Global Resource Scheduler in a Mobile Communications System Featuring Heterogeneous Architecture

Abstract

Este artículo aborda el problema de la asignación dinámica de recursos en el enlace de bajada de un sistema de comunicaciones móviles (SCM) que utiliza multiplexión por división ortogonal de frecuencia (OFDMA, por “Orthogonal Frequency Divisiom Multiple Access”). Según Metha et al. [1], se trata de un problema complejo, constituido por tres tareas interrelacionadas: la selección y la asignación de los bloques de frecuencias a los usuarios, la asignación de los bits transportados en cada bloque y la asignación de potencia a cada bloque. This article addresses the dynamic resource allocation problem (power and frequency resources) for the downlink of a multicell, multiservice mobile communication system with heterogeneous architecture, deployed into a urban environment, using OFDM (Orthogonal Frequency Division Multiplexing) at the physical level. The proposed optimization model aims to fairly satisfy the user service requirements, yielding effective resource usage, and using the Signal-to-Noise plus Interference Ratio (SINR) as a quality metric. Due that the model is integer, non-linear and mixed, and it is complex to directly obtain a solution from such a model, we use an approximate algorithm that decouples the problem solution space, and an iterative improvement strategy. The scheduler allocates resources aiming to reach the required SINR for each user, using the system global vision. Since it is not always possible to accomplish this, the scheduler takes advantage of the elasticity of some of the offered services, and incorporates a slack variable, in order to always guarantee a feasible model and obtain high value performance.