Some OFDMA-based wireless commuication systems, e.g., Wireless Broadband Internet (WiBro) or Worldwide interoperability for Microwave Access (WiMAX), support frequency reuse of 1 to maximize spectral efficiency. One of the efficient methods to reduce co-channel interference (CCI) caused by frequency reuse is fractional frequency reuse (FFR). In this paper, we propose and validate a novel frequency partitioning method and subcarrier assignment mechanism to improve system and individual capacity of mobile systems using FFR.

In Master-driven TDD based Bluetooth, active Slaves should always listen in the Master-Slave slots because a Slave can transmit packets only after the master polls the Slave. This paper proposes an efficient power management policy to minimize the receiving power which is unnecessarily wasted in Bluetooth. The proposed policy is not controlled by LM (Link manager) protocol, does not need the information about Master-Slave buffers, and guarantees that Slave is in a receive state at Master's polling time. Therefore, there is no degradation of throughput by the proposed policy. The mathematical analysis is carried out in order to investigate our proposed policy. The numerical results show that the proposed policy significantly reduces power consumption over the nave Bluetooth specification.

The Bluetooth system provides point-to-point or point-to-multipoint communications with no peer-to-peer communication. For peer-to-peer communication, a slave should be able to communicate with other slaves as well as a master. To do this, the master should indirectly forward the packets. However, the end-to-end delay of forwarding packets may be increased because the packets should be forwarded at network layer. Forwarding packets for peer-to-peer communications may also bring about some needless waste of wireless resource. In this paper, we propose the addressing policy for efficient peer-to-peer communications in Bluetooth. We also address the dynamic master selection policy in which a master is dynamically selected in order to minimize the average channel occupancy. To dynamically change master in a piconet, the master-slave switching should be executed as soon as possible. Therefore, we propose the fast master-slave switching mechanism in order to minimize the switching delay. It is observed from the simulations that our proposed policies perform better than the naive Bluetooth specification.

Some wireless OFDMA communication systems support the frequency reuse factor of 1. In order to reduce co-channel interference (CCI) caused by neighbor cells, the fractional frequency reuse (FFR) can be employed. A promising frequency partitioning policy and subcarrier allocation for FFR are essential. In this letter, we employ an efficient frequency partitioning mechanism with less interference and propose an efficