and the quantum code QLDPC(3,8)(16,6) and QLDPC(3,8)(64,24) are selected as examples to illustrate this construction method. The performances of this kind quantum LDPC codes are discussed over the bit-flipping channel by numerical simulations...
Connectivity maintenance plays a critical role in wireless sensor networks, while traditional communication range only considers direct transmission. In this paper, cooperation transmission is utilized in sensor networks, with the performance of cooperative communication range being analytical evaluated, in comparison with direct transmission. Cooperation is capable of enlarging a node's range to...
In this paper, an embedding construction of tail-biting trellises for linear block codes is presented. With the new approach of constructing tail-biting trellises, most of the study of tail-biting trellises can be converted into the study of conventional trellises. It is proved that any minimal tail-biting trellis can be constructed by the recursive process of embedding constructions from the well-known...
Network coding has generated much interest in information and coding theory, networking, wireless communications, cryptography, and computer science in the past few years. Consider a point-to-point communication network on which a number of information sources are mulitcast to certain sets of destination nodes. The problem is to characterize the maximum possible thruputs. Contrary to one's intuition,...
The grid would see the countless mobile devices becoming the most important users. However, the bottleneck is still at the last mile from the backbone to these mobile terminals where wireless environment places limitations on the rate and amount of communication. Currently, point-to-multipoint (PTM) communication is an effective solution to this limitation. This paper developed a new PTM mechanism...
For the minimization of RFID tag antenna, we designed a printed folded dipole antenna working at 2.4 GHz. And a mirror compensation technology was introduced to improve the radiation feature of antenna with better return loss characteristic and directivity. The simulated results show that when VSWR (vertical standing wave ratio) is less than 2, the antenna bandwidth is up to 0.39 GHz absolutely and...
The purpose of the IEEE 802.22 working group is to develop a standard for the wireless regional area network (WRAN) based on cognitive radio technology. Much research has been done in relation to the WRAN. Besides experience from understanding other communication systems and theoretical methods, simulations are essential to the design of a novel system. This paper presents the detailed structure and...
With remarkable advances in wireless communications and mobile devices, wireless community networks (WCNs) become more and more attractive. Plenty of applications have been developed. Among others, instant messaging (IM) can be used for real time communications in a community network. In a wireless community network, nodes may spontaneously join or leave from time to time. In this paper, to meet the...
Currently, it's a challenge to provide differentiated quality media services in Internet, especially under peer-to-peer (P2P) model. Most P2P based algorithms are not support the service scalability. In this paper, we propose an optimized algorithm, which integrate an excellent P2P algorithm SIM and scalable video coding (SVC) technology for media streaming (SPM). Hosts in SPM can specify media quality...
In this paper, we promote the use of online communities as a means to provide incentives for people to collaborate in building wireless community networks. To achieve this goal, we define a novel type of online community spanning a specific physical area (i.e., a neighborhood) called wireless neighborhood community (WNC). On the one hand, in addition to the standard activities of an online neighborhood...
This research explores the various solutions currently available for sharing Wi-Fi connections and seek to identify whether there are potential applications and business models that could be used to make such grass root and advertising-based deployments a viable alternative to the capital intensive wireless infrastructures offered by the dominant network integration players (e.g., Cisco, HP, IBM,...
This publication summarizes the results of four interview sets that were conducted during the years 2005, 2006 and 2007 to analyze an existing wireless city network - Sainet - and its potential. Sainet was opened to the public in 2002 and is being used to study open access networks with multiple service providers. The first interviews (2005) covered the consumer sector and analyzed user views on public...
Synchronization is important in order to correctly recover information for multi-antenna orthogonal frequency division multiplexing (OFDM) system. In this paper a novel transmitting diversity scheme named as maximal channel power (MaxCP) is proposed. Specifically the channel state information (CSI) is feedback to transmitter firstly and then only one of transmit antennas with the highest channel power...
Compared with P2P files sharing, media streaming has more stringent time and bandwidth requirements. Previous work indicates that finding a right peer to query for service will improve performance of a media streaming system. However, most of peer selection algorithms focused on how to choose an appropriate parent node to maximize the requesting peerpsilas profit, while ignoring improving overall...
Distributed denial of service (DDoS) attacks pose a major threat to today's cyber security. Defense against these attacks is complicated by source IP address spoofing. The Path Identification (Pi) mechanism is a promising technique to defend against DDoS attacks with IP spoofing. In the Pi scheme, each router marks forwarding packets to generate particular identifiers corresponding to different paths,...
Nilsimsa algorithm plays an important part in the anti-spam technique. In this paper, we introduce the concept of Nilsimsa vector based on the research on the procedure of the Nilsimsa digest generation. By taking the length of Nilsimsa vector as the key, we propose an approach to publish and perform lookup for Nilsimsa digest in Chord: PeerNil. We analyze the lookup efficiency and load balancing...
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