Heterogeneous Traffics Research Articles

Active interference cancellation-aided QoS-aware distributed ARQ for cognitive radios with heterogeneous traffics

Abstract Relay-assisted Automatic Repeat reQuest (ARQ), which allows the relays instead of the source to carry out retransmissions of packets erroneously received at the destination, is an efficient cooperative transmission technique to improve link reliability with high spectrum efficiency in wireless networks. In cognitive radio (CR) systems, however, this relay-assisted ARQ could induce large latency, since a successful transmission of a packet may consume two idle timeslot or temporal spectrum holes. To overcome this limitation, an active interference cancellation (IC)-aided distributed relay-assisted ARQ method is proposed in this article to serve heterogeneous elastic traffics with diverse quality of service (QoS) demands in CR systems. Specifically, by applying our recently proposed distributed beamforming-based IC method in the physical layer, cognitive relays can exploit spatial spectrum holes (SSHs) to retransmit while keeping the interference to primary users at a tolerable level. Meanwhile, at the MAC layer, two scheduling policies, namely probabilistic and queue-length-based scheduling, are proposed to obtain an efficient allocation of temporal and SSHs to direct transmissions and retransmissions. The performance of the proposed schemes are analyzed and optimized by adjusting the scheduling parameters. As a result, the secondary users can obtain significant QoS gains, as validated by theoretical and simulation results.

A Gain-Computation Enhancements Resource Allocation for Heterogeneous Service Flows in IEEE 802.16 m Mobile Networks

This paper deals with radio resource allocation in fourth generation (4G) wireless mobile networks based on Orthogonal Frequency Division Multiple Access (OFDMA) as an access method. In IEEE 802.16 m standard, a contiguous method for subchannel construction is adopted in order to reduce OFDMA system complexity. In this context, we propose a new subchannel gain computation method depending on frequency responses dispersion. This method has a crucial role in the resource management and optimization. In a single service access, we propose a dynamic resource allocation algorithm at the physical layer aiming to maximize the cell data rate while ensuring fairness among users. In heterogeneous data traffics, we study scheduling in order to provide delay guaranties to real-time services, maximize throughput of non-real-time services while ensuring fairness to users. We compare performances to recent existing algorithms in OFDMA systems showing that proposed schemes provide lower complexity, higher total system capacity, and fairness among users.

IEEE 802.15.4 MAC With GTS Transmission for Heterogeneous Devices With Application to Wheelchair Body-Area Sensor Networks

In wireless personal area networks, such as wireless body-area sensor networks, stations or devices have different bandwidth requirements and, thus, create heterogeneous traffics. For such networks, the IEEE 802.15.4 medium access control (MAC) can be used in the beacon-enabled mode, which supports guaranteed time slot (GTS) allocation for time-critical data transmissions. This paper presents a general discrete-time Markov chain model for the IEEE 802.15.4-based networks taking into account the slotted carrier sense multiple access with collision avoidance and GTS transmission phenomena together in the heterogeneous traffic scenario and under nonsaturated condition. For this purpose, the standard GTS allocation scheme is modified. For each non-identical device, the Markov model is solved and the average service time and the service utilization factor are analyzed in the non-saturated mode. The analysis is validated by simulations using network simulator version 2.33. Also, the model is enhanced with a wireless propagation model and the performance of the MAC is evaluated in a wheelchair body-area sensor network scenario.

Resource allocation for end-to-end QoS provisioning in a hybrid wireless WCDMA and wireline IP-based DiffServ network

In the future UMTS network, the heterogeneous traffics of multimedia services demand various QoS provisioning. At the same time, the seamlessly conveying of information between mobile users and a hybrid network requires the networking from wireless to wireline domains. However, in both academia and industries, the end-to-end QoS provisioning in the integration of wireline and wireless networks remains a challenge. In this paper, a modeling of a hybrid wireless WCDMA and wireline IP-based DiffServ network is presented to investigate the resource allocation for end-to-end QoS provisioning for multimedia services. In the wireless domain, the mathematical modeling of the cross-layer model including the physical layer, the link layer and the network layer is built. The connection admission control scheme is implemented based on the cross-layer model to determine the amount of resource for different services. In the wireline domain, we define the mapping of QoS classes between UMTS and DiffServ networks according to different QoS requirements. We propose a bandwidth allocation scheme to provide satisfactory packet loss and delay guarantee in DiffServ networks. The final end-to-end admission control scheme combines the resource allocation and admission control in both wireless and wireline domains. The analytical and simulation results show that the proposed resource allocation and admission control schemes work cooperatively in the presented hybrid wireless and wireline networks to guarantee the end-to-end QoS requirements for multimedia services.

