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Almost all modern cars can be controlled remotely using a personal communicator (keyfob). However, the degree of interaction between currently available personal communicators and cars is very limited. The communication link is unidirectional and the communication range is limited to a few dozen meters. However, there are many interesting applications that could be supported if a keyfob would be able...
With the development of recent vehicular communication technologies, distributing multimedia contents in the vehicular communication networks (VCNs) has become more and more popular, to provide conveniences and entertainment services during the time of driving. However, as multimedia contents are changed and updated dynamically, how to keep the consistency between the original and these replicas in...
The latest generation of wireless networks use OFDMA (Orthogonal Frequency Division Multiple Access) transmission technology in the downlink (e.g, WiMAX and LTE). The downlink is divided into bandwidth units and UEs (User Equipments) are each allocated a subset of these. Since at most one UE is assigned to each of these units, downlink transmissions within a sector are orthogonal. However, the transmission...
This paper proposes a new 4-dimensional(4D) constellation-rotation(CR) method which obtains diversity gain of 4 under Rayleigh fading channels. The proposed scheme uses two consecutive CR operations for the constellation of QAM signals unlike a conventional 2-dimensional(2D) CR method using only one CR operation. The computer simulation results show that the new method outperforms the conventional...
Multiuser diversity is achieved by maximum C/I scheduler in both fast and slow fading scenarios. However, fairness among multiple users is not guaranteed in slow fading channel because time and frequency resource are always occupied by the user with largest signal to interference and noise ratio(SINR). Opportunistic beamforming using dumb antennas is a multiple antennas transmit technique to increase...
Smart antennas have received increasing interest due to its capability for improving the performance of wireless radio systems. In this work we studied the throughput maximization in a CDMA 1xEV-DO cellular system when a smart antenna array is implemented. We focus in the downlink of the CDMA cellular system and consider a packet data direct-sequence code division multiple access (DS-CDMA). We show...
WANETs is a recent network architecture where the nodes are spread all over the world but behave exactly as if they are part of a single-hop or multi-hop wireless networks at the PHY and MAC layers. Without distinguishing data packets and noise, the Software Defined Access Point (SoDA) samples the wireless channel for the uplink and multicasts the sampled data via Internet to other SoDAs. This leads...
Implementing idle mode for the mobile station (MS) in a mobile communication system results in two kinds of control overhead: paging message overhead and location update overhead. In this paper, we propose a mobility-based paging mechanism which utilizes the MS's mobility information to reduce the number of unnecessary broadcast paging messages. To further reduce the paging message overhead, instead...
The indoor femtocell technology (known as femto BSs) with low power and low cost is proposed to provide comprehensive indoor wireless converge of macro BSs, which is known as the femtocell network. The Location Area ID for a femtocell is different from that for the macrocell that covers the femtocell, which results in frequent location update procedure (i.e., the location update cost increases) when...
Wireless equipped machines are increasing greatly in recent years, among which the cellular network based machine-to-machine communication (M2M) has shown the advantages of better coverage and lower network deployment cost. However, the current cellular network is designed for human-to-human communication, targeting the voice/media transmission with low access delay and high throughput, so the machines...
In this paper we propose a multiuser receiver using multistage detection and interference cancellation for direct-sequence code-division multiple-access (DS/CDMA) systems with parity bit selected spreading sequences in synchronous channels. In a CDMA system with parity bit selected spreading sequences (CDMA/PB), the spreading code used by each user depends on the transmitted data bits and it is selected...
In this paper, the performance of beamforming in two-hop relay networks with Rayleigh-Rician asymmetric fading channels is investigated. This network consists of a relay node equipped with a single antenna, a source and a destination node both equipped with multiple antennas. The first and the second hop are respectively subjected to Rayleigh and Rician fading. Transmit beamforming and receive beamforming...
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