In this paper, we focus on the resource scheduling of Long Term Evolution - Advanced (LTE-A) with Carrier Aggregation (CA). Application of CA meets the demand of bandwidth in LTE-A by aggregating several discrete carriers together. With different fading characters, the aggregated carriers have different coverage between each other. Considering the backward compatibility, there exist both LTE-A and LTE users. In order to improve the performance of LTE users and cell edge users, an improved proportional fair (PF) scheduling algorithm suitble to multi-carrier system is proposed. In this algorithm, a variable to limit the number of carriers each user can access is set, and a carrier weight factor which is composed of carrier coverage weight factor and user category weight factor is introduced. Simulation results show that the proposed algorithm can effectively improve the performance of cell edge users and LTE users.

A resource scheduling algorithm based on carrier weight in LTE-Advanced system with Carrier Aggregation

In LTE-A, efficient Physical Downlink Control Channel (PDCCH) scheduling is fundamental to ensuring not only users' Quality of Service (QoS) but also bursty data channels. However, the limited resource available for PDCCH has proven to be a major issue that hampers users' scheduling. By principle, every user equipment (UE) admitted into the network is expected to be scheduled by the control channel prior to gaining access to data channel's resources (i.e. Physical Resource Blocks-PRBs). However, the limited PDCCH resources in traditional systems usually result to some UEs being deprived from accessing PRBs because they have not been scheduled for resource access by PDCCH. This situation is a major connectivity challenge in LTE-A systems. As such, we have proposed a new remapping strategy for PDCCH resource scheduling based on linear transformation matrix. Our scheme remaps the users' search spaces using a transformation function derived from their previous search spaces and the available resources in order to efficiently address PDCCH resource utilization issue. Extensive simulation results show that our new scheme is able to reduce UEs' average blocking probability and as well improve PDCCH resource utilization. Notwithstanding this enhancement, our scheme still maintains the decoding procedure and search space concept in LTE-A systems. Terms — Physical downlink control channel (PDDCH), aggregation level, search space, control channel element, u ser equipment (UE).

http://www.jocm.us/uploadfile/2014/0731/20140731034027560.pdf

New Remapping Strategy for PDCCH Scheduling for LTE-Advanced Systems

Efficient resource utilization is of a high importance for LTE/LTE-A network performance and provisioning of user quality of experience. The eNodeB (LTE base station) is responsible for controlling the radio resources between the user and LTE /LTE-A network. The resources can be scheduled in two schemes; either independently or jointly by considering both uplink (UL) and downlink (DL) together. Joint scheduling is an attractive approach for resource utilization and for providing better Quality of Service (QoS), but it adds some computational complexity to the system. This paper aims to provide QoS-aware joint UL-DL scheduling for LTE-A utilizing the functionality of carrier aggregation. The scheme presented enforces the fair sharing of the resources between the UL and DL channels while maintaining good QoS. The work is based on simulation using the MATLAB-based IS-Wireless system level simulator. The key contributions of this work lie in addressing both the joint scheduling and the carrier aggregations while considering the QoS and traffic conditions of the users.

QoS-aware joint uplink-downlink scheduling in FDD LTE-Advanced with carrier aggregation

The number of mobile users is rapidly increasing. Therefore, the bandwidth demand of mobile users significantly growing. To answer users' demand, Carrier Aggregation is proposed in LTE systems. In Carrier Aggregation, communication between users and base stations are achieved by multi bands which have different coverage areas and mobile users can simultaneously connect one or multi carrier components in each band. Because of mobility of users and quality of carriers, the best available Carrier Components of each band should be assigned to each user in order to provide desired service to users. Several works have been proposed in the literature to address Carrier Components assignment methods in LTE systems by using Channel Quality Indicator, quality of service and service types. Although the previous works on carrier assignment methods significantly increase the performance of LTE system, continuously increasing bandwidth demand of users forces the operators to manage resource allocation more intelligently. Therefore, we have proposed a novel Carrier Component assignment method which considers user profiles and channel quality indicator to increase quality of services and experiences getting by mobile users. Results show that the proposed method uses system resources efficiently and can improve performance of LTE systems. Our method will help service providers build efficient carrier components assignment methods through considering user profile and performance metrics, such as band usage, throughput and delay.

/pdf/joint-and-partial-carrier-components-assignment-techniques-12afwh49sm.pdf

Joint and partial carrier components assignment techniques based on user profile in LTE systems

Long Term Evolution Advanced (LTE-A) is a promising technology to achieve peak data rate of up to 1 Gbit/s in the downlink and 500 Mbit/s in the uplink. Because adjacent cells employs the same frequency in universal frequency reuse scheme, interference between adjacent cells may degrade the bit rate, particularly at the cell edges. Inter-Cell Interference Coordination (ICIC) based on carrier aggregation as well as Coordinated Multipoint (CoMP) transmission and reception techniques have been considered as promising techniques to overcome the interference problem and to improve the bit rate at the cell edges. ICI problem can be mitigated by using different arrangements of frequency-bands allocations and possibly with different transmission power, distinguishing between the cell centre and the cell edge users. In this paper, mitigation of inter-cell interference using carrier aggregation (CA) and coordinated multipoint (CoMP) techniques are evaluated through computer simulaton. The simulation employs different frequency allocation schemes, fractional frequency reuse, different transmission powers, and different radio resource scheduling algorithms to evaluate and to enhance cell edge performance, bandwidth efficiency and throughput. The performance is evaluated in terms of SINR as a function of the number of femtocell users, and the separation distance from interfering cells. The performance is then compared between conventional technique, CA technique and the combined CA and CoMP techniques.

Xin-yang Ge

Papers

Resource scheduling in downlink LTE-advanced system with carrier aggregation