Salman A. AlQahtani

Performance Modeling and Evaluation of Novel Scheduling Algorithm for LTE Networks

Long Term Evolution (LTE) packet scheduling plays an essential role as part of LTEs Radio Resource Management (RRM) to support successful implementation of new data services across the LTE network. The main contribution of this paper is to model and propose a novel scheduling scheme for LTE networks and to compare its performance with the performances of both the Best-CQI and RR Uplink schedulers. The Best-CQI scheduler is characterized by high data rates at cell level, but poor fairness. On the other hand, the round robin (RR) scheduler is characterized by low data rates at cell level, but good fairness. The main goal of our proposed scheme is to process these two conflicts terms in a better way. Performance modeling results presented in the paper show that the newly proposed scheduling scheme allows fair distribution of available LTE resources while at the same time keeps the systems capacity utilization as good as possible.

Comparing different LTE scheduling schemes

Long Term Evolution (LTE) is a cellular technology developed to support diversity of data traffic at potentially high rates. 3GPPs LTE is defined by the standardization bodys Release 8 and 9. A key mechanism in the LTE traffic handling is the packet scheduler, which is in charge of allocating resources to active flows in both the frequency and time dimension. The scheduling scheme used largely impacts the throughput of individual users as well as throughput of the cell. It is worthwhile to evaluate the throughput and fairness conditions for different scheduling schemes before the actual deployment of LTE scheduler. Our main contribution in this study is to evaluate and compare the performance of six scheduling schemes designed for LTE network in terms of users throughput and fairness. The findings from our performance evaluation presented to draw conclusions on the performance of the six schedulers, and point out the strengths and weakness that are common to schedulers under study. This would help design the scheme of the scheduler at the eNodeB appropriately.

Dynamic radio resource allocation for 3G and beyond mobile wireless networks

Next generation of wireless cellular networks aim at supporting a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Resource allocation and call admission control (CAC) are key management functions in future 3G and 4G cellular networks, in order to provide multimedia applications to mobile users with QoS guarantees and efficient resource utilization. There are two main strategies for radio resource allocations in cellular wireless networks known as complete partitioning (CP) and complete sharing (CS). In this paper, theses strategies are extended for operation in 3G and beyond network. First, two CS-based call admission controls, referred to herein as queuing priority call admission control (QP-CAC) and hybrid priority call admission control (HP-CAC), and one CP-based call admission control referred to as complete partitioning call admission control (CP-CAC) are presented. Then, this study proposes a novel dynamic procedure, referred to as the dynamic prioritized uplink call admission control (DP-CAC) designed to overcome the shortcomings of CS and CP-based CACs. Results indicate the superiority of DP-CAC as it is able to achieve a better balance between system utilization, revenue, and quality of service provisioning. CS-based algorithms achieve the best system utilization and revenue at the expense of serious unfairness for the traffic classes with diverse QoS requirements. DP-CAC manages to attain equal system utilization and revenue to CS-based algorithms without the drawbacks in terms of fairness and service differentiation.

Adaptive rate scheduling for 3G networks with shared resources using the generalized processor sharing performance model

In current and next 3G and beyond wideband code-division with multiple access (WCDMA) cellular networks, sharing the radio access network has become an important issue for 3G mobile operators. 3G and beyond network rollout is a very costly and time consuming process. Therefore, sharing of network infrastructure among operators offers an alternative solution to reducing the investment in the coverage phase of WCDMA. In radio access network (RAN) sharing method, which is our focus in this study, each operator has its own core network and only the RAN is shared. It implies that multiple operators fully share the same RAN. Without an efficient RRM, one operator can exhausts the capacity of others. This study tackles an efficient scheduling to provide maximum system throughput and proportional fairness in accordance with operator capacity share through adaptive resource allocation scheme. We refer to this new scheme as Multi-operators Code Division Generalized Processor sharing scheme (M-CDGPS). It employs both adaptive rate allocation to maximize the resource utilization and GPS techniques to provide fair services for each operator. The performance analysis in terms of bounded delay and queue size are obtained.

Performance analysis of two throughput-based call admission control schemes for 3G WCDMA wireless networks supporting multiservices

The wide-band code division multiple access (WCDMA) based 3G and beyond cellular mobile wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Call admission control is a very important measure in WCDMA system to guarantee the quality of the communicating links. Two throughput-based admission control strategy with multi-services, referred to herein as the complete partitioning CAC (CP-CAC) and the queuing priority CAC (QP-CAC), supporting real-time (RT) and non-real-time (NRT) services are analyzed and compared. The main contribution of this paper is the development of an analytical model for the QP-CAC algorithm which can be easily extended and used for CP-CAC. Furthermore, our analysis relaxes the typically used assumptions of equal channel holding time and equal resource usage for RT and NRT calls. More importantly, the analytical model covers the case when each traffic class has different requirements in terms of bandwidth, buffer size, average channel holding time, average time out, and Eb/No requirements. We also develop a simulation tool to test and verify our results. Finally, we present numerical examples to demonstrate the performance of the proposed CAC algorithms and we show that analytical and simulation results are in total agreement.

