Centralized vs Distributed Resource Allocation in Multi-Cell OFDMA Systems

Abstract

Radio Resource Management with Inter-cell Inter- ference Coordination (ICIC), is a key issue under investigation for next generation wireless systems such as Long Term Evolu- tion (LTE). Although centralized resource allocation (RA) and collaborative processing can optimally perform ICIC, the overall required complexity suggests the consideration of distributed techniques. In this paper we propose and compare a centralized RA strategy aimed at maximizing the sum-rate of a multi-cell clustered system in presence of power and fairness constraints, and a distributed RA strategy where inter-cell interference is partially coordinated through power planning schemes with preassigned power (an example is fractional frequency reuse). The distributed RA strategy reduces both signaling and feedback requirements, preserves intra-cell fairness and jointly works with a load bal- ancing algorithm to support inter-cell fairness. We show in the results that the distributed RA with aggressive frequency reuse is able to approach the performance of the centralized RA when the number of users is large, while preserving the same level of fairness

A Survey on Inter-Cell Interference Coordination Techniques in OFDMA-Based Cellular Networks

“…However, coordination is still needed between eNBs to exchange CSI reports in order to perform global ICIC. Such coordination must be taken into consideration when designing coordinated distributed schemes, especially in very fast fading environments due to the fact that the LTE X2 interface used for coordination has a non-negligible latency [45].…”

“…Instead, each eNB assigns channels to its UEs on its own based only on the local information collected from its UEs. Eliminating the signaling overhead provides the key advantage of autonomous schemes as the performance of the scheduling algorithm becomes independent of the non-negligible latency caused by the interface connecting the eNBs [45]. Thus, decisions can adapt faster to the instantaneous channel and changing traffic conditions.…”

“…2) S = P AD UE (r 1 , r 2 , f) Schemes: In [45], a distributed resource allocation algorithm is proposed by Cicalo et al to preserve intra-cell fairness and coordinate offline with neighboring cells for load balancing to support inter-cell fairness. The scheme provides an inter-cell interference partial coordination and uses the FFR static scheme for power planning to reduce computational complexity.…”

“…To achieve such cooperation, information need to be exchanged between the eNBs. In practical systems, the LTE X2 interface has a considerable latency [45], resulting in an additional delay on the exchanged information, that should be taken into account, especially in very fast fading environments. Thus, ICIC schemes should minimize the amount of information need to be exchanges in order to comply with the stringent time required to exchange the scheduling information.…”

Interference Management in Lte Downlink Networks

“…When RBs are being restricted by eNB, a scheme requires to make a compromise between the value of lessening the ICI in adjacent cells and the cost of utilizing the spectrum available [7]. Some example of autonomous-distributed ICIC schemes can be found in [36][37][38][39][40].…”