Scheme In IEEE Research Articles

Resource Management and QoS Provisioning for Duplex Services in IEEE 802.16

Duplex services are multimedia services that requires good connectivity in both uplink and downlink such as VoIP, video conferencing and interactive gaming. A weak connection in either direction may cause degradation of performances and dissatisfaction of user experience. Most researchers do not consider this issue and treat resource allocations in uplink and downlink independently. For this reason, the conventional resource management schemes do not guarantee a good duplex connectivity. Generally, duplex schemes require some relation or information to be exchanged between uplink and downlink resource allocation processes. The existing duplex resource allocation schemes, however, have high complexity and do not adhere to the IEEE 802.16 standard. In this paper, we propose a duplex resource management scheme for IEEE 802.16 network to enhance the user experience and to improve the network performances. The proposed resource management scheme is a MAC layer function that co-relates the uplink and downlink allocation processes using a newly proposed duplex variable. Simulation studies show that the proposed scheme brings significant benefit to duplex services in the IEEE 802.16 networks and outperforms the conventional and existing schemes in terms of uplink and downlink transmission gap, QoS performances and fairness.

A new codebook design scheme for fast beam searching in millimeter-wave communications

To overcome imperfection of exhaustive based beam searching scheme in IEEE 802.15.3c and IEEE 802.11ad and accelerate the beam training process, combined with the fast beam searching algorithm previously proposed, this paper proposed a beam codebook design scheme for phased array to not only satisfy the fast beam searching algorithm's demand, but also make good use of the advantage of the searching algorithm. The simulation results prove that the proposed scheme not only performs well on flexibility and searching time complexity, but also has high success ratio.

Transmission Power Control for IEEE 802.15.6 Body Area Networks

Energy consumption is an important issue in body area networks (BANs). In this letter, we propose an energy efficient transmission power control scheme for IEEE 802.15.6 BANs, which can improve energy efficiency by adaptively adjusting the transmit power in an on-demand way to adapt to varying channel environments. Simulations are performed to evaluate the performance, and it is shown that the proposed power control scheme outperforms traditional ones in terms of energy efficiency without significant reliability degradation.

IEEE 802.11 무선랜에서의 멀티미디어 전송을 위한 스케일러블 비디오 코딩 인지형 재전송 기법

멀티미디어 스트리밍을 위해 널리 사용되고 있는 스케일러블 비디오 코딩 (Scalable Video Coding: SVC)의 경우 가변적인 네트워크 상황에 적응적으로 대처하기 위해 기본 계층과 향상 계층으로 나누어 데이터를 인코딩하여 전송하게 된다. 특히 향상 계층의 디코딩은 기본 계층의 데이터가 수신되었을 때 가능하다는 특성을 가지고 있다. 이러한 특성에도 불구하고 IEEE 802.11 무선랜에서의 재전송 기법은 기본/향상 계층의 특성을 고려하지 않고 설계되어 있다. 본 논문에서는 스케일러블 비디오 코딩의 특성을 고려한 새로운 재전송 기법을 제안한다. 제안한 재전송 기법은 기본 계층과 향상 계층을 나누어서 채널상태에 따라 디코딩에 필요한 수 만큼의 데이터를 재전송하여 불필요한 재전송을 방지하고 총 전송시간을 감소시킨다. 시뮬레이션 결과는 제안한 재전송 기법이 기존의 재전송 기법보다 불필요한 데이터 전송을 12.6% 감소시키며 이로 인해 전송 시간도 6.6~19.1% 만큼 감소됨을 보여준다. Scalable video coding (SVC) encodes multimedia data into a base layer and enhancement layers to cope with variable network conditions in an adaptive manner. In SVC, enhancement layers can be decoded only when the base layer is successively received. However, existing works on SVC transmissions in IEEE 802.11 WLANs do not fully investigate this characteristic and thus their performance can be degraded. In this paper, we propose a SVC-aware retransmission (SAR) scheme in IEEE 802.11 WLANs. The SAR scheme applies different retransmission policies for base and enhancement layers by obtaining the optimal number of frames to be retransmitted. As a result, the SAR scheme can reduce unnecessary retransmissions and minimize the transmission latency. Simulation results demonstrate that the SAR scheme can reduce unnecessary data transmission by 12.6% and the transmission latency by 6.6~19.1% compared to conventional retransmission schemes.