Uplink Call Admission Schemes for 3G and Beyond Mobiles Wireless Networks Supporting Heterogeneous Traffic

The wide-band code division multiple access (WCDMA) based 3G and beyond cellular mobile wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Soft capacity is one of the main characteristics of these networks and it necessitates new radio resource management strategies to serve diverse quality of service requirements. In this paper, resource sharing methods known as complete sharing (CS) based call admission controls and complete partitioning (CP) based call admission control are extended for operation in 3G WCDMA network. The extension includes devising call admission control with the deployment of buffering and threshold concepts. Two CS based call admission controls, referred to herein as queuing priority call admission control (QP-CAC) and hybrid priority call admission control (HP-CAC), and one CP based call admission control referred to herein as complete partitioning call admission control (CP-CAC) are presented. All proposed schemes support multiple admission priority classes based on request types (newly originating calls and handoff requests) and the traffic class (real-time and non real-time). CS based algorithms achieve the best system utilization at the expense of unfairness for the traffic classes with diverse QoS requirements while the CP-CAC ensure the fairness and service differentiation

Adaptive Radio Resource Management for Multi-Operator WCDMA Based Cellular Wireless Networks with Heterogeneous Traffic

In current and next 3G and beyond mobile wireless systems, sharing the radio access network has become an important issue for 3G mobile operators. Sharing network infrastructure amongst operators offers an alternative solution to reduce the investment in the coverage phase of WCDMA, allows increased coverage, reduces time to market, and allows earlier user acceptance for WCDMA and its related services. In this paper a novel radio resource management strategy known as adaptive partitioning with borrowing (APB) is proposed to cope with the implied new architectural changes. This strategy is devoted to achieve an efficient usage of the available pool of radio resources while satisfying the required quality of service (QoS) in heterogeneous traffic 3G wireless networks. Grade of service (GoS) and resources utilization are considered in this study to evaluate the network performance. Simulation results indicate that the proposed APB resource allocation provides higher resource utilization under all load conditions leading in turn to increased revenue. Moreover it provides the best balance between the system utilization and the required QoS

A QoS-Aware call admission control algorithm for 3G cellular wireless networks

The 3G cellular mobile systems which are based on WCDMA technology are expected to be interference limited. Soft capacity is one of the main characteristics of 3G (i.e, UMTS) and it requires new radio resource management strategies to serve diverse quality of service requirements. In this paper, a WCDMA prioritized uplink call admission control (CAC) algorithm for UMTS, which combines QoS negotiation and service differentiation by priority, is studied. This CAC scheme gives preferential treatment to high priority calls, such as soft handoff calls, by reserving some bandwidth margin (soft guard channel) to reduce handoff failures. In addition, queuing is also used to enhance the handoff success probability. The algorithm uses the effective load as an admission criterion and applies different thresholds for new and handoff calls. Finally, the study considers two types of services: voice and data calls. Results indicate that this algorithm reduces the drop handoff calls and increases the total system capacity; hence the GoS and the system performance can significantly be improved especially in case of high mobility environments.

A Prioritized Uplink Call Admission Control Algorithm for 3G WCDMA Cellular Systems with Multi-Services

The 3G cellular mobile systems which are based on WCDMA technology are expected to be interference limited. Soft capacity is one of the main characteristics of 3G (i.e, UMTS) and it requires new radio resource management strategies to serve diverse quality of service requirements. In this paper, a WCDMA prioritized uplink call admission control (CAC) algorithm for UMTS, which combines QoS negotiation and service differentiation by priority, is studied. This CAC scheme gives preferential treatment to high priority calls, such as soft handoff calls, by reserving some bandwidth margin (soft guard channel) to reduce handoff failures. In addition, queuing is also used to enhance the handoff success probability. The algorithm uses the effective load as an admission criterion and applies different thresholds for new and handoff calls. Finally, the study considers two types of services: voice and data calls. Results indicate that this algorithm reduces the drop handoff calls and increases the total system capacity; hence the GoS and the system performance can significantly be improved especially in case of high mobility environments.

Packet Reservation Multiple Access (PRMA) with Random Contention

Packet reservation multiple access (PRMA) can be considered as a merge of slotted ALOHA protocol and time division multiple access (TDMA) protocol. Independent terminals transmit packets to base station by contending to access an available time slots. A terminal that succeeds in reserving a certain time slot keeps on this reservation for transmitting its subsequent packets. Speech activity detection is used in PRMA to improve system capacity. In this work we propose a simpler contention mechanism that does not depend on a predetermined permission probability as in the original PRMA. In the new method, terminals select the contention slot uniformly from the pool of remaining free slots in the current frame. We evaluate the performance of the new contention mechanism in terms of various metrics including maximum number of carried voice calls and packet delays for a given acceptable drop rate of voice packets. We show that the new mechanism is superior to that of the original PRMA for loaded systems and is expected to be insensitive for traffic source burstiness.