Multiservice Wireless Networks Research Articles

Generation of 40 GHz/80 GHz OFDM based MMW source and the OFDM-FSO transport system based on special fine tracking technology

Abstract We have experimentally proposed and demonstrated a hybrid OFDM based optical MMW source and OFDM-FSO transport system employing special fine tracking technology. In this paper, 10 Gbps/40 GHz and 10 Gbps/80 GHz MMW source are successfully transmitted over 50-km and 25-km SMF as well as 20-m wireless link by employing variable length single mode fiber. 10 Gbps base band signal is successfully transmitted over 500-m FSO link with the assistance of special tracking and pointing technology. A position sensitive detector (PSD) is used in a fine tracking system, due to its much greater detection ability as compared to the conventional charge coupled device (CCD). Greater position resolution and high sensibility of PSD helps to communicate our signal over 500-m optical link. The limitation of dispersion and ISI effect in our wireless network are combat by employing appropriate length of cyclic prefix (CP) in our OFDM system. Here, we study the BER performance of the system by varying the length of CP. The proper length of CP boosts the system capacity and enhances the overall system performance. Low BER, good EVM (~ 12 % ), clear constellation diagrams proved the reliability and feasibility of our system as a prominent solution for multiservice wireless network.

Wideband photonic microwave channelization and image-reject down-conversion

A wideband photonic microwave channelization and image-reject down-conversion system is proposed and experimentally demonstrated. The broadband radio frequency (RF) and electrical local oscillator (LO) signals are applied to Mach–Zehnder modulators (MZMs) and be multiplexed for channelized reference. By employing DPMZMs, different optical frequency shifting LO signals for channelization are generated. Due to the frequency difference between the modulated RF signals and frequency shifted LO signals, multichannel intermediate frequency (IF) signals can be easily separated by the followed photonic I/Q receiver. Experimental results show that the RF signal with a bandwidth of 3 GHz could be down-converted into six IF signals with the same center frequency of 750 MHz and the same bandwidth of 500 MHz. The measured spurious free dynamic range (SFDR) is 101 dB•Hz 2∕3, the passband fluctuation is less than 0.5 dB; the channel isolation is over 22 dB, and the image-rejection is over 22 dB. A QPSK vector signals with 50 Msym/s and 16.5–19.5 GHz operating frequency is successfully demonstrated using the proposed scheme, and good EVMs and constellation diagrams are obtained. The proposed photonic channelization and image-reject down-conversion system may have potential applications in the RF frontends of future systems such as broadband integrated satellite communication and multi-service wireless networks.

A bandwidth allocation and energy-optimal transmission rate scheduling scheme in multi-services wireless networks

The energy-saving of mobile devices during their application offloading process has always been the research hotspot in the field of mobile cloud computing (MCC). In this paper, we focus on the scenario where multiple mobile devices with MCC and non-MCC services coexist. A bandwidth allocation and the corresponding transmission rate scheduling schemes are proposed with the objectives of simultaneously maximizing the overall system throughput and minimizing the energy consumption of individual mobile device with MCC service. To allocate the bandwidth to all mobile devices, two different algorithms are proposed, i.e., 0–1 integer programming algorithm and Lagrange dual algorithm. The transmission rate scheduling scheme for mobile device with MCC service is presented based on reverse order iteration method. The numerical results suggest that energy consumed by individual mobile device with MCC service can be remarkably saved while the overall system throughput can also be maximized. Moreover, the results show that 0–1 integer programming algorithm can get greater system throughput but has higher computational complexity, which means the algorithm is more suitable for small-scale systems, whereas Lagrange dual algorithm can achieve a good balance between the performance and computational complexity.

Next-generation bidirectional Triple-play services using RSOA based WDM Radio on Free-Space Optics PON

An innovative low cost reflective semiconductor amplifier (RSOA) based bidirectional Triple-play services (TPS) using wavelength division multiplexed radio on free-space-optics passive optical network (WDM-RoFSO-PON) is proposed and experimentally demonstrated to transmit data, voice and video services simultaneously. In this paper, the TPS (10 Gb/s data/voice and 1.49 Gb/s HDTV signal) are successfully transmitted over a 500 m free-space link in downstream and RSOA is utilized at the receiving site to broadcast 1.25 Gb/s data/voice signal over same free-space link in upstream by reusing the carrier, that makes the system cost-effective. High receiver sensitivity and signal-to-noise ratio (SNR), low bit-error-rate (BER) and low error vector magnitude (EVM), and excellent eye-diagrams in our proposed network build the system more reliable and stable with acceptable performance. Therefore, proposed WDM-RoFSO-PON could be the viable solution for future ubiquitous multiservice wireless network in the scenario of TPS.