Coordinated Interleaving Access Scheme for IEEE 802.11p Wireless Vehicular Networks

Coordinated Interleaving Access Scheme for IEEE 802.11p Wireless Vehicular Networks

The Design of an AP-Based Handoff Scheme for IEEE 802.11 WLANs

The Design of an AP-Based Handoff Scheme for IEEE 802.11 WLANs

A new media access control layer quality of service multicast scheme for IEEE 802.11s-based wireless mesh networks

We propose a new media access control (MAC) layer enabling quality of service (QoS) multicast scheme for IEEE 802.11s networks, where a unicast routing protocol called hybrid wireless mesh protocol (HWMP) is defined. The HWMP protocol is more adapted for best effort traffic that is why its usage is not suitable for real time multimedia applications. The goal of our proposed mechanism is to take into account multicast communication under QoS constraints for the IEEE 802.11s mesh networks where no QoS multicasting has been defined. Our multicasting scheme handles QoS guarantee for real time applications. Indeed, our scheme is based on finding the QoS multicast tree thanks to an end-to-end delay evaluation to cover multicast services. A QoS multicast tree is constructed based on the proactive tree HWMP mechanisms. Simulations results, using Network Simulator 3 (NS 3), show that our scheme improves data multicast transmission overhead as well as network throughput.

Real-time-service-based Distributed Scheduling Scheme for IEEE 802.16j Networks

Supporting Quality of Service (QoS) guarantees for diverse multimedia services is the primary concern for IEEE802.16j networks. A scheduling scheme that satisfies the QoS requirements has become more important for wireless communications. We proposed an adaptive nontransparent-based distributed scheduling scheme (ANDS) for IEEE 802.16j networks. ANDS comprises three major components: Priority Assignment, Resource Allocation, Preserved Bandwidth Adjustment. Different service-type connections primarily depend on their QoS requirements to adjust priority assignments and dispatch bandwidth resources dynamically. Meanwhile, we promote the connections, which do not satisfy QoS requirements, to avoid the delay and starvation. Simulation results show that our APS methodology outperforms the representative scheduling approaches in both QoS satisfaction and maintains fairness in starvation prevention.

An accelerating handover process scheme for IEEE 802.16j multi-hop relay networks

IEEE 802.16j multi-hop relay network systems provide the mobile wireless communication environment. In such network systems, the handover scanning procedure allows a mobile station (MS) to obtain the information about the handover target base stations (BSs) or relay stations (RSs). The network systems need more time to negotiate the association parameters and to handle scanning the BSs and the RSs when the number of BS and RS increases. It results in more overhead for the handover scanning procedure. In order to accelerate the handover process and reduce the transmission interruption, efficient handover scanning procedure schemes and corresponding algorithms must be developed and designed. A novel relative angle computing algorithm is proposed in this article to accelerate the handover process by taking into account the moving behavior of the MS, and the distances among the MS, the RS, and the BS. The main idea of this algorithm is to reduce the management information overhead and to estimate the potential moving path of the MS in the wireless mobile communication networks. By using the proposed scheme, we eliminate the unnecessary associations and scanning intervals, and reduce the handover scanning procedure efficiently. Simulation result demonstrate the superior performance of our proposed scheme and its ability to strike the appropriate performance in the handover overhead and the message delay for IEEE 802.16j multi-hop relay network systems.

HARQ Performance Analysis in IEEE 802.16m System

In this paper we simulate and analyze the system performance of implementing two Hybrid Automatic Retransmission Request (HARQ) architectures for IEEE 802.16m system, one is a modified Type I HARQ architecture with adaptive modulation and coding (AMC) scheme and the other is the Chase Combining. In the simulation, the buffer size of HARQ has been set to certain limit and under the condition of having the packet error ratio (PER) limited by 10% then the selection of proper HARQ structure with suitable AMC scheme for IEEE 802.16m system has been proposed for mobile speeds at 3 km/hr, 80 km/hr or 350 km/hr and with a distance of 300m between the mobile station and its serving base station.

Mathematical analysis of burst transmission scheme for IEEE 802.3az energy efficient Ethernet

The IEEE P802.3az Energy Efficient Ethernet (EEE) protocol specifies a Low Power Idle (LPI) mode in which Ethernet device can save energy by turning off components when its queue is empty, and defines a scheme for coordinating the transitions between the LPI and active modes. Depending on when Ethernet devices enter and exit the LPI mode, two schemes have been proposed: the frame transmission scheme and the burst transmission scheme. P. Reviriego et al. proposed the burst transmission scheme (the same as the packet coalescing scheme by Christensen et al.) where the link becomes active when either a fixed number of packets have arrived or a fixed time is passed from the epoch that the first packet has arrived. They showed by simulation that the burst transmission scheme has significantly lower energy consumption than the frame transmission scheme of EEE. In this paper, we provide an analytic model of the burst transmission scheme and obtain its energy consumption and packet delay. Our analytic results match the simulation results. In numerical results, we find the maximal timer which minimizes the energy consumption while satisfying the maximal packet delay within a pre-determined level.

A High Capacity Low Latency Guaranteed Time Slot Allocation Scheme for IEEE 802.15.4

A High Capacity Low Latency Guaranteed Time Slot Allocation Scheme for IEEE 802.15.4

An Adaptive Optimization Scheme for IEEE 802.11 DCF to Achieve Fairness Between Uplink and Downlink Flows

The data traffic needed to be transferred by APs is much more than the other STAs in the IEEE802.11 DCF networks. However, APs access the wireless link with the same priority as STAs, and thus the throughput between uplink and downlink is of great injustice. In this paper, an adaptive optimization scheme is proposed to achieve fairness between uplink and downlink flows. APs monitor the growing real-time data traffic, and when the network system is in heavy traffic, APs could adaptively adjust the contention window to achieve fairness. Detailed simulation results show that the scheme can effectively adapt to various networks different in data flow numbers and packet size, and consequently achieve fairness between uplink and downlink flows with the total throughput increased.

Queuing Scheme for Improved Downlink Throughput on WLANs

A transmission queuing scheme is described that increases downlink throughput on wireless local area networks (WLANs) while also increasing the total throughput. When the amount of uplink traffic increases on a WLAN, the carrier sense multiple access with collision avoidance (CSMA/CA) protocol, which is the prescribed scheme for IEEE 802.11 WLAN channel access, may substantially reduce the rate of downlink data frame transmission. This results in severe throughput degradation for mobile stations with downlink traffic. The proposed scheme comprises a transmission control function based on consecutive transmission, as described in the IEEE 802.11e standard, and a dynamic queue prioritization algorithm. Simulation results demonstrate that the proposed scheme increases the maximum total throughput for uplink and downlink traffic by 17% compared with the conventional distributed coordination function (DCF) scheme and that it reduces the difference between uplink and downlink throughput. In an environment where transmission errors occur, the difference in throughput is reduced by about 50% compared with the conventional schemes.

Utility-based admission control for mobile WiMAX networks

This paper presents a novel utility-based connection admission control (CAC) scheme for IEEE 802.16e broadband wireless access networks. We develop specific utility functions for real-time and non-real-time services coupled with a handover process. Given these utility functions we characterize the network utility with respect to the allocated bandwidth, and further propose a CAC algorithm which admits a connection that conducts to the greatest utility so as to maximize the total resource utilization. The simulation results demonstrate the effectiveness of the proposed CAC algorithm in terms of network utility.

