Guillermo Galaviz

On a Spectrum Resource Organization Strategy for Scheduling Time Reduction in Carrier Aggregated Systems

In this letter we develop an efficient method to reduce the scheduling delay in Carrier Aggregated systems. We will show that it is possible to reduce scheduling delay by organizing available resource blocks in sets. A Resource Block Organization Algorithm is designed and evaluated through simulation in a macrocellular environment. Results show that the achievable scheduling delay reduction depends on the average number of resource blocks required per user. For the specific evaluation conditions the scheduling delay due to resource assignment can be reduced on average from 4 to 8 times when compared to block by block scheduling.

A resource block organization strategy for scheduling in carrier aggregated systems

Carrier aggregation (CA) is a promising technology that will allow IMT-Advanced system candidates to achieve spectrum bandwidths of up to 100 MHz using available system resource blocks (RB), even if these are fragmented. Implementation of CA functionality is managed through the use of schedulers capable of assigning multiple RBs to a user. When each available RB is handled individually, the delay from assigning multiple RBs to each user can affect the quality of service (QoS). In this article we develop an efficient scheduling strategy to reduce spectrum resource assignment delay in systems that make use of CA. This strategy is based on an a-priory organization of available RBs in sets. Two different RB Organization Algorithms are compared. In order to evaluate the performance of the proposed strategy numerical simulation was performed using a Round Robin scheduler for the downlink of a macro-cellular environment. Results show that using the proposed strategy it is possible to reduce the delay required to assign resources to users without affecting the downlink user capacity when compared to block by block scheduling strategies proposed in literature. The benefits of using the proposed strategy are discussed as well as improvement opportunities.

Evaluation of Scheduling Algorithms for 5G Mobile Systems

One of the key elements of the fifth generation (5G) of mobile communication systems is the support of a large number of users communicating through a wide range of devices and applications. These conditions give rise to heterogeneous traffic offered to the network. In order to carry such traffic in a wireless network, the design and development of schedulers capable of considering the conditions of each user is needed. In this chapter a Model Based Design (MBD) and Model Based Testing (MBT) approach are used to implement and evaluate different scheduling algorithms that consider the Quality of Service (QoS) requirements of each user as well as the individual channel conditions. The development process is achieved through a hardware platform consisting of an FPGA and a System on Chip in order to provide an emulation environment. The development process as well as the results obtained (in terms of throughput and fairness) through the evaluation of Maximum Rate (MR), Round Robin (RR), Proportional Fair (PF) and a proposed novel UE-based Maximum Rate (UEMR) scheduling algorithms are presented. Using MBD together with MBT the developed scheduling algorithms can be further enhanced and exported to real world applications.

Evaluation of SINR Prediction in Cellular Networks

ABSTRACT In this article, we present an evaluation of the techniques for the prediction of the signal-to-interference-plus-noise ratio (SINR) within cellular networks, with an emphasis on the capability to predict more than a single measurement of SINR towards the future. When the predictive techniques are used to forecast four or less measurements of the SINR into the future and the user moves at a speed of 30 km/h or above, the predictive technique based on recursive least squares presents an error between 1.0% and 20.5% smaller than the predictive techniques based on Taylor series and Markov model.

Analytical estimation of service requests capacity in LTE-A systems with heterogeneous traffic

The scheduler is the entity within Long Term Evolution wireless systems responsible for the assignment of time and frequency resources to users. In this work we present an analysis to determine the scheduling Service Requests Capacity for Long Term Evolution Advanced systems, defined as the quantity of service requests the scheduler is able to dispatch in a given period of time. This methodology can be used to evaluate scheduling algorithms along with some other metrics widely employed such as system throughput, delay or fairness. Numerical results are presented for the proposed metric including upper and lower bounds considering a specific system with heterogeneous traffic in a non line of sight urban macro cellular scenario. For the case studied, results suggest that the file size has a more significant impact on the service requests capacity than the requested data rate.

Performance Evaluation of a DAB system with Space-Time Block Coding.

This paper evaluates the performance of space-time coding techniques applied to a digital audio broadcasting (DAB) system. The proposed scheme uses two transmitter antennas and one receiver antenna. This work investigates the way space and time diversity can decrease the distortion due to multipath fading and interference from other users and improve bit error rate. Numeric results show that space-time codes are a good way to improve the performance of a system DAB and the quality of additional information services.