Multi-Constrained QoS Geographic Routing for Heterogeneous Traffic in Sensor Networks

Sensor networks that carry heterogeneous traffics and are responsible for reporting very time-critical important events necessitate an efficient and robust data dissemination framework. Designing such a framework, that can achieve both the reliability and delay guarantee while preserving the energy efficiency, namely multi-constrained QoS (MCQoS), is a challenging problem. Although there have been many research works on QoS routing for sensor networks, to the best of our knowledge, no one addresses the above three service parameters all together. In this paper, we propose a new aggregate routing model and a distributed aggregate routing algorithm (DARA) that implements the model for achieving MCQoS. DARA is designed for multi-sink, multipath and location aware network architecture. We develop probabilistic models for multipath reliability constraint, sojourn time of a packet at an intermediary node and node energy consumption. Delay-differentiated multi-speed packet forwarding and in-node packet scheduling mechanisms are also incorporated with DARA. The results of the simulations demonstrate that DARA effectively improves the reliability, delay guarantee and energy efficiency.

Optimum latency guarantee by using weighting methods in real time VOIP

In modern VoIP (Voice over Internet Protocol) communications, providing adequate bandwidth for latency guarantees due to real time environments is a stringent issue. In this paper system resources (e.g., bandwidth) are properly divided for delay optimization due to various traffic loads. A generic scheme in achieving optimal delay guarantees by using weighted fair queueing method is proposed. In our approach, network resource is allocated according to the value of queue-length product. The numerical results demonstrate that the optimal delay can be achieved under the proposed bandwidth allocation scheme. The proposed scheme has the advantages both on delay optimization and easy implementation. The policy depicted here meets the requirements of minimum delay under various traffic types and this will be beneficial on solving the stringent problem of delay guarantees in voice communications encountered in modern Internet networks. The main contribution of our approach is focused on adequately dividing the system resources to significantly improve the system delay due to heterogeneous input traffics.

Call Blocking Probability for Heterogeneous and Asymmetrical Traffics in a TD-CDMA System

We develop a mathematical model to analyze call-level performance of radio channel allocation of TD-CDMA systems supporting multitype heterogeneous and asymmetrical traffic. The mathematical model has multidimensional operations using random vectors or matrices to deal with multiple types of traffic and asymmetrical up-and-down transmission directions separately. Employing the mathematical model, we obtain call blocking probability for each type of traffic and the optimum time-slot switching-point with the smallest call blocking probability.

On‐Line Learning and Dynamic Capacity Allocation in the Traffic Management of Integrated Services Networks

AbstractA Traffic Monitoring Algorithm (TMA) is utilized to allocate channel capacities dynamically to heterogeneous traffics with time‐varying characteristics. The threshold parameters that characterize the operational characteristics of the TMA control the overall system performance, including traffic rejection rates and wasted capacity rates. In this paper an on‐line learning algorithm is introduced, to dynamically adapt the threshold parameters of the TMA for attaining a prespecified upper bound on the traffic rejection rate, at minimal cost in wasted capacity rate. The learning algorithm is analyzed and evaluated to expose its superior convergence characteristics.

Dynamic capacity allocation and hybrid multiplexing techniques for ATM wireless LANs

We consider digital wireless multimedia LANs and time-varying traffic rates. To deal effectively with the dynamics of the time-varying traffic rates, a Traffic Monitoring Algorithm (TMA) is deployed to dynamically allocate channel capacities to the heterogeneous traffics. The TMA is implemented as a higher level protocol that dictates the capacity boundaries within two distinct framed transmission techniques: a Framed Time Domain-Based (FTDB) technique and a Framed CDMA (FCDMA) technique. The performance of the TMA in the presence of the FTDB technique is compared to its performance in the presence of the FCDMA technique for some traffic scenarios. The performance metrics used for the TMA-FTDB and TMA-FCDMA combinations are channel capacity utilization factors, traffic rejection rates, and traffic delays. It is found that the TMA-FTDB is superior to the TMA-FCDMA when the speed of the transmission links is relatively low and the lengths of the transmitted messages are relatively short. As the speed of the transmission links and the length of the transmitted messages increase, the TMA-FCDMA eventually outperforms the TMA-FTDB.

Performance analysis of delay-loss priority mechanism using Markov modulated arrival stream

The authors propose a new mechanism to handle delay and loss requirements of ATM traffic simultaneously. It is designed to satisfy the different levels of cell-loss performance for two classes of heterogeneous nonreal-time ATM traffics as well as the delay and loss requirements of real-time traffics simultaneously. The cell arrivals of input streams are modelled by MMPP. Both a real-time buffer and a nonreal-time buffer are served by a common server. The buffer occupancies of each traffic are controlled by the partial buffer sharing scheme. The steady-state probabilities of queue-length distributions are obtained using the stochastic integral approach.