Analysis of Impact of TXOP Allocation on IEEE 802.11e EDCA under Variable Network Load

In this paper, we investigate the impact of transmission opportunity (TXOP), arbitration interframe space (AIFS), and contention window on the performance of an IEEE 802.11e cluster with four traffic classes under Poisson frame arrivals. We derive an analytical model of the cluster using queuing model of individual nodes, discrete time Markov chain, and probabilistic modeling of the backoff process. The analytical model demonstrates the complex interaction between TXOP, on one side, and AIFS and contention window, on the other. We derive saturation and stability points for all traffic classes and discuss their dependency on TXOP allocations. Our results indicate that use of nonzero TXOP parameter under Poisson frame arrivals improves performance slightly by separating points of saturation and instability. More substantial performance improvements should be expected by deploying TXOP differentiation under bursty traffic. Since all traffic classes need to operate in stable, nonsaturated regime, this work has important implications for the design of congestion control and admission control schemes in IEEE 802.11e clusters.

Dynamic admission control and bandwidth reservation for IEEE 802.16e mobile WiMAX networks

The article presents a dynamic connection admission control (CAC) and bandwidth reservation (BR) scheme for IEEE 802.16e Broadband Wireless Access networks to simultaneously improve the utilization efficiency of network resources and guarantee QoS for admitted connections. The proposed CAC algorithm dynamically determines the admission criteria according to network loads and adopts an adaptive QoS strategy to improve the utilization efficiency of network resources. After new or handoff connections enter the networks based on current admission criteria, the proposed adaptive BR scheme adjusts the amount of reserved bandwidth for handoffs according to the arrival distributions of new and handoff connections in order to increase the admission opportunities of new connections and provide handoff QoS as well. We conduct simulations to compare the performance of our proposed CAC algorithm and BR scheme with that of other approaches. The results illustrate that our approach can effectively improve the network efficiency in terms of granting more connections by as large as about 22% in comparison with other schemes, and can also guarantee adaptive QoS for admitted new and handoff connections.

A delay-sensitive gts allocation scheme in ieee 802.15.4 for wireless audio applications

The IEEE 802.15.4 standard is designed for low rate wireless personal area networks, targeting at low cost and low power communications. It also provides a guaranteed time slot (GTS) mechanism to support time sensitive wireless audio applications. The coordinator allocates specific durations within a superframe to guarantee reliability and performance of data deliveries. However the existing first-come-first-served (FCFS) GTS allocation policy can result in the scheduling inflexibility in low-latency data transmission, since it doesn't take into account the traffic specification, delay requirements and the energy resources. In this paper, an adaptive GTS allocation scheme is developed to satisfy the delay constraints of wireless audio applications. Based on recent GTS usage feedback, each device in the WPAN is dynamically allocated a priority number. Then the devices are allocated specific slots according to this priority information. The devices with higher priorities indicate more recent traffic and have higher probabilities to transmit their data in the subsequent superframe. The performance of the scheme is analyzed using Markov chain. The analytical model is validated through simulation results, indicating that the proposed adaptive scheme has better performance for audio transmissions.

고속 핸드오버를 위한 PFMIPv6와 무선랜의 효율적인 연동 방안

As the number of a smart phone user over the world surprisingly grows and a wireless Internet market expands, service requirement of a mobile terminal is increasing. However, because there is no consideration of mobility in the early standard step, it is difficult to expect to improve the service performance in handover procedure. This paper proposes a PFMIPv6 handover scheme by using probe request message and authentication message and by using buffering scheme in IEEE 802.11. In addition, we simulated this proposal scheme and verified that the proposed handover scheme is improved in terms of handover delay, and average FTP throughput during the handover period.

An Adaptive Allocation Algorithm Using Directional CSMA/CA over mmWave Wireless Personal Area Networks

Directional antennas have the considerable benefits of higher antenna gain, long transmission distance and spatial reuse compared to omni-antennas. To support a directional antenna, IEEE 802.15.3c specifies a high data transmission rate and short frequency range communication based on the characteristics of 60GHz band. However, the contention-based protocol of IEEE 802.15.3c may cause channel collisions and throughput degradation as the number of stations in the network increases. In order to resolve this problem and reduce channel access latency, we propose an adaptive allocation algorithm in which the contention window size for optimal transmission probability is derived after the directional information has been obtained by means of AP control procedures. Extensive simulations demonstrate that the proposed algorithm outperforms the existing channel access scheme in IEEE 802.15.3c wireless personal area networks under different situations, especially when the number of contending stations is large.