Network-supported layered multicast transport control for streaming media

Multicast is very efficient in distributing large volume of data to multiple receivers over the Internet. Layered multicast helps solve the heterogeneity problem in multicast delivery. Extensive work has been done in the area of layered multicast, for both congestion control and error control. In this paper, we focus on network-supported protocols for streaming media. Most of the existing work solves the congestion control and error control problems separately, and do not give an integrated, efficient solution. In this paper, after reviewing related work, we introduce our proposed protocols, RALM and RALF. The former is a congestion control protocol and the latter is an error control protocol. They work under the same framework and provide an integrated solution. We also extend RALM to RALM-II, which is compatible with TCP traffic. We analyze the complexity of the proposed protocols in the network and investigated their performance through simulations. We show that our solution achieves significant performance gains with reasonable additional complexity. © 2007 IEEE.published_or_final_versio

Router-assisted layered multicast

Several layered multicast protocols have been proposed for congestion control in real-time multicast applications. Most of them are pure end-to-end protocols, thus having difficulty in coordinating receivers and coping with traffic variations. In this paper, we propose RALM, a new receiver-driven router-assisted layered multicast protocol. RALM achieves much better performance at the expense of moderate additional complexity in the network. RALM is incrementally deployable. We evaluate RALM through simulations, and compare its performance with RLM, the well known layered multicast protocol.published_or_final_versio

Fading-aware packet scheduling algorithm in OFDM-MIMO systems

To maximize system throughput and guarantee the quality of service(QoS) of multimedia traffic in orthogonal frequency division multiplexing(OFDM) systems with smart antennas, a new packet scheduler is introduced to consider QoS requirements, packet location in the frame, and modulation level. In the frequency domain, several consecutive subchannels are grouped as a frequency subband. Each subband in a frame can be used to transmit a packet, and can be reused by several users in a multiple-input and multiple-output (MIMO) systems. In this paper, we consider the adaptive packet scheduling algorithms design for OFDM/SDMA system.Based on the BER requirements, all traffics are divided into classes.Based on such classification, a dynamic packet scheduler is proposed,which greatly improves system capacity, and can guarantee QoS requirements.Adaptive modulation is also applied in the scheduler. Then, the complexity analysis of these algorithms is given. When compared with existing schedulers, our scheduler achieves higher system capacity with much reduced complexity. The use of adaptive modulation further enhances the system capacity. Simulation results demonstrate that as the traffic load increases, the new scheduler has much better performance in system throughput, average delay, and packet loss rate.published_or_final_versio

Layered multicast with forward error correction (FEC) for Internet video

In this paper, we propose RALF, a new FEC-based error control protocol for layered multicast video. RALF embodies two design principles: decoupling transport layer error control from upper layer mechanisms and decoupling error control and congestion control at the transport layer. RALF works with our previously proposed protocol RALM - a layered multicast congestion control protocol with router assistance. RALF provides tunable error control services for upper layers. It requires no additional complexities in the network beyond those for RALM. Its performance is evaluated through simulations in NS2.published_or_final_versio

Ad hoc network routing

An ad hoc network is composed of nodes that may move arbitrarily and without the support of a stationary infrastructure. The dynamic nature of ad hoc networks makes it very challenging to realize routing and deliver data packets efficiently. This article discusses the challenges of ad hoc network routing, surveys existing routing algorithms, and provides a comparison of these algorithms.published_or_final_versio

Maximum throughput analysis and enhancement of slotted ALOHA for multihop ad hoc networks

In this paper, we analyze the maximum throughputs of slotted-ALOHA-based multihop ad hoc networks with and without capture, by considering the degree (number of neighbors) of each node, and, different from prior research, allowing each node to have a different transmission probability. We propose a novel enhanced slotted ALOHA scheme, in which each station adaptively transmits packets according to the degrees of the stations' neighbors. The analytical and simulation results show that the enhanced scheme can improve the network performance greatly.published_or_final_versio

A channel-condition and packet-length dependent scheduler in wireless OFDM systems

