Huda Adibah Mohd Ramli

Performance of well known packet scheduling algorithms in the downlink 3GPP LTE system

This paper investigates the performance of well known packet scheduling algorithms developed for single carrier wireless systems from a real time video streaming perspective. The performance evaluation is conducted using the downlink third generation partnership project long term evolution (3GPP LTE) system as the simulation platform. This paper contributes to the identification of a suitable packet scheduling algorithm for use in the downlink 3GPP LTE system supporting video streaming services. Simulation results show that, in the downlink 3GPP LTE system supporting video streaming services, maximum-largest weighted delay first (M-LWDF) algorithm outperforms other packet scheduling algorithms by providing a higher system throughput, supporting a higher number of users and guaranteeing fairness at a satisfactory level.

Delay-Prioritized Scheduling (DPS) for Real Time Traffic in 3GPP LTE System

Given that the co-existence of multimedia applications will be a norm in the future wireless systems, their quality of service (QoS) requirements need to be guaranteed. This has imposed new challenges in the design of packet scheduling algorithms in these systems. To address those challenges, a new packet scheduling algorithm for real time (RT) traffic in downlink third generation partnership project long term evolution (3GPP LTE) system is proposed in this paper. The proposed algorithm utilizes each users packet delay information and its instantaneous downlink channel conditions when making scheduling decisions. Simulation results show that the proposed algorithm outperforms opportunistic scheduling and maximum-largest weighted delay first algorithms by maximizing system throughput and satisfying the QoS requirements of the RT traffic.

Impact of CQI feedback rate/delay on scheduling video streaming services in LTE downlink

The major attraction of the next generation wireless systems such as the third generation partnership project (3GPP) Long Term Evolution (LTE) is the availability of high data-rate video services at high user velocities. However, it is quite a challenge to provide the required level of quality of service (QoS) and maintain the planned system performance due to limited radio resources, unreliable radio propagation channel and high user demands. This paper analyses the impact of channel quality indicator (CQI) delay and its aperiodic reporting rate on the performance of a well known scheduling algorithm serving video streaming users at different velocities. The analysis will be compared against the system having perfect and delayed channel knowledge at each scheduling instance. We then recommend the minimum rate requirement of aperiodic CQI reports to maintain the required QoS for a certain number of video streaming users.

OPTIMIZED PERFORMANCE EVALUATION OF LTE HARD HANDOVER ALGORITHM WITH AVERAGE RSRP CONSTRAINT

Hard handover mechanism is adopted to be used in 3GPP Long Term Evolution (3GPP LTE) in order to reduce the complexity of the LTE network architecture. This mechanism comes with degradation in system throughput as well as a higher system delay. This paper proposes a new handover algorithm known as LTE Hard Handover Algorithm with Average Received Signal Reference Power (RSRP) Constraint (LHHAARC) in order to minimize number of handovers and the system delay as well as maximize the system throughput. An optimized system performance of the LHHAARC is evaluated and compared with three well-known handover algorithms via computer simulation. The simulation results show that the LHHAARC outperforms three well-known handover algorithms by having less number of average handovers per UE per second, shorter total system delay whilst maintaining a higher total system throughput.

Optimization of handover algorithms in 3GPP long term evolution system

Handover in LTE is purely hard handover. The use of break-before-connect handovers reduces the complexity of the LTE network architecture. However, the hard handover may result in data being lost. A Handover algorithm is needed for making handover decision. This decision may vary over time, depending on users mobility. Many handover algorithms have been proposed. In this work, we optimized three well known handover algorithms in the LTE system. Simulation results show that this optimization outperforms non-optimized algorithms by minimizing the average number of handovers per UE per second while maximizing average system throughput.

Resource allocation technique for video streaming applications in the LTE system

Long term evolution (LTE) is the next generation wireless system that supports all IP transmission for multimedia services. The quality of service (QoS) requirements of multimedia services are one of the major challenges that need to be addressed by packet scheduling in the LTE system. This paper proposes a new resource allocation technique for real time (RT) video streaming applications in the downlink LTE system. Resource allocation, which is one of packet scheduling techniques, utilizes instantaneous downlink signal to noise ratio (SNR), packet delay and buffer information when determining the amount of radio resources to be allocated to a user. Simulation results show that the proposed technique outperforms opportunistic technique, a resource allocation technique discussed in the literature, by maximizing system throughput, efficiently utilizing the available radio resources and satisfying the QoS requirements of RT video streaming applications at a higher number of users.

Modeling and simulation of packet scheduling in the downlink long term evolution system

Long term evolution (LTE) is the next generation wireless system that uses orthogonal frequency division multiple access (OFDMA) technology in the downlink. Packet scheduling becomes paramount as the wireless systems are moving towards all IP transmissions. Since LTE system is relatively new, very little work has been published to date that can precisely model and simulate the downlink LTE system environment. This paper provides detailed descriptions on modeling and simulation of packet scheduling in the downlink LTE system using a C++ simulation tool. The tool accurately modeled the wireless system parameters and can be used for study of optimization of the LTE system.

Requirement of Handover Modeling in the Downlink 3GPP Long Term Evolution System

Long Term Evolution (LTE) is the next generation wireless system that uses Break-before-Connect technology in the handover scheme, unlike handover in the Wide-band Code Division Multiple Access (WCDMA) that uses Connect-before-Break technology. In the LTE system, handover is one of the important radio resource management schemes that are responsible for mobility of user equipments, load balancing and interference management. This paper provides detailed description on requirements involved for handover procedure in the LTE system and the feasibility to extend the current software simulation tool of the LTE system to support multiple cells for handover. This paper contributes to the identification of the requirements and specifications that are needed for further study of handover procedure in the LTE system.

HARQ aware scheduling algorithm for the downlink LTE system

To ensure an efficient and reliable data transmission over the error-prone downlink long term evolution (LTE) system, packet scheduling is tightly-coupled with adaptive modulation and coding (AMC) scheme and hybrid automatic repeat request (HARQ) process. Most of the packet scheduling algorithms proposed in the literature either fail to incorporate HARQ, or even if they do, these algorithms are not suited for delay sensitive guaranteed bit rate (GBR) services. A new packet scheduling algorithm that prioritizes HARQ users is proposed in this paper to support a delay sensitive GBR service. Simulation results show that this algorithm outperforms modified-largest weighted delay first (M-LWDF) algorithm by minimizing the number of lost packets, maintaining a low queuing delay and maximizing effective user throughput.

Robust scheduling algorithm for guaranteed bit rate services

This paper proposes a novel packet scheduling algorithm to overcome detrimental effects of channel impairments on the quality of service of delay-sensitive Guaranteed Bit Rate (GBR) services. The proposed algorithm prioritises the packets that require retransmission of Hybrid Automatic Repeat Request (HARQ) users compared to the packets of new users. The packets of new users are scheduled according to the Channel Quality Information (CQI), average throughput and packet delay information. Computer simulations have demonstrated that the proposed algorithm has 22.7% system capacity improvement over a well-known algorithm. It also tolerates for up to 200% delay of CQI and reduces the uplink signalling overhead by 150% compared to the well-known algorithm without compromising the quality of service requirements of the GBR services.