DYNAMIC FRACTIONAL FREQUENCY REUSE IN OFDMA SYSTEMS

Abstract

We are recommending a frequency reuse scheme for reducing the co-channel interference (CCI) in multi-cell OFDMA systems. We are dividing all the available subcarriers into two groups from them we are using one of them for the boundary and one for the central region. We have a frequency reuse factor (FRF) of one in the center of the cell and a reuse factor of three at the boundary. Edge of the given cell is divided into three sectors. Intra-cell orthogonality is ensured in this scheme, so we can ensure that all the subcarriers to be able to utilize the same transmit power. We are allocating all the subcarriers to super and regular group in a different manner which is depending on the distribution of the users and its requirements of the service. The group of frequencies that are used by user are defined by distance present between the user and also by the different parameters given as the serving base station and the other parameter is SINR(i.e. the signal to interference plus noise ratio) of the user. A two user, two cell system is used to differentiate between reuse-1 and reuse- 1/2 schemes which have users distance varied from their respective base station. Also we will be calculating the capacity of both the reuse schemes by deploying the sub-band formation in OFDMA. Simulations obtained by us are showing that any reuse is dependent on the user location. An algorithm is utilized for allocation of the sub-carrier and power which helps us to achieve low value of out-of-cell interference with the help of a scheme known as dynamic fractional frequency reuse (FFR), this is defined on orthogonal frequency division multiple access (OFDMA). Our main focus is on the data with constant-bit-rate (e.g., VoIP i.e Voice over IP). We are allocating the resources to all the sectors repeatedly in each sectors. This algorithm does not requires prior planning of the frequency and inter-cell coordination.