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Next generation of wireless broadband network such as WiMAX MMR networks and LTE Advanced support high quality multimedia services with high data transmission rate. Most of the current broadband operates at high frequency and thus has limited transmission range. Multi-hop relaying technology is seen as an efficient solution that could enhance coverage and improves system capacity. However, overall...
In this paper, we present a low-complexity decoder architecture for WiMAX low-density parity-check (LDPC) codes based on a unified task processor. Memory access is accomplished through routing networks with fixed interconnections and memory address generators, which are quite simple due to the quasi-cyclic structure of the LDPC codes. In order to increase the decoding throughput, the check-node and...
Almost all deployed implementations of the IEEE802.16 standard (also known as WiMAX) employ the Point to Multipoint (PMP) topology. With such a topology Quality of Service (QoS) can be easily achieved, but the coverage area is limited. The other architectural topology is the Mesh Mode which is able to provide a larger coverage area, but cannot support the QoS required. This paper addresses the issue...
This paper demonstrates the usage of novel cognitive methods that improve the throughput of a WIMAX network by minimizing packet loss. The effects of the ant colony and fastest path routing algorithms on the throughput are investigated. a combination of Time Division Multiple Access (TDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) spectrum sharing techniques is used. Data packet loss...
In the paper we investigate the methods of constructing the routing tree in WiMAX networks with mesh topology. The concept of network efficiency optimization by building the routing tree characterized by selected topological properties that are independent on network load is presented. As an important partial result, correlations between topological parameters of the tree and network efficiency have...
System capacity is an important factor that affects the performance of WiMAX system where the amount of data that can be delivered to the end user is determined based on the system capacity and users QoS requirements. This scenario is even more complex when multi-hop relays are introduced into the network whereas the user access capacity decreases with the increase of hop number. In order to maintain...
This paper studies the joint OFDMA resource allocation and QoS routing problem in a hybrid wireless network, which includes an OFDMA based cellular network and an ad-hoc network with many sensor nodes. In such application, each sensor node generates certain amount of data that need to be sent to cellular base station (BS). The cellular nodes act as gateway to forward all the uplink traffic. We formulate...
In this paper, we introduce cognitive wireless network for a disaster information system based on dynamic network reconfiguration method to improve the connectivity. Our network system is consisted of multiple mobile routers based on currently available wireless LANs including IEEE802.11b, g, j, n, IEEE802.16 (WiMAX), cellular networks. Using those different standardized wireless networks, the disaster...
To use WLAN (wireless LAN) terminals anywhere, mobile wireless routers (MWRs) that can connect WLAN terminals to the backbone network by using WLAN-WiMAX (Worldwide Interoperability for Microwave Access) relay are receiving a lot of attention. These MWRs have small chassises because of their mobility. Therefore, the WLAN device and WiMAX device are adjacent to each other in these MWRs. Moreover, the...
The amendment of 802.16e has been released lately by IEEE 802.16 Relay Task Group j. For the sake of improving throughput and extension of cell coverage, relay stations (RSs) are deployed in the network. Intuitively, the base station (BS) selects a path for a target subscriber station (SS) according to Signal to Interference plus Noise Ratio (SINR) or the available bandwidth. However, it will lead...
WiMax mesh network provides a mechanism for creating multi-hop mesh, which can be deployed as high speed wide area wireless network. The routing and scheduling are two key factors that influence the performance of the WiMax mesh networks. In this paper, we introduce cross-layer design scheme and take both routing and scheduling into account in order to improve the performance. A centralized scheduling...
Future wireless communication systems are expected to provide more stable and higher data rate transmissions in the whole network. WiMAX is one of the technologies to cover diverse geographic regions. WiMAX covers the high dense urban areas and provide access over large geographic regions in remote rural area. However, in both scenarios it is challenging to cover the entire service area. In both cases...
As advanced integrated network architecture, ldquocognitive radio technologies,rdquo which aim to improve the spectrum efficiency, have been studied. In the cognitive radio networks, each node recognizes radio conditions, and according to them, optimizes their wireless communication routes with the integration of the heterogeneous wireless systems not only by switching over them but also aggregating...
So far we have developed a disaster information network which is very effective and robust using wireless network. In this paper, we introduce a mobile network for disaster communication network by combination of different wireless LANs and mobile network. Currently available wireless LANs such as IEEE802.11b,g,j,n, IEEE802.16 (WiMAX), cellular network are combined with a mobile router and loaded...
The diversification of wireless communication usage has been proceeding rapidly with the diffusion of cellular phones, WiFi and WiMAX. In the emerging wireless communication environments, diverse wireless systems coexist. On the other hand, there is increasing concern that the growing use of wireless systems will exhaust the finite wireless resources. To solve this problem, we aim to optimize the...
In emerging wireless relay networks (WRNs) such as IEEE 802.16j, efficient resource allocation is becoming a substantial issue for throughput optimization. In this paper, we propose an algorithm for joint routing and link scheduling in WRNs. The developed theoretical analysis indicates that the performance of the proposed algorithm is within a factor of three of that of any optimal algorithm in the...
As advanced integrated network architecture, "cognitive radio technologies," which aim to improve the spectrum efficiency, have been studied. In the cognitive radio networks, each node recognizes radio conditions, and according to them, optimizes their wireless communication routes with the integration of the heterogeneous wireless media not only by switching over them but also aggregating...
WiBro (Mobile WiMAX) is a broadband wireless internet service supporting for fixed, portable and mobile users, but enhancement of service quality in indoor environment is still necessary. WiBro femtocell is developed to expand cell coverage, increase system capacity and offer various multimedia service with high throughput in indoor environment. Three types of femtocell are designed according to the...
WiMax/802.16 mesh network is an emerging infrastructure that offers a cost-effective deployment for highspeed wireless broadband access to the back haul network. However, as in most wireless multi-hop networks, WiMax/802.16 mesh suffers from interference that decreases considerably the throughput and spatial reuse of the network. Interference in WiMax/802.16 mesh is a result of several phenomena,...
WiMAX mesh mode, recently standardized, enables direct communications between subscriber stations without referring to the base station (BS). It can be a great solution for providing access in hard-to-wire areas and especially in extending the coverage of the BS. In this paper, we propose a joint routing and scheduling algorithm for improving the performance of WiMAX mesh networks in terms of throughput...
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