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In a two-way wireless relay network, two nodes communicate with each other through a relay, and throughput is enhanced by the relay transmitting a linear combination of the messages received from the two sources either at the bit level (digital network coding) or the signal level (analog network coding). In this paper, we solve for the fraction of time resources allocated to each transmission mode...
The IEEE 802.11 standard based Wireless Local Area Networks (WLANs) are widely deployed and have gained greater popularity. It is anticipated that WLAN will play an important rule in the future wireless communication systems in order to provide several gigabits data rate. However, it has been a challenging problem to support the IEEE 802.11 WLAN devices to fully exploit the high throughput gains offered...
Recently the Effective Capacity of multi-user wireless scheduling has been analyzed based on large deviation principle. The users' queue length distribution bound of wireless scheduling algorithm such as round robin and rate maximum was discussed based on Effective Capacity analysis. But for Queue Length Based (QLB) Rate Maximum scheduling algorithm, the analysis result is only limited to system bound...
We propose a new transmission protocol for two-hop transmission employing rateless coding in the first hop and rateless-network coding in the second hop. In this protocol, communicating pairs (CP) and also relays are partitioned into small clusters; afterwards, each CP-cluster is assigned one relay cluster to improve data transmission. This scheme increases the diversity order (in comparison to the...
As a conventional MAC control protocol for wireless networks, IEEE 802.11 DCF hasn't taken account into the requirement, which TCP/UDP hybrid stream access needs for MAC frame length. The TCP/UDP hybrid stream's transmission delay would increase significantly, that always generate failure of TCP stream transmitting. This paper proposes an improved IEEE 802.11 DCF protocol and theory model based on...
IEEE 802.15.4 is a standard of Low-Rate Wireless Personal Area Network (LR-WPAN), which provides the communications in short distance, low data rate, low power consumption. In IEEE 802.15.4 a guaranteed time slot (GTS) structure is defined to support high quality of service (QoS) to time-critical traffic. However, the transmission bandwidth of GTS may be wasted because of the inefficient allocation...
In this paper, we address the energy-efficient contact discovery issue in Pocket Switched Networks (PSNs), in which the nodes' mobility pattern shows strong social property. In a PSN, although the end-to-end connection may be disconnected most of the time for a given source-destination pair, several nodes periodically gather at certain hot spots and form well connected clusters. Based on such mobility...
A new quality of service (QoS) enhancement scheme for IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol is developed. It uses a combination of an adaptive access category (AC) traffic allocation, incorporated into the network's wireless side, and weighted round robin (WRR) queuing scheduling mechanism, incorporated into the wired side of the network. The adaptive traffic allocation...
We present an analytical model for a random resource allocation and scheduling scheme for non-real-time polling service (nrtPS) traffic in IEEE 802.16e network. We adopt two system assumptions; unsaturation condition for the queue of each mobile station, and random amount of resources in a frame for each nrt-PS traffic, which are realistic for practical network systems. By jointly considering the...
Nowadays, online social networking services are very popular. In this paper, we conduct a comparative study of two push schemes in online social networking services: timer-based push scheme (TPS) and push N scheme (PNS). Simulation results demonstrate that TPS has comparable performance to PNS and TPS is more friendly to implementations.
In this paper, the first results to show the power, bandwidth and RMS delay spread of an intra-vehicle optical wireless communication system from a passenger perspective are presented. This work builds upon a previous investigation of ours which had demonstrated potential for optical wireless deployment within a vehicle as a potential competitor to RF based systems. By now incorporating the presence...
In this paper, we introduce a novel fast angle and power adaptation method in optical wireless (OW) systems. The fast angle and power adaptive line strip multibeam system (FAPA-LSMS) can identify the optimum spots distribution based on a divide and conquer (D&C) algorithm and can achieve a signal-to-noise ratio (SNR) performance comparable to that obtained using the normal APA-LSMS. This results...
Wireless Mesh Network (WMN) have been envisioned as an important solution to the next generation wireless networking which can be used in wireless community networks, wireless enterprise networks, transportation systems, home networking and last-mile wireless internet access. Many proprietary mesh solutions were developed by individual vendor but in order to interoperability; IEEE forms a task group...
This paper reports on the quality of service (QoS) mapping mechanisms for converged OFDMA-PON and LTE networks to satisfy the stringent QoS requirements. Various options for exhibiting QoS mapping between the LTE bearers and optical OFDMA-PON queues have been presented. These include, wireless classes forwarded directly to one priority optical queue (so called non-mapping mechanism), 1:1 mapping where...
With the development of wireless sensor networks in industry, it is difficult for MAC protocol with single channel to meet the demands of combating interference, high reliability and low delay. The multichannel MAC protocol is a promising approach to meet these challenges. IEEE 802.15.4 standard is the foundation of ZigBee, WirelessHART and ISA100. This article proposes a multi-channel MAC protocol...
Being reliable and real-time, are the two most challenging requirements of wireless industrial networks due to the shared, error-prone and non-deterministic behaviour of wireless communication medium. Retry-Limit (RL) parameter of IEEE 802.11 standard directly effects on the packet reliability, whereas other parameters mostly effect on packet delay. In this paper, at first the delay-reliability trade-off...
This study investigates a Wi-Fi-based Wireless Networked Control System. This system is first modified in order to enhance resistance to interference. Then, it is subjected to different types of interference. The system consists of a workcell containing 30 sensors, 30 actuators and 1 controller. All forms of interference modeled focus on the operating frequency band used by the control nodes. All...
The impulse ultra-wideband (UWB) channels covering the frequency range from 2 to 10 GHz, it covers indoor residential, door office, outdoor, industrial, and open outdoor environments. UWB communications systems share the spectrum with other systems in an unlicensed manner. This has caused a strict spectral constraint. In order to discuss power spectrum distribution, it analyzed the channel modeling...
In this paper, we propose a novel cellular optical wireless communications (COWC) system with four diffused cells. A dynamic handover scheme is proposed to make the link more flexible by the way of adaptive channel allocation in different environments. The simulation results show that the proposed algorithm offers almost five times of the maximum dynamic transmission bandwidth and energy efficiency...
Multipath routing has been proved effective in mobile ad-hoc networks (MANETs) for coping with link failures resulting from node mobility. In wireless mesh networks (WMNs) where routers are generally static, the traffic carried by the backup paths may adversely impact other flows and the multicast group itself, because these paths increase the number of transmissions and thus the level of interference...
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