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The traditional vertical handover schemes postulate that vertical handover of each user comes on an individual basis. This enables the users to know previously the decision already made by other users, and then the choice will be made accordingly. However, in the case of a group vertical handover, almost all the VHO decisions — which will certainly choose the best network, will be made at the same...
In this paper, we investigate signaling overhead with heterogeneous bandwidth request (BR) for WiMAX multihop relay networks. The code division multiple access (CDMA) contention based BR suffers from high signaling overhead in WiMAX relay networks. Hence, we suggest heterogeneous bandwidth request in which the mobile stations (MSs) with relay connectivity exhibits message based BR and relay stations...
Internet services will be pervasive in future intelligent transportation systems. To this end, vehicular Wi-Fi networks are introduced and widely deployed nowadays. However, quantitative performance in vehicular Wi-Fi networks has not been reported in the literature. In this paper, we conduct a measurement study in vehicular Wi-Fi networks to investigate the uplink and downlink throughput under diverse...
The aim of this paper is to address one aspect of this challenge - how do we build affordable communication networks in developing regions by adapting technologies originally designed for the industrialized world to be appropriate and sustainable in the developing world environments It is in this context that the role of information and communication technologies (or ICTs) in development has been...
This contribution provides insight into the performance of the currently deployed 3G cellular systems HSDPA and WiMAX. In extensive measurement campaigns we measured the physical layer throughput of these 3G systems in different environments (alpine and urban) and compare the results rigorously to their upper bounds derived from the well known Shannon capacity. By separating the observed losses into...
Random access channel is incorporated in IEEE 802.16 WiMAX system to transport contention-based messages in the uplink, such as bandwidth requests generated by best effort applications, from mobile stations (MSs) to the base station(BS). Regarding the packet transmissions in the random access channel, delay, throughput and power consumption are usually considered as major performance metrics. We propose...
One of main challenges of fourth generation wireless networks (4G) will be the integration of various mobile technologies such as CDMA 1xEV-DO RA, UMTS/HSDPA and WiMAX. In this paper is investigated the interoperability between the CDMA 1xEV-DO RA and the UMTS/HSDPA in the 4G context. New algorithms for vertical handoff traffic acceptance are proposed considering the link occupation, the buffer occupation...
Random access channel is incorporated in IEEE 802.16 WiMAX system to transport contention-based messages in the uplink, such as bandwidth requests generated by best effort applications, from mobile stations (MSs) to the base station (BS). Regarding the packet transmissions in the random access channel, delay, throughput and power consumption are usually considered as major performance metrics. We...
Modern wireless communication systems employ MIMO and feedback-two properties that make it especially difficult to measure the performance of such systems with reasonable effort in actual outdoor scenarios. In this paper, we will present a time, cost, and manpower efficient measurement approach to evaluate the throughput achieved by such systems. Summer/winter, large distance outdoor-toindoor/outdoor,...
In recent years, smart antenna technologies are of ever-increasing interest to boost the capacity of existing and future wireless systems. Several standards support these techniques such as the wireless metropolitan area network IEEE 802.16 (WiMAX) and IMT-Advanced candidates. In applying smart antenna beamforming and Space Division Multiple Access (SDMA) techniques, adaptive antennas are able to...
A vision of future wireless networks is the coexistence of multiple access network technologies. Different access networks will coexist and the Internet Protocol will be the joint layer. Controlling the resources of these networks is very challenging. This paper deals with two data oriented access networks, the worldwide interoperability for microwave access (WiMAX) and the high speed downlink packet...
CDMA2000, WCDMA and WiMAX are three widely used 3G technologies. Since they share the same goal, which is to provide broader coverage and higher throughput in 3G networks, an impartial comparison of their performance is indispensable. However, they are based on different design principles and methodologies, which make the comparison challenging. This paper presents a comparative study of these technologies,...
In this paper, we focus on mobile-centered decision making in heterogeneous networks. We study the case where the JRRM decision is completely distributed so that mobile users have to decide to which of the available systems it is best to connect. To optimize their decision over the time, the mobiles implement a Q-learning algorithm that enables them to profit from their past experience. We study the...
In this work we aim to present some results to provide useful guidelines for the deployment of IMT-2000 systems like WiMAX and WCDMA, in terms of uplink cell throughput and cell coverage capacities. For this, a simple link level simulations planning tool, based on four established path loss models applicable to three different Brazilian cities were done and the results shown that WiMAX systems, for...
Mobile WiMAX, based on IEEE 802.16e, has been developed and is expected to be commercialized in late 2008 or early 2009. To further improve the system performance, spatial division multiple access (SDMA) enabled by adaptive antenna system (AAS) has been considered. In this paper, the relative performance improvement of SDMA based mobile WiMAX is investigated. Results show that AAS-enabled SDMA can...
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