Adaptive resource allocation framework for user satisfaction maximization in multi-service wireless networks

In order to capture and maintain a representative share of the wireless communication market, effective ways to manage the scarce physical resources of cellular networks are fundamental for cellular network operators. In this context, this paper proposes an adaptive Radio Resource Allocation algorithm that targets the user satisfaction maximization in cellular networks with multiple services. The proposed algorithm is mathematically derived from a utility-based cross-layer optimization framework and employs user weights as well as an innovative service weight that is adapted to meet the satisfaction target of the most prioritized service. Furthermore, the proposed algorithm is scalable to several services classes and can be employed in the current and future generations of wireless systems that guarantee orthogonality among the allocable resources. The performance evaluation is conducted in realistic scenarios of the downlink of an Orthogonal Frequency Division Multiple Access based cellular network serving video and Constant Bit Rate flows, where we assume imperfect Channel State Information at the transmitter. Significant gains in the joint system capacity were obtained, demonstrating that the adaptability and service prioritization allow the accomplishment of simultaneously maximizing the user satisfaction for distinct services.

Joint Customized Price and Power Control for Energy-Efficient Multi-Service Wireless Networks via S-Modular Theory

In this paper, the problem of joint utility-based customized price and power control in multi-service wireless networks is addressed via S-modular theory. Each user is associated with a generic two-variable net utility function. The latter takes a different form based on the type of the requested service, and depends on both user’s uplink transmission power and the price he is willing to pay to achieve his quality of service prerequisites. The joint customized price and power control problem is formulated as a two-variable optimization problem and confronted as a non-cooperative distributed game. The S-modular theory is adopted to solve the corresponding optimization problem. The existence of the game’s Nash equilibrium point with respect to both user’s uplink transmission power and price is analytically shown, while game convergence is also proven. A distributed and iterative algorithm for computing the two-variable Nash equilibrium point is also presented. The optimal price and uplink transmission power are both determined simultaneously in a distributed manner while the control intelligence and the decision making process lie at the user. The performance of the proposed approach is evaluated via modeling and simulation and its superiority compared to other state of the art approaches is illustrated especially in terms of energy efficiency.

Improvement in the Priority Handoff Scheme for Multi-Service Wireless Mobile Networks

Improvement in the Priority Handoff Scheme for Multi-Service Wireless Mobile Networks

Channel Allocation to Multiservice Wireless Networks: A Collocation—Based Approach to Enhance Spectrum Utilization

A channel allocation (CA) scheme is proposed for wireless networks serving multiple services. The CA scheme is based on collocating the base stations of the wireless networks and restricting their coverage over common cells. The increased coverage granularity makes feasible a more efficient frequency reuse. A genetic algorithm approach is adopted to minimize the number of channels required by the multiservice networks, taking into account the intranetwork and intraservice constraints over a specific coverage area. To validate the proposed scheme and investigate its performance, the Philadelphia benchmark network is employed. Simulation results corresponding to a mix of digital TV and mobile services of various profiles demonstrate the capability of the proposed scheme to optimally allocate channels to multiservice wireless networks.

PluralisMAC: a generic multi-MAC framework for heterogeneous, multiservice wireless networks, applied to smart containers

Developing energy-efficient MAC protocols for lightweight wireless systems has been a challenging task for decades because of the specific requirements of various applications and the varying environments in which wireless systems are deployed. Many MAC protocols for wireless networks have been proposed, often custom-made for a specific application. It is clear that one MAC does not fit all the requirements. So, how should a MAC layer deal with an application that has several modes (each with different requirements) or with the deployment of another application during the lifetime of the system? Especially in a mobile wireless system, like Smart Monitoring of Containers, we cannot know in advance the application state (empty container versus stuffed container). Dynamic switching between different energy-efficient MAC strategies is needed. Our architecture, called PluralisMAC, contains a generic multi-MAC framework and a generic neighbour monitoring and filtering framework. To validate the real-world feasibility of our architecture, we have implemented it in TinyOS and have done experiments on the TMote Sky nodes in the w-iLab.t testbed. Experimental results show that dynamic switching between MAC strategies is possible with minimal receive chain overhead, while meeting the various application requirements (reliability and low-energy consumption).

