Packet Data Services Research Articles

Comparative Study of Packet Scheduling Algorithm in LTE Network

At present, Long-Term Evolution (LTE) is the most popular Internet access technology because of its robust wireless connectivity that can support data, voice, video and messaging traffic. This advantage has significantly increased the number of users availing themselves of these services through various devices. Such an increase in the number of users has also increased network traffic. Thus, scheduling algorithms are needed to prioritize and distribute available resources among users to improve system performance. Researchers have proposed several algorithms that focus on meeting the Quality of Service requirement for different applications. The current study evaluates the performance of four scheduling algorithms for LTE downlink transmission, namely, proportional fair, exponential PF, exponential rule and log-rule algorithms, in a certain scenario. The performance of these algorithms was evaluated using an LTE-Sim simulator. Simulation results show that the log-rule algorithm outperforms other packet scheduling algorithms in terms of delay, throughput and packet loss ratio when serving Voice-over-Internet Protocol packet data service on the LTE network.

A novel geometric handover model for aerial 4G networks with WiFi‐based X2 interface

AbstractGiven the temporary nature of radio communications for mission critical scenarios, the existing dedicated public safety network lacks the flexibility of cutting edge technologies to leverage on packet data services. In this context, new challenges arise such as high‐capacity demand and low‐latency flexible backhaul connection for public safety users. In this paper, we consider a scenario in which 4G LTE radio coverage is provisioned by aerial eNodeBs installed on low‐altitude platforms raised in the sky and interconnected through WiFi links. We focus our attention on the critical aspect of theThird Generation Partnership Project handover mechanism studying the handover performance using a X2 interfaces over WiFi links. We develop a novel geometric model of the handover in the context of public safety communications but extensible also to other contexts. Relying on such a model, the handover failure probability is computed taking into account the different handover phases. The coverage area of an aerial eNodeB is studied using a suitable air‐to‐ground propagation model, while the average handover duration is computed taking into account the delay introduced by the WiFi communication dynamics. Copyright © 2016 John Wiley & Sons, Ltd.

Different Issues and Survey of Proposed Solutions in TCP over Wireless Environments

Abstract— Computer networks have experienced an explosive growth over the past few years, which has lead to some severe congestion problems. Reliable protocols like TCP works well in wired networks where loss occurs mostly because of congestion. However, in wireless networks, loss occurs because of bit rates and handoffs too. TCP responds all losses by congestion control and avoidance algorithms, which results in degradation of TCP’s End-To-End performance in wireless networks. This paper discusses different issues and problems regarding use of TCP in wireless networks and provides comprehensive survey of various schemes to improve performance of TCP in Wireless Networks. Keywords—TCP, Mobile-IP, Wireless networks, Protocol design. I. INTRODUCTION Due to rapid advances in the area of wireless communications and the popularity of the Internet, the provision of packet data services for applications like e-mail, web browsing, mobile computing etc. over wireless is gaining importance. The TCP/IP protocol suites have number of layers, of which transport layer is used widely for mobility. It uses protocols like TCP and UDP for transferring data. While coming towards wireless environment, we must understand what wireless environment is first. Wireless environment can be broadly distinguished in three types: Cellular networks, Ad-hoc networks and Satellite networks. In Cellular Networks a mobile host is connected to the fixed network with the help of the Base Station. This is the most common form of Wireless Network currently in use. Mobile devices like cell phones, laptops use this network. Most of the proposed solutions to TCP use this model. All service providers are on the fixed network and hence we have to address the problem of wireless networks only at one end point. Ad – Hoc Networks are formed by mobile hosts which are connected to each other within a radio distance. This kind of a model is not well deployed and very few solutions have been proposed to this model. Satellite Networks are those where a satellite link is in between the sender and the receiver. These have very high BERs (Bit Error Rates) and high latency because the Satellite are at a great distance from the surface. Now going towards our main concept, Transmission Control Protocol (TCP) [1] is one of the important standards in the internet world and also a very vital element in internet protocol suite. It provides a connection oriented service with reliable data transfer over the unreliable underlying protocols. It uses sequence numbering and timers to ensure reliable transfer of packets. TCP's flow control increases the data sending rate until there are signs of congestion in the network. The basis of TCP congestion control lies in the following algorithms: slow start, congestion, avoidance, fast retransmit and fast recovery [2]. In the following we first outline the different issues of TCP in wireless networks. Then the main problem regarding TCP. Then we summarize some proposed solutions with their strengths and weaknesses. II. I

Energy Efficient Packet Data Service in Wireless Sensor Network in Presence of Rayleigh Fading

Energy level performances of three packet delivery schemes in Wireless Sensor Networks (WSN) are evaluated in presence of Rayleigh fading. Three different information delivery mechanisms are investigated using regenerative relays with or without error correction capability. Energy consumption for successful delivery of a data packet for each mechanism is evaluated and compared under several conditions of node density, bit rate, transmit power, and channel fading. Energy efficiencies of different retransmission schemes are also evaluated. Further, an optimal packet length based on energy efficiency is derived. Impact of optimal packet size on average number of retransmission and total energy expenditure is analyzed for each delivery scheme.

