1,721,130 research outputs found
Efficient scheduling techniques for high data-rate wireless personal area networks
No full textAmong several wireless network scenarios, the in-home environment is one of the more challenging in recent years. In particular, the Wireless Personal Area Network (WPAN) seems one of the most interesting application scenario as that networks work in small area for delivering multimedia traffic. The IEEE 802.15.3 is the emerging standard for WPAN. This standard is designed to provide low complexity, low cost and low power-consumption for personal area networks that manage multimedia traffic, video and audio between different devices in a small area environment. The piconet is the basic topology structure of a WPAN and it is defined as group devices where one of them is the PicoNet Coordinator (PNC). A PNC manages the synchronisation and controls the data traffic of the system. This paper proposes some scheduling techniques to be used at the Medium Access Control (MAC) layer for high data-rate WPANs. The proposed scenario is composed of several nodes generating both data and video traffic respecting the application scenario often foreseen for high-rate WPANs. Two scheduling methods are proposed which, exploiting the traffic growth, can improve the performance of the network in terms of throughput and delay. In particular the performance of an adaptive technique and an optimum technique are compared with the performance of the fixed technique considered in the standard
A MAC layer traffic-priority management technique in CDMA based ad-hoc networks
No full textRecently, ad-hoc networks have obtained a growing interest due to their advantages in many practical applications. One of the most critical points is the definition of an efficient medium access control (MAC) protocol that allows the transmission of packets generated by a node and routing of packets arriving from other nodes. Moreover the growth of several applications with different requirements in terms of QoS has raised the problem to manage their priority also at the MAC layer. This paper deals with a traffic priority management technique at the MAC layer based on the code division multiple access (CDMA) scheme, where an adaptation of the used spreading factor to the network congestion is foreseen in order to minimize the energy consumption and maximize the network throughpu
Adaptive rate admission control for DS-CDMA cellular systems
No full textThe paper proposes an adaptive admission control (AC) policy, that reduces call dropping probability, resorting to rate adaptation in accordance with the instantaneous connection configurations. We describe the philosophy of the proposed adaptive scheme and analyze the effective call dropping probability when considering a single cell UMTS scenario with an additive white Gaussian noise (AWGN) channel. Our simulations demonstrate that, by employing the proposed scheme, the network performance can be extremely increased while the quality of service (QoS) requested is respected
Multimedia traffic management at MAC layer in IEEE 802.15.3a personal area networks
No full textAmong several wireless network scenarios, the in-home environment is one of the more challenging in the last years. In particular, the wireless personal area network (WPAN) seems one of the most interesting application scenario, as that networks work in small area for delivering multimedia traffic. The IEEE 802.15.3 is the emerging standard for WPAN. This standard is designed to provide low complexity, low cost and low power-consumption for personal area networks that manage multimedia traffic, video and audio between different devices in a small area environment. The piconet is the basic topology structure of a WPAN and it is defined as group devices, where one of them is the piconet coordinator (PNC). A PNC manages the synchronization and controls the data traffic of the system. This paper proposes an adaptive medium access control (MAC) technique for high data-rate WPANs. The proposed system aims to maximize the performance of the WPAN in terms of throughput, considering multimedia traffic
Medium access control protocol for CDMA ad hoc networks
No full textRecently, ad hoc networks have obtained a growing interest because of their advantages in many practical applications. One of the most critical points is the definition of an efficient medium access control (MAC) protocol that allows the transmission of packets generated by a node and routing of packets arriving from other nodes. A MAC technique is presented based on the code division multiple access (CDMA) scheme that adapts the used spreading factor to the network congestion in order to minimise the energy consumption and maximise the network throughput
Efficient fast packet switching fabric using neural networks
No full textThe authors propose a new fast packet switching fabric with input shared buffers, where a neural network of the Hopfield type is used to take optimum decisions for switching packets and improve the switching performance
A novel MAC technique for ad-hoc CDMA networks
No full textIn the recent years the high-speed data networking in a wireless infrastructure has became one of the most interesting topic both in industrial and research field. Among different standards and data rates one of the most important challenge in the future is established by the ad-hoc networks. They differs from the classical wireless local area networks (WLANs) for the absence of a coordinator device. In such networks the data exchange is autonomously routed by the devices that assume also the function of network nodes. One of the most interesting topics in wireless ad-hoc networks is the medium access control (MAC) protocol because each node have to sent packets generated by itself and route packets from other nodes; moreover, due to the absence of a coordination device, each node have to perform some algorithm in order to know which are the neighbor nodes. In this paper a MAC technique for code division multiple access (CDMA) networks is proposed, taking into account the adaptation of the spreading code in order to minimize the total network congestion
Analysis and comparison of scheduling techniques for a BWA OFDMA mobile system
No full textIn the last few years the wireless metropolitan area networks (WMANs) have increased their popularity and attracted the interest of important research groups all over the world; as a consequence, several standards have been proposed. Among them, the IEEE 802.16 (WiMAX) is one of the most promising standard to carry out a full-service broadband wireless network in an urban and suburban area. This standard provides high data rate within a wide coverage area with low implementation costs, possibility of multi-traffic communications, and different network topologies. This paper deals with the analysis and performance comparison of different scheduling techniques for WiMAX networks for allowing quality of service (QoS) differentiation when different types of applications have to be supported and achieving a fair distribution of resource among users. In particular, the focus here is on the resource allocation problem for the case of mobile stations (MSs) active in an urban environment. The proposed scheduling algorithms exploit the orthogonal frequency division multiple access (OFDMA) scheme with adaptive modulation techniques in order to achieve a better network behavior. The performance of the proposed approaches will be derived here by means of theoretical analysis and computer simulations
A priority based admission control strategy for WCDMA systems
No full textFuture wireless systems need higher support in terms of QoS support. In particular, when several connections with different QoS attributes are allowed, a prioritization system has to be foreseen. In UMTS and other systems that exploit the WCDMA approach, the problem of mitigating multiple access interference arises, too. Admission control algorithms have been introduced in the literature in order to prevent any congestion status in the network. An admission control algorithm that works by exploiting the current interference level is presented; moreover, each type of traffic is managed in order to respect its QoS in terms of priority
A MAC technique for CDMA based ad-hoc networks
No full textRecently, ad-hoc networks have obtained a growing interest due to their advantages in many practical applications. One of the most critical points is the definition of an efficient medium access control (MAC) protocol that allows the transmission of packets generated by a node and routing of packets arriving from other nodes. This paper deals with a MAC technique based on code division multiple access (CDMA) scheme that adapts the used spreading factor to the network congestion in order to minimize the energy consumption and maximize the network throughput
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