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Wireless Ad Hoc Networks have experienced great improvement over the past decade. However, IEEE 802.11 DCF, as the standard for Ad Hoc Networks, is still greatly influenced by hidden and exposed node problems. Lots of researches have been performed to solve them, but only a few of them have addressed the tradeoff between the two problems. This paper tries to balance the two problems by distributed...
This work presents a novel approach to select a packet from a set of packets that are waiting to be transmitted to different destinations. This approach aims to achieve proportional throughput for each different destination, taking the channel quality and prior successful transmissions into account.
Mobile cellular networks are now largely deployed, and mobile customers are used to place and to receive calls at any location. The network coverage is continuous, but radio conditions met by users are not homogeneous. Thus, data rate is varying according to user mobility. In this paper, we propose to discriminate terminals by their radio conditions in order to select which data has to be sent. More...
Call admission control (CAC) is a significant radio resource management (RRM) function for quality of service (QoS) provisioning in wireless networks. Different CAC schemes have been proposed and evaluated, most of them under the call blocking probability (CBP) achieved. On the other hand, CAC problem in multiclass wireless networks should not only be evaluated under the CBP achieved for every service...
In this paper, we report on a mobile broadband wireless access(MBWA) system field trial with fast low-latency access with seamless handoff orthogonal frequency division multiplexing (FLASH-OFDM), which was carried out at Sendai city in Japan. This paper focuses on coverage and downlink throughput performance, which are the most important criteria for assessing wireless data communication systems....
Fixed WiMAX can be a solution for delivering broadband wireless access, because of its low deployment costs and its offered bandwidth. But it is of great importance that this technology can offer the same network performance as its competitors. We therefore propose in this paper the results of extensive measurements of the network performance (i.e., throughput, latency, and jitter) of an 802.16 -based...
This paper presents experimental results on the throughput performance of IP and physical layer packets in the evolved UTRA uplink using single-carrier FDMA radio access. The IP packet performance is investigated using a base station and four sets of user equipment, in which medium access control (MAC) layer processing and key packet radio access techniques in the physical layer such as frequency...
Multi-channel MAC protocols are proposed to increase the capacity of wireless network. However, dynamic channel selection mechanism based on channel usage information from one-hop neighbor nodes causes multi-channel hidden node problems in a multi-channel multi-hop wireless network. In this paper, we propose a new approach of channel selection. Nodes snoop data channels during idle times and then...
The next generation of wireless communications systems will likely incorporate MIMO techniques in order to provide higher data rate multimedia services. Moreover, the transmission control protocol (TCP) is generally employed at the transport layer for reliable data communication. Thus, the optimization of TCP/RLP performance over MIMO systems is currently an important research area. In this paper,...
This paper presents the optimum control interval for intra-cell fractional transmission power control (TPC) for a shared data channel employing frequency domain channel-dependent scheduling and adaptive modulation and coding (AMC) in the evolved UTRA uplink using single-carrier (SC)-FDMA radio access. The simulation results show that the best attenuation factor in the fractional TPC is approximately...
We have recently introduced in the literature a new access control protocol for next generation wireless cellular networks, which showed superior performance in comparison to other (TDMA and WCDMA-based) protocols when integrating various types of multimedia traffic. In this Extended Abstract, we show that the use of stack protocols to resolve contention among contending multimedia terminals is not...
In underwater networks, when designing contention-based MAC protocols such as CSMA/CA, a long propagation delay should be considered. Particularly, most protocols like 802.11, the most typical CSMA/CA protocol, which utilize the RTS/CTS handshaking technique with network allocation vector (NAV), determine the NAV using a value of duration field in RTS/CTS. The duration value is determined with a fixed...
In this paper system level performance evaluation of channel aware schedulers that apply previously presented multiple input-multiple output (MIMO) link adaptation algorithms is given. The analyzed schedulers operate in single-user (SU) and in multi-user (MU) mode, and adapt either only modulation and coding scheme, or MIMO scheme in addition. The performance evaluation is done by comparative analysis...
In an IEEE 802.11 ad hoc wireless LAN, the listen interval (LI) of a power-saving (PS) station should be fixed at one even there is no data traffic or its remaining battery power is low. However, if the value of LI is allowed more than two (in units of beacon interval), 802.11 power management may completely fail. In this paper, we propose a novel power management protocol, named OFPM, which not only...
Standardization work is nearly complete on long term evolution (LTE) of the UMTS Terrestrial Radio Access and Radio Access Network which is aimed for commercial deployment in 2010. Goals for the evolved system include support for improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration...
We propose a parallel a posteriori probability (APP) decoding algorithm for increasing the decoding throughput of turbo codes. The parallel decoding algorithm divides a noisy codeword into multiple sub-blocks which are decoded in parallel. The authors in [1] proposed utilizing the forward and backward variables computed by neighbor sub-blocks in the previous iteration as the initial boundary conditions...
OFDMA-based IEEE802.16 implements among other features adaptive modulation and coding (AMC) which results in a different bit rate for each user depending on its position in the cell as well as the radio condition it experiences; users away from the base station experience lower throughput. In case of (intra-cell) mobility, the download time for the data user will thus depend on the different locations...
Wireless mesh networks will play an important role in the next-generation wireless communication systems as it can provide wide coverage and scalable broadband Internet access services. However, congestion in such networks may lead to throughput degradation, packet loss and longer transmission delay. Therefore, routing and traffic forwarding schemes which are aware of the congestion status of a wireless...
Antenna tilt is an effective inter-cell interference reduction technique which has been studied a lot previously in the CDMA-based systems. In this paper, we concentrate on the evaluations of the mechanical antenna downtilt in the uplink LTE networks. The SINR performance and the trade-off between the cell coverage and capacity are studied in a homogeneous scenario. Simulation results in Macro 1 show,...
In LTE uplink, the slow varying path gain and shadowing are compensated by the standardized open loop power control (OLPC). Further optimization of the system performance can be done via closed loop power control commands. In this contribution, it is shown that using such commands to control the interference caused by users to the system, it is possible to achieve a gain in the order of 20% on the...
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