In this paper, a new scheduler, called Channel-Condition and Packet-Length Dependent Packet Generalized Processor Sharing (CPLD-PGPS) scheduler is proposed for orthogonal frequency-division multiplexing (OFDM) wireless communication systems. Based on PGPS, CPLD scheduler considers the condition of the physical channel and the length of packets at the same time, and optimally allocates the sub-carriers in a frame. With this scheduler, improved system BER, and correspondingly superior PER performance can be achieved. The system throughput is improved, while guaranteeing the required bandwidth, and providing long term fairness for all the traffic in the system. In order to reduce the algorithm complexity, a simplified CPLD is proposed, which maintains the system throughput as the original scheduler, and guarantees the system performance with properly set system parameters. Simulation results demonstrate the superior performance of the proposed scheduler. © 2004 IEEE.published_or_final_versio

CPLD-PGPS scheduler in wireless OFDM systems

In this paper, we propose a new scheduler for orthogonal frequency-division multiplexing (OFDM) wireless communication systems, called Channel-Condition and Packet-Length Dependent Packet Generalized Processor Sharing (CPLD-PGPS) scheduler. Based on PGPS, the CPLD scheduler considers both the physical channel condition and the length of packets, and optimally allocates the sub-carriers to different users. The total transmit power is adaptively allocated to each subcarrier. With this scheduler, the system can achieve better system BER performance, and correspondingly superior PER performance. The system throughput is improved, the required bandwidth is guaranteed, and long term fairness for all traffic in the system is provided. In order to reduce the complexity, a simplified algorithm is proposed, which maintains the system throughput as in the original scheduler, and guarantees the system performance with properly set system parameters. The superior performance of the proposed schedulers is demonstrated by simulation with multimedia traffic. © 2006 IEEE.published_or_final_versio

Chemical reaction optimization for the fuzzy rule learning problem

IEEE World Congress on Computational Intelligence (WCCI 2012), Brisbane, Australia, 10-15 June 2012 hosted three conferences: the 2012 International Joint Conference on Neural Networks (IJCNN 2012), the 2012 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE 2012), and the 2012 IEEE Congress on Evolutionary Computation (IEEE CEC 2012)In this paper, we utilize Chemical Reaction Optimization (CRO), a newly proposed metaheuristic for global optimization, to design Fuzzy Rule-Based Systems (FRBSs). CRO imitates the interactions of molecules in a chemical reaction. The molecular structure corresponds to a solution, and the potential energy is analogous to the objective function value. Molecules are driven toward the lowest energy stable state, which corresponds to the global optimum of the problem. In the realm of modeling with fuzzy rule-based systems, automatic derivation of fuzzy rules from numerical data plays a critical role. We propose to use CRO with Cooperative Rules (COR) to solve the fuzzy rule learning problem in FRBS. We formulate the learning process of FRBS in the form of a combinatorial optimization problem. Our proposed method COR-CRO is evaluated by two fuzzy modeling benchmarks and compared with other learning algorithms. Simulation results demonstrate that COR-CRO is highly competitive and outperforms many other existing optimization methods. © 2012 IEEE.published_or_final_versio

Medium access control with physical-layer-assisted link differentiation

In this paper, we develop medium access control (MAC) schemes for both contention and contention-free accesses over wireless local area networks and give performance analysis of these MAC protocols. User detection and multirate adaptation (MRA) modules are proposed in the physical layer (PHY) to assist link differentiation. With these two modules, for contention accesses, a new distributed queuing MAC protocol (PALD-DQMP) is proposed. Based on different users' channel states, PALD-DQMP makes use of a distributed queuing system to schedule transmissions. To support multimedia transmissions, an enhanced PALD-DQMP (E-PALD-DQMP) is designed by providing two-level optimized transmission scheduling for four access categories, thus eliminating both external and internal collisions among mobile stations. For contention-free accesses, based on the same PHY-assisted link differentiation provided by the two modules, a new multipolling MAC protocol (PALD-MPMP) is proposed, which not only reduces the polling overhead but also prioritizes transmissions according to their delay requirements. Performance analysis and simulation results show that our proposed protocols outperform the standard MAC protocols for both delay-sensitive and best-effort traffics. All these improvements are mainly attributed to the awareness of cross-layer channel state information and the consequent MRA scheme. © 2008 IEEE.published_or_final_versio