In this paper, a distributed and autonomous technique for resource and power allocation in orthogonal frequency division multiple access (OFDMA) femto-cellular networks is presented. Here, resource blocks (RBs) and their corresponding transmit powers are assigned to the user(s) in each cell individually without explicit coordination between femto-base stations (FBSs). The "allocatability" of each resource is determined utilising only locally available information of the following quantities:• the required rate of the user;• the quality (i.e., strength) of the desired signal;• the level of interference incident on each RB; and• the frequency-selective fading on each RB.Using a fuzzy logic system, the time-averaged values of each of these inputs are combined to determine which RBs are most suitable to be allocated in a particular cell, i.e., which resources can be assigned such that the user requested rate(s) in that cell are satisfied. Furthermore, link adaptation (LA) is included, enabling users to adjust to varying channel conditions. A comprehensive study in a femto-cell environment is performed, yielding system performance improvements in terms of throughput, energy efficiency and coverage over state-of-the-art inter-cell interference coordination (ICIC) techniques.
Index Termsautonomous resource allocation, distributed ICIC, fuzzy logic, OFDMA, femto-cellular networks.
I. INTRODUCTIONFuture wireless networks are moving towards heterogeneous architectures, where in each cell a user may have over four different types of access points (APs) (e.g., macro-, pico-, femtocells, relays and/or remote radio heads) [1]. Intuitively, this has many positive effects for a September 14, 2018 DRAFT 2 mobile station (MS), which can now choose from several base stations (BSs) to find the most suitable. However, pico-and femto-cellular overlays also imbue many difficulties, e.g., cellorganisation/optimisation, resource assignment to users, and especially interference coordination between APs within the same and neighbouring cells. Standard inter-cell interference coordination (ICIC) techniques based on network architectures [2, 3] only go so far in dealing with these challenges, and hence a new approach is necessary.
A. Challenges in Heterogeneous Networks (HetNets)Through the various types, locations and dense deployment of APs, and the different transmissions powers/ranges associated with them, numerous technical challenges are posed by femto/picocell overlays [1,4,5]. These mainly fall into the following areas:• Network self-organisation -Self-configuration and -optimisation are required of all cells.In cellular networks, such organisation can be performed via optimisation techniques [6], however these tasks become increasingly difficult given the additional APs and network parameters to be considered, motivating a distributed configuration approach [7].• Backhauling -Connecting the different BSs to the core-network necessitates extra infrastructure [1]. In the femto-cell case, the long delay of connection via wired backhaul...