Robustness of optimal channel reservation using handover prediction in multiservice wireless networks

The aim of our study is to obtain theoretical limits for the gain that can be expected when using handover prediction and to determine the sensitivity of the system performance against different parameters. We apply an average-reward reinforcement learning approach based on afterstates to the design of optimal admission control policies in mobile multimedia cellular networks where predictive information related to the occurrence of future handovers is available. We consider a type of predictor that labels active mobile terminals in the cell neighborhood a fixed amount of time before handovers are predicted to occur, which we call the anticipation time. The admission controller exploits this information to reserve resources efficiently. We show that there exists an optimum value for the anticipation time at which the highest performance gain is obtained. Although the optimum anticipation time depends on system parameters, we find that its value changes very little when the system parameters vary within a reasonable range. We also find that, in terms of system performance, deploying prediction is always advantageous when compared to a system without prediction, even when the system parameters are estimated with poor precision.

Distributed Uplink Power Control in Multiservice Wireless Networks via a Game Theoretic Approach with Convex Pricing

In this paper, the problem of efficient distributed power control via convex pricing of users' transmission power in the uplink of CDMA wireless networks supporting multiple services is addressed. Each user is associated with a nested utility function, which appropriately represents his degree of satisfaction in relation to the expected trade-off between his QoS-aware actual uplink throughput performance and the corresponding power consumption. Initially, a Multiservice Uplink Power Control game (MSUPC) is formulated, where each user aims selfishly at maximizing his utility-based performance under the imposed physical limitations and its unique Nash equilibrium point is determined. Then the inefficiency of MSUPC game's Nash equilibrium is proven and a usage-based convex pricing policy of the transmission power is introduced, which offers a more effective approach compared to the linear pricing schemes that have been adopted in the literature. Consequently, a Multiservice Uplink Power Control game with Convex Pricing (MSUPC-CP) is formulated and its unique Pareto optimal Nash equilibrium is determined. A distributed iterative algorithm for computing MSUPC-CP game's equilibrium is proposed, while the overall approach's efficiency is illustrated via modeling and simulation.

Numerical analysis of multiparameter strategy of access in multiservice wireless cellular communication networks

Numerical methods are suggested for investigation of the indices of quality of service in multiservice wireless cellular communication networks, in which the access of different-type calls is controlled by the multiparameter strategy limiting the number of new and handover calls of different-type traffics in channels of a cellular network component. The exact method is based on the multiplicative solution, while the approximate method uses the principles of phase enlargement of the states of stochastic systems. Results of computational experiments are displayed.

Design of Fair Weights for Heterogeneous Traffic Scheduling in Multichannel Wireless Networks

Fair weights have been implemented to maintain fairness in recent resource allocation schemes. However, designing fair weights for multiservice wireless networks is not trivial because users' rate requirements are heterogeneous and their channel gains are variable. In this paper, we design fair weights for opportunistic scheduling of heterogeneous traffic in orthogonal frequency division multiple access (OFDMA) networks. The fair weights determine each user's share of rate for maintaining a utility notion of fairness. We then present a scheduling scheme which enforces users' long term average transmission rates to be proportional to the fair weights. The proposed scheduler takes the advantage of users' channel state information and the inherent flexibility of OFDMA resource allocation for efficient resource utilization. Furthermore, using the fair weights allows flexibility for realization of different scheduling schemes which accommodate a variety of requirements in terms of heterogeneous traffic types and user mobility. Simulation based performance analysis is presented to demonstrate efficacy of the proposed solution in this paper.

Probabilistic call admission control in wireless multiservice networks

A new probabilistic call admission control scheme is proposed for multiservice wireless networks. The new scheme gradually suppresses the admission rate of the new calls and of the calls of each service class (SC) supported considering their priorities independently. The scheme is examined both for a single SC and for multiple SCs under general conditions. The analysis employs Markov chain theory and yields analytical expressions for the call blocking probabilities. The proposed analytical method was validated via simulations employing different distributions for the channel holding time; the simulations demonstrated the accuracy of the proposed framework.

Bandwidth Reallocation for Bandwidth Asymmetry Wireless Networks Based on Distributed Multiservice Admission Control

This paper addresses when and how to adjust bandwidth allocation on uplink and downlink in a multi-service mobile wireless network under dynamic traffic load conditions. Our design objective is to improve system bandwidth utilization while satisfying call level QoS requirements of various call classes. We first develop a new threshold-based multi-service admission control scheme (DMS-AC) as the study base for bandwidth re-allocation. When the traffic load brought by some specific classes under dynamic traffic conditions in a system exceeds the control range of DMS-AC, the QoS of some call classes may not be guaranteed. In such a situation, bandwidth re-allocation process is activated and the admission control scheme will try to meet the QoS requirements under the adjusted bandwidth allocation. We explore the relationship between admission thresholds and bandwidth allocation by identifying certain constraints for verifying the feasibility of the adjusted bandwidth allocation. We conduct extensive simulation experiments to validate the effectiveness of the proposed bandwidth re-allocation scheme. Numerical results show that when traffic pattern with certain bandwidth asymmetry between uplink and downlink changes, the system can re-allocate the bandwidth on uplink and downlink adaptively and at the same time improve the system performance significantly.

Analysis and optimization of multiservice mobile systems

Methods of analysis and optimization of distributed multidimensional queues with priorities and dynamic control of the quality of services for sublevels of controlling multiple accesses to the medium access control in 3G/4G multiservice mobile and wireless networks are developed. A theoretical-game formulation of the problem of distributed dynamic control of the quality of services is proposed. The results obtained are based on the development of a numerical-analytical method for balancing load intensities.

QoS-driven adaptive congestion control for voice over IP in multiservice wireless cellular networks

This work establishes a QoS-driven adaptive congestion control framework that provides QoS guarantees to VoIP service flows in mixed traffic scenarios for wireless cellular networks. The framework is composed of three radio resource management algorithms: admission control, packet scheduling, and load control. The proposed framework is scalable to several services and can be applied in any current or future packet-switched wireless system. By means of dynamic system-level simulations carried out in a specific case study where VoIP and Web service flows compete for shared access in an HSDPA wireless network, the proposed framework is able to increase the overall system capacity twofold depending on the traffic mix, while keeping the system operating optimally in its target QoS profile.

Performance analysis of multi-service wireless network: An approach integrating CAC, scheduling, and buffer management

Traffic management (TM) mechanisms such as Call Admission Control (CAC), Scheduling, and Buffer Management (BM) play a key role in the design of multi-service wireless network by providing service differentiation from diverse applications and assigning the network resources (radio channels or buffer) according to the quality of service (QoS) requirements of each service class. We propose in this work two new models that integrate CAC, Scheduling, and BM in the design of multi-service wireless network. By presenting their Markovian models and their performance metrics, we investigate their respective design tradeoffs and compare their performance.

Optimizing Admission Control for Multiservice Wireless Networks With Bandwidth Asymmetry Between Uplink and Downlink

Next-generation wireless networks need to support multiclass services with asymmetric bandwidth allocation between uplink and downlink to match the asymmetric traffic load brought by some data services. For the design of call admission control (CAC) policy in such networks, how to decrease the average system cost is a key issue. In this paper, we study the optimal admission policy for minimizing the system cost. We consider the CAC problem as a decision process. By modeling the admission control problem into a Markov decision process (MDP) and analyzing the corresponding value function, we obtain some monotonicity properties of the optimal policy. These properties suggest that the optimal admission control policy for the bandwidth asymmetry wireless networks should have a threshold structure and the threshold specified for a class of calls may change with the system state. Due to the prohibitively high complexity for computing the thresholds in a system with large state-space, we propose a heuristic CAC policy called call-rate-based dynamic threshold (CRDT) policy to approximate the theoretical optimal policy based on the insights we obtain from the modeling and the analytical study on the properties of the optimal policy. The CRDT policy is efficient and can be easily implemented. The numerical results show that the performance of average system cost of the proposed CRDT policy is close to that of the optimal policy from the MDP model and is better than that of some known existing CAC schemes, including those performing well in bandwidth asymmetry wireless networks

Developing a QoS framework for media streaming over TDMA/TDD wireless networks

Recent advances in wireless technology are enabling the design and deployment of multiservice wireless networks. In order to be able to meet the QoS requirements of the various applications, it is essential to deploy QoS provisioning mechanisms. In this paper we present a QoS framework to support various types of services in a wireless networking environment. In particular, the proposed framework is used to design various QoS provisioning mechanisms for time-constrained variable bit-rate applications. Under this QoS framework we propose various Resource Request (RR) mechanisms. We carry out a comparative study of the proposed schemes. Our simulation results show the effectiveness of the mechanisms when supporting media streaming services, such as MPEG-4 video communications.