Scott Fowler

Analysis of adjustable and fixed DRX mechanism for power saving in LTE/LTE-Advanced

The 4G standard Long Term Evolution (LTE) has been developed for high-bandwidth mobile access for todays data-heavy applications, consequently, a better experience for the end user. To extend the user equipment battery lifetime, plus further support various services and large amount of data transmissions, the 3GPP standards for LTE/LTE-Advanced has adopted discontinuous reception (DRX). However, there is a need to optimize the DRX parameters, so as to maximize power saving without incurring network re-entry and packet delays. In this paper, we provide an overview of the fixed frame DRX cycle and compare it against an adjustable DRX cycle of the LTE/LTE-Advanced power saving mechanism, by modelling the system with bursty packet data traffic using a semi-Markov process. Based on the analytical model, we will show the trade-off relationship between the power saving and wake-up delay performance.

Local Load Balancing for Globally Efficient Routing in Wireless Sensor Networks

One of the limitations of wireless sensor nodes is their inherent limited energy resource. Besides maximizing the lifetime of the sensor node, it is preferable to distribute the energy dissipated throughout the wireless sensor network in order to minimize maintenance and maximize overall system performance. Any communication protocol that involves synchronization of peer nodes incurs some overhead for setting up the communication. We introduce a new algorithm, e3D (energy-efficient Distributed Dynamic Diffusion routing algorithm), and compare it to two other algorithms, namely directed, and random clustering communication. We take into account the setup costs and analyze the energy-efficiency and the useful lifetime of the system. In order to better understand the characteristics of each algorithm and how well e3D really performs, we also compare e3D with its optimum counterpart and an optimum clustering algorithm. The benefit of introducing these ideal algorithms is to show the upper bound on performance at the cost of astronomical prohibitive synchronization costs. We compare the algorithms in terms of system lifetime, power dissipation distribution, cost of synchronization, and simplicity of the algorithm. Our simulation results show that e3D performs comparable to its optimal counterpart while having significantly less overhead.

Study on power saving based on radio frame in LTE wireless communication system using DRX

Long Term Evolution (LTE) of 3GPP provides high bandwidth for data transfer. Having high bandwidth transfer will exhaust the user equipment (UE)s battery power quickly. To extend the UEs battery lifetime the 3GPP standards for LTE support Enhanced Discontinuous Reception (DRX). The DRX allow an idle UE to save battery by turning off the radio receiver for a predefined period. Since the Transmission Time Interval (TTI) is related to the size of the data block passed from the higher networks layers to the radio link layer, the DRX scheduler should vary the resource allocation of each user basis on TTI. In this paper, we have evaluated the influences of the TTI sizes as well as the effects of LTE DRX Light and Deep Sleep mode on power consumption for Voice and Web traffic.

QoE/QoS-aware LTE downlink scheduler for VoIP with power saving

The emerging and fastest growing multimedia services such as Skype, GTalk and interactive video gaming have created new challenges for wireless communication technologies, especially in terms of resource allocation and power optimization of User Equipments (UEs). The efficient resources and the power optimization are very important in the next communication systems because new multimedia services are more resource and power hungry. Having more traffic flow in the downlink as compared to the uplink, the resource allocation schemes in the downlink are more important than those in the uplink. In this paper, we have proposed a new downlink scheduling scheme, known as Quality-aware DRX (Q-DRX) Scheme, for Long Term Evaluation (LTE) wireless networks that not only improves the Quality of Service (QoS) to satisfy the user?s experience of multimedia services but also saves the UE?s power by using the Discontinuous Reception (DRX). This paper investigates how the different durations of DRX Light and Deep Sleep cycles affect the QoS and influence the Quality of Experience (QoE) of end users, in the context of Voice over IP (VoIP) traffic delivery over the LTE wireless network. The performance of the Q-DRX scheme is evaluated with traditional scheduling schemes, in the perception of the following important parameters, System Throughput, Throughput Fairness Index, Packet Loss Rate and Packet Delay. Our proposed Q-DRX Scheme successfully minimized the packet?s delay and packet?s loss by considering the key parameters of QoS with fair resources distribution among the UEs to achieve a high satisfaction level.

QoS-Aware LTE Downlink Scheduler for VoIP with Power Saving

The addition of emerging multimedia services such as Skype, GTalk, multi-user interactive gaming in cellular communication systems has created new challenges for resource allocation and power optimization. The requirement of efficient resource allocation is more important in downlink than uplink due to high traffic flows. These multimedia applications require more power, therefore power optimization has gained a key role in future communication systems. In this paper, a downlink scheduling technique in Long Term Evolution (LTE) is proposed that improves the Quality of Service (QoS) for multimedia services in relation with use of the power saving scheme at the User Equipment (UE) i.e. Discontinuous Reception (DRX). The DRX effectively improves power consumption at the cost of QoS degradation due to higher packet delays and packet losses. The proposed scheme considers key QoS parameters during scheduling with fair resource allocation while minimizing packet delay and packet loss even in a power saving environment.

Fast Handover over Micro-MPLS-Based Wireless Networks

Recently, there has been increasing interest in applying MPLS to IP-based wireless access networks [1]. During a handover on Mobile MPLS-based networks, a registration update message is sent from the Foreign Agent (FA) to the Home Agent (HA). This update message results in a handover delay because of the distance the registration update message must travel from the FA to the HA. To decrease frequent registration handover delays, a micro-mobility approach over MPLS-based networks (also known as Hierarchical Mobile MPLS (H-MPLS)) [2] method was proposed to overcome the limitations of the Mobile MPLS protocol. Studies have shown that with H-MPLS, the Mobile Node (MN) experiences considerably lower handover delays when compared with the delay incurred with conventional mobile MPLS [2], [3]. In this paper we propose to extend the use of H-MPLS by introducing Intermediate Label Information Base (I-LIB) on a Label Switching Router (LSR), which uses the MPLS forwarding and localized signaling. Our simulations demonstrate that with an I-LIB, the end-to-end delay is reduced as a result of a decrease in the handover latency during the establishment of a new Label Switched Path (LSP). With increasing usage of wireless devices supporting delay sensitive traffic (such as voice and video over IP), it is essential to provide lower end-to-end by minimizing handover delays since large delays cause Quality of Service (QoS) degradations.

Robust H.264/AVC Video Transmission using Data Partitioning and Unequal Loss Protection

In this work, we present an adaptive unequal loss protection (ULP) scheme for H264/AVC video transmission over lossy networks. This scheme combines erasure coding, H.264/AVC error resilience techniques and importance measures in video coding. The unequal importance of the video packets is identified in the group of pictures (GOP) and the H.264/AVC data partitioning levels. The presented method can adaptively assign unequal amount of forward error correction (FEC) parity across the video packets according to the network conditions, such as the available network bandwidth, packet loss rate and average packet burst loss length. A near optimal algorithm is developed to deal with the FEC assignment for optimization. The simulation results show that our scheme can effectively utilize network resources such as bandwidth, while improving the quality of the video transmission. In addition, the proposed ULP strategy ensures graceful degradation of the received video quality as the packet loss rate increases.

R^2NC: Redundant and Random Network Coding for H.264/SVC Transmission

In this paper we are interested in improving the performance of constructive network coding schemes for video transmission over packet lossy networks. A novel unequal packet loss protection scheme R2NC based on low-triangular global coding matrix with ladder-shaped partition will be presented, which combines redundant and random network coding for robust H.264/SVC video transmission. Firstly, the error-correcting capabilities of redundant network coding make our scheme resilient to loss. Secondly, the implementation of random network coding at the intermediate nodes with multiple input links can reduce the cost of network bandwidth, thus reducing the end to end delay for video transmission. Thirdly, the low-triangular global coding matrix with ladder-shaped partition is maintained throughout R2NC process to provide unequal erasure protection for H.264/SVC priority layers. The redundant network coding avoids the retransmission of lost packets and improves error correcting capabilities of lost packets. Based only on the knowledge of the loss rates on the output links, the source node and intermediate nodes can make decisions for redundant network coding and random network coding (i.e., how much redundancy to add at this node). However, the redundancy caused by redundant network coding makes the network load increases, in order to improve network throughput, we perform random network coding at the intermediate nodes. Our approach is grounded on the overall distortion of reconstructed video minimization by optimizing the amount of redundancy assigned to each layer. Experimental results are shown to demonstrate the significant improvement of H.264/SVC video reconstruction quality with R2NC over packet lossy networks.

Analytical evaluation of extended DRX with additional active cycles for light traffic

LTE and LTE-Advanced mobile technologies have integrated discontinuous reception (DRX) power saving method to optimize the power consumption at the user equipment (UE). The DRX method was proposed by the 3rd Generation Partnership Project (3GPP), and since then, the traffic behavior has been analyzed in several studies with a standard 3-state DRX model to describe the trade-off between power saving and delay. In this paper, we presented a novel 4-state and 5-state 3GPP LTE DRX mechanisms. The proposed mechanisms were developed by augmenting (an) active state(s) to deep and/or light sleep cycle of standard 3-state DRX for handling a small burst of packets, thereby bypassing the process of returning to the timer-dependent active mode. We have generated analytical models using a semi-Markov process for bursty packet data traffic and evaluated these augmented DRX mechanisms against a standard 3-state DRX method. Overall, the analytical results from varying timing parameters showed that our augmented DRX (both 4-state and 5-state) improved power saving factor (ranging between 1% and 8%) and reduced delay (ranging between 20% and 60%) compared to the standard 3-state DRX. Furthermore, the magnitude of improvement for both delay and power-saving was somewhat greater in 5-state than 4-state.

QoE Power-Efficient Multimedia Delivery Method for LTE-A

The fastest growing of multimedia services over future wireless communication systems demands more network resources, efficient delivery of multimedia service with high user satisfaction, and power optimization of user equipments (UEs). The resources and power optimization are significant in future mobile computing systems because emerging multimedia services consume more resources and power. The 4G standard of Long Term Evolution-Advanced (LTE-A) wireless system has adopted the discontinuous reception (DRX) method to extend and optimize the UE battery life, while there is no standard scheduling method to distribute the radio resources among the UE. This paper presents a downlink scheduler, i.e., Quality of Experience Power Efficient Method (QEPEM) for LTE-A, which efficiently allocates the radio resources and optimizes the use of UE power using the DRX mechanism. We investigate how the different duration of DRX Light and Deep Sleep cycle influences the Quality of Service (QoS) and QoE of end users, using voice over IP (VoIP) over the LTE-A. The QEPEM is evaluated with the traditional methods, in terms of system throughput, fairness index, packet loss rate, and packet delay. The QEPEM measures the users QoE and feeds back to the eNodeB for scheduling decisions along with other important parameters. Our proposed method reduces the packet delay and packet loss and increases the fairness and UE power saving with high user satisfaction.