A data flow optimization method for high speed MAC processing in an IEEE 802.16m modem

IEEE 802.16m technology is expected to provide high speed packet data service over wireless. Due to the large amount of data to be processed over a short period of time, an efficient MAC processing in the modem is crucial. Since the MAC processing algorithm has optimization limitations, we focus on a data flow optimization in the system level design, so that the number of external memory accesses is minimized. Experimental results show that our approach results in an up to sixteen times faster IEEE 802.16m modem system.

Performance evaluation of mobile DAB receivers in enhanced packet mode

This paper describes the bit error rate (BER) performance of the Enhanced Packet Mode (EPM) of the Eureka 147 Digital Audio Broadcast (DAB) system in a mobile environment. The BER performance of DAB-EPM is characterized by computer simulations in frequency selective (typical case) and flat faded (worst case) mobile channels. For each of these channels, simulations are performed at vehicle speeds ranging from very slow (walking speed) to very fast (high speed trains). Simulation results show that, in typical frequency selective mobile environments, the target BER of 10 8 required to deliver adequate packet data service via the EPM is achieved at Carrier to Noise Ratio (C/N) values smaller than the target value of 14 dB used in coverage and frequency planning at most of the vehicle speeds tested. Moreover, the coverage area of packet data services is equivalent to the coverage of audio services delivered with the MPEG Layer 2 audio codec and the Unequal Error Protection Level 3 of DAB.

Analysis of Heuristic Graph Partitioning Methods for the Assignment of Packet Control Units in GERAN

Over the last few years, graph partitioning has been recognized as a suitable technique for optimizing cellular network structure. For example, in a recent paper, the authors proposed a classical graph partitioning algorithm to optimize the assignment of cells to Packet Control Units (PCUs) in GSM-EDGE Radio Access Network. Based on this approach, the quality of packet data services in a live environment was increased by reducing the number of cell re-selections between different PCUs. To learn more about the potential of graph partitioning in cellular networks, in this paper, a more sophisticated, yet computationally efficient, partitioning algorithm is proposed for the same problem. The new method combines multi-level refinement and adaptive multi-start techniques with algorithms to ensure the connectivity between cells under the same PCU. Performance assessment is based on an extensive set of graphs constructed with data taken from a live network. During the tests, the new method is compared with classical graph partitioning approaches. Results show that the proposed method outperforms classical approaches in terms of solution quality at the expense of a slight increase in computing time, while providing solutions that are easier to check by the network operator.

Performance analysis for hierarchical resource allocation in multiplexed mobile packet data networks

The general packet radio service (GPRS) can be thought of as an overlay network above a Global Systems for Mobile (GSM) network. In cooperation with the GSM system, GPRS supports both voice and packet data services. Obviously, combining voice and data traffic implies the nature of contending with finite radio resources. The paper focuses on voice/data integrated GPRS downlink traffic and proposes two hierarchical resource allocation strategies by considering time slots and radio blocks simultaneously with two different TDMA frame configurations. The radio block based resource allocation can characterize the multiplexing scheme of the practical GPRS operation. The performance of the proposed strategies were evaluated analytically by multidimensional Markov chain and verified through intensive computer simulations. Based on both the analytical and simulation results, it showed that the proposed allocation strategies can offer high utilization of transmission resource, as well as low blocking probability to GPRS users. The results of the study provide not only a practical thinking for implementation but also a guideline for analysis.

Transmit Diversity Schemes for BCH Transmission in IEEE 802.16m

IEEE802.16m standard is based on the MIMO-OFDM technology to provide high speed packet data service both in downlink and uplink. For the downlink broadcasting of control information, in order to extend the coverage of a cell, the nominal operating point should be set for the user at the edge of a cell, and no feedback should be used. For broadcasting that information, the MIMO technology should take a transmit diversity form targeted for low SNR. Several transmit diversity schemes are presented and preferable modes of operations for the broadcasting channel are proposed with numerical analysis.

Throughput Performance of MC-CDMA HARQ Using ICI Cancellation

Multi-carrier code division multiple access (MC-CDMA) is a promising wireless access technique for the next generation mobile communications systems, in which broadband packet data services will dominate. Hybrid automatic repeat request (HARQ) is an indispensable error control technique for high quality packet data transmission. The HARQ throughput performance of multi-code MC-CDMA degrades due to the presence of residual inter-code interference (ICI) after frequency-domain equalization (FDE). To reduce the residual ICI and improve the throughput performance, a frequency-domain soft interference cancellation (FDSIC) technique can be applied. An important issue is the generation of accurate residual ICI replica for FDSIC. In this paper, low-density parity-check coded (LDPC-coded) MC-CDMA HARQ is considered. We generate the residual ICI replica from a-posteriori log-likelihood ratio (LLR) of LDPC decoder output and evaluate, by computer simulation, the throughput performance in a frequency-selective Rayleigh fading channel. We show that if the residual ICI is removed, MC-CDMA can provide a throughput performance superior to orthogonal frequency division multiplexing (OFDM).

Comparative Analysis of Energy-Saving Techniques in 3GPP and 3GPP2 Systems

Energy conservation is essential to wireless networks, particularly for third-generation (3G) and fourth-generation (4G) wireless systems, because high-speed data transmissions would rapidly exhaust the energy of a mobile station. This paper presents the details of energy-saving mechanisms for packet data services in two major standards, namely, the Third-Generation Partnership Project (3GPP) and the Third-Generation Partnership Project 2 (3GPP2). In addition to qualitative comparison, analytic models and quantitative comparison based on the energy-saving models are provided. The proposed analytic models analyze and quantify the energy consumption for bursty and streaming traffic in cdma2000 and wideband code division multiple access (WCDMA). The impacts of an inactivity timer on <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">energy</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">consumption</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">and</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reconnection</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cost</i> are demonstrated further by simulation and analysis. The analytic results could be used to suggest proper timer lengths that can balance the energy consumption and the reconnection cost. In addition to providing insights of the energy-conservation mechanisms of 3GPP and 3GPP2, which are often difficult to directly obtain from standards specifications, results shown in this paper are also practical for 3GPP and 3GPP2 operators to determine proper parameters for energy efficiency.

Link adaptation algorithms for improved delivery of delay- and error-sensitive packet-data services over wireless networks

Link Adaptation is a radio resource management technique that assesses the channel conditions and selects a transport mode, from a set of possible options, which is optimised for these conditions according to a predefined criterion. The optimum transport mode is commonly determined so as to maximise the throughput. Although this approach may be appropriate for best-effort services, its suitability for multimedia services, usually characterised by tight delay and error performance constraints, has been questioned. As a result, a number of alternative algorithms have been proposed in the literature. In this context, this paper presents and evaluates in a dynamic radio environment several Link Adaptation algorithms designed to enhance the provision of delay- and error-sensitive multimedia packet-data services over wireless systems. The obtained results demonstrate that significant improvements in terms of throughput, transmission delay, error performance and operation of Link Adaptation itself can be obtained with the proposed schemes.

A Delay-Centric Dynamic Resource Allocation Algorithm for Wireless Communication Systems Based on HNN

This paper proposes a dynamic resource-allocation (DRA) algorithm for packet data services in wireless communication systems based on Hopfleld neural networks (HNNs). The resource-allocation algorithm assumes a delay-centric approach in that it maximizes resource utilization of the overall system while minimizing the packet delay. The real-time (RT) working capability of HNN hardware implementation means that a very powerful scheduling DRA algorithm can be obtained. A generic formulation of the algorithm is presented to establish the optimal bit rate allocation. In addition, some illustrative examples of this formulation are given, considering specific wireless communication systems, such as general packet radio service (GPRS) or universal mobile telecommunications system (UMTS). To be more precise, the performance of the proposed DRA algorithm is evaluated in a realistic UMTS scenario, considering both RT and nonreal-time (NRT) services. To obtain the best resource distribution and fulfill the different quality-of-service (QoS) levels required by RT and NRT services, the new HNN-based delay-centric DRA algorithm is performed twice. Initially, only the RT services are considered, and following this, all the NRT services are taken into account. The results reveal that the proposed DRA algorithm outperforms other reference algorithms in terms of not only average packet delay but the allocated total bit rate as well.

Cross-layer Optimized Vertical Handover Schemes between Mobile WiMAX and 3G Networks

Nowadays, wireless packet data services are provided over Wireless MAN (WMAN) at a high data service rate, while 3G cellular networks provide wide-area coverage at a low data service rate. The integration of mobile WiMAX and 3G networks is essential, to serve users requiring both high-speed wireless access as well as wide-area connectivity. In this paper, we propose a cross-layer optimization scheme for a vertical handover between mobile WiMAX and 3G cellular networks. More specifically, L2 (layer 2) and L3 (layer 3) signaling messages for a vertical handover are analyzed and reordered/combined, to optimize the handover procedure. Extensive simulations using ns-2 demonstrate that the proposed scheme enhances the performance of a vertical handover between mobile WiMAX and 3G networks: low handover latency, high TCP throughput, and low UDP packet loss ratio.

Combined Effect of Random Transmit Power Control and Inter-Path Interference Cancellation on DS-CDMA Packet Mobile Communications

In mobile communication systems, high speed packet data services are demanded. In the high speed data transmission, throughput degrades severely due to severe inter-path interference (IPI). Recently, we proposed a random transmit power control (TPC) to increase the uplink throughput of DS-CDMA packet mobile communications. In this paper, we apply IPI cancellation in addition to the random TPC. We derive the numerical expression of the received signal-to-interference plus noise power ratio (SINR) and introduce IPI cancellation factor. We also derive the numerical expression of system throughput when IPI is cancelled ideally to compare with the Monte Carlo numerically evaluated system throughput. Then we evaluate, by Monte-Carlo numerical computation method, the combined effect of random TPC and IPI cancellation on the uplink throughput of DS-CDMA packet mobile communications.

IP Transmission over TETRA Packet Data Service: Simulation and Measurement Results

This paper evaluates the packet data performance of Internet Protocol (IP) over TErrestrial Trunked RAdio (TETRA), focusing on the effects of packet size and message transmission rate. We performed a range of simulations to evaluate the average packet delay and packet failure probability corresponding to IP datagram transmission on the Packet Data CHannel (PDCH) in a TETRA cell. We employed IP packets of different sizes and we considered a number of different scenarios with respect to the number of users in a cell and datagram transmission rate. The simulation results offer TETRA operators the means for facilitating network planning and optimization of datagram-based services. Apart from the simulation, we also conducted an extensive measurement survey on the performance of IP over the TETRA PDCH. In particular, we carried out measurements in a client---server communication scenario with different datagram sizes and typical user mobility and radio propagation conditions. Measurement results include throughput, delay jitter, percentage of lost datagrams and out-of-order datagrams. The results obtained through our measurement survey can extent and enhance the simulation results because they are more realistic and consider user mobility as well as channel impairments.

Coordinated load balancing, handoff/cell-site selection, and scheduling in multi-cell packet data systems

We investigate a wireless system of multiple cells, each having a downlink shared channel in support of high-speed packet data services. In practice, such a system consists of hierarchically organi...

Privileged Treatment of UMTS Subscribers in GSM Networks

Different user segments have various requirements and expectations towards the performance of mobile networks. Subscribers having experienced the high quality of UMTS networks desire to maintain high speech quality and excellent data throughput also in areas of missing UMTS but existing GSM coverage. In GSM networks a privileged treatment of UMTS subscribers by means of proper resource allocation provides a substantial quality improvement with respect to standard GSM subscribers. This strategy allows network operators to reduce the performance gap between both network areas experienced by UMTS subscribers. A detailed study on the performance of circuit switched speech and packet data services has been performed based on system level simulations. The results show significant speech quality advantages for users with dual-RAT terminals compared to standard GSM users as well as notably higher data throughput rates.

Broadcast Approach for UMTS Mobility Database Recovery

The universal mobile telecommunications system (UMTS) provides high bandwidth packet data services to mobile users. To support mobility management, an MM context is established for every mobile station in its corresponding serving GPRS support node (SGSN). When the SGSN fails, all MM contexts in the SGSN are corrupted. These MM contexts must be recovered or data delivery to the mobile stations will fail. This paper describes a broadcast approach that allows the MS to detect lost MM context in SGSN and therefore speeds up the process for SGSN recovery. We propose an analytic model to evaluate the performance of the broadcast approach. The analytic model is validated against simulation experiments. Based on our study, the network operator can select the appropriate parameter values in the broadcast approach for various traffic conditions.

Performance of High-Speed Downlink Packet Access in Coexistence With Dedicated Channels

The joint third-generation system performance of high-speed downlink packet access (HSDPA) and Release 99 (Rel'99) dedicated channels (DCH) is studied. Given such a scenario, the optimal sharing of the cell carrier transmit power between HSDPA and DCH, which is conditioned on a certain number of channelization codes that are reserved for HSDPA transmission, is addressed. Detailed network-performance results are shown from a comprehensive dynamic system-level simulator, which includes a simulation of many cells and users, and a detailed modeling of layer 1 to layer 3. Compared to a scenario without HSDPA, the total cell throughput can be increased by 69% by allocating five high-speed physical downlink shared channel codes and 35% of the maximum cell transmit power to HSDPA transmission. These results are obtained for a macrocellular scenario with best effort packet data services. Furthermore, it is demonstrated that part of this capacity gain comes from better utilization of the available cell transmit power since less power control headroom must be reserved for HSDPA. The presented performance results reflect the expected performance improvement from gradually introducing HSDPA in an existing Rel'99 wideband code-division multiple-access network