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In the next generation wireless systems, it's quite likely that a large number of user terminals are not able to transmit and/or receive over the entire system bandwidth, as much wider system bandwidth, e.g., 100 MHz, is expected to be employed in the future. As a new and challenging problem, user terminal bandwidth limitation is considered in this paper, and multiuser resource allocation for orthogonal...
In this paper, an interference alignment system for the distributed MIMO network is investigated. We propose a new precoding scheme using interference alignment in modulation signal domain. The simulation results show that the proposed one-dimensional precoding scheme can provide significant performance improvement over the conventional schemes using interference alignment.
In recent years, Worldwide Interoperability for Microwave Access (WiMAX) has become an important technology providing wireless connections for mobile terminals in a wireless Metropolitan Area Network (MAN), due to its large radio range. In a MAN environment, wireless clients always have high mobility; therefore, it is possible that the mobile clients will move away from the service coverage of serving...
Rings overlay is a class of multi-path routing structure for wireless sensor networks that exploits the broadcast nature of wireless communication to cope with communication failures. While the rings overlay aims to create multiple propagation paths for sensor nodes to transport data, the sensor nodes in the ring next to the base station inherently have only a single propagation path to the base station...
The femtocell base station is a low power and low cost small base station in the customer premise. It connects to the core network via cable, DSL or similar backhaul technology. In this paper, we focus on how received signal quality can be improved by deploying femtocell base stations in a WiMAX system. We propose a suburban femtocell model to analyze the potential improvement on the SINR when using...
One way of modelling the wireless channel is in a statistical manner, based on a few parameters describing the characteristics of the environment. In most current wireless channel models, these key parameters are assumed independent between separate links, i.e. on the channels modelling the propagation between one base station and several mobile stations, or one mobile station and several base stations...
This paper studies the problem of energy consumption minimization in wireless sensor networks (WSNs) under uncertainty in sensor node generated traffic. It is important to consider traffic uncertainty because WSNs designed for surveillance and monitoring applications typically operate in event-driven and query-driven modes for which the node generated traffic changes from instant to instant. The problem...
Coverage is an important problem in wireless networks. Together with the access probability, which measures how well an arbitrary user can access a wireless network, in particular VANET, they are often used as major indicators of the quality of the network. In this paper, we investigate the coverage and access probability of the vehicular networks with roadside infrastructure, i.e. base stations....
The problem of Compressed Sensing (CS) based multiple access is studied under the assumption of random data traffic. In many multiple access systems, e.g. Wireless Sensor Networks (WSNs), data arrival is random due to the bursty data traffic for every transmitter. Following the recently developed Compressive Sensing methodology, the technique of compressing the transmitter identities into data transmissions...
This paper presents a simple solution suitable for the mandatory localization function for E-911 services specified by FCC. Our solution introduces zero-length spring technique to compute the estimated location based on received signal strength (RSS). The introduced zero-length spring concept permits a less detailed path loss model to use without significant impact to the location estimation. We show...
In this paper, we develop new energy-efficient, radio resource management schemes for green wireless networks. Our goal is to optimize energy consumption at the network scale while preserving the Quality of Service (QoS) perceived by users. We specifically propose two new sleep mechanisms for base station where a number of resources in system can be shut down for some traffic scenarios in one of two...
Wireless sensor nodes typically have limited processing capabilities and are powered by batteries. The amount of energy expended in transmitting a single data bit would be several orders of magnitude higher when compared to the energy needed for a 32 bit computation. Thus, to maximize network lifetime, data transmissions should be minimized without losing vital information. In this paper, a novel...
It is well known that symbol timing offsets larger than the cyclic prefix as well as carrier frequency offsets between transmitter and receiver stations destroy the orthogonality among OFDM subcarriers and induce additional interference. In conjunction with MIMO transmission on frequency selective fading channels where different users interfere with each other, these effects strongly degrades the...
Orthogonal frequency-division multiple access (OFDMA) exploits the frequency selective property of a wireless communication channel by allocating subchannels to individual users. Conventional multicast systems, however, suffer from diversified channel conditions among users. The main contribution of this paper is to maximize the multicast rate of one multicast session while being fair among users...
Base station cooperation is considered as a promising approach to increase the quality of service (QoS) in uplink. Base stations are connected via high-capacity backhaul links, which makes it possible to perform joint detection through information sharing among several base stations. Joint detection broadens the feasible signal to interference ratio (SIR) region, in which any SIR assignment for all...
This paper considers a wireless sensor network with Time-Hopping-Impulse-Radio Ultra Wide Band as the physical layer. The network is structured as a group of interconnected cells that are not synchronized with each other. In such an unsynchronized environment, inter-cell interference is not Gaussian, but generalized Gaussian. For such a non-Gaussian random interference, its impulsiveness is determined...
Seamless handoff between different wireless technologies is a vital requirement for the next generation mobile networks (NGMN). The soft handoff (SHO) method provides seamless roaming, but makes heavy use of battery and radio resources. In this paper, we propose a conservative soft handoff (cSHO) which maintains the benefits of SHO and reduces the consumption of resources. Instead of using both radio...
We propose a simple linear precoding scheme to cancel interference in downlink multiuser cellular relay networks where the available information is asymmetric between the base station and the relay node. The interference signal from the relay is eliminated by linear pre-pocessing at the base station without any cooperation between the base station and the relay. In the information asymmetric environment,...
Future cellular systems such as LTE-Advanced systems offer improved coverage, system throughput, and cell-edge throughput through the effective use of coordinated multi-point processing (CoMP). In this paper, we propose cooperative multicell automatic repeat request (ARQ), which exploits both the cooperation among base stations via backhaul links and ARQ. First, it involves minimal change in the physical-layer...
In this paper, we investigate the construction of rings overlay in wireless sensor networks for enhancing the robustness of sensor data collection. Rings overlay is a class of multi-path routing structure that exploits the broadcast nature of wireless communication to cope with communication failures. We propose a distributed approach for constructing the rings overlay to allow sensor nodes to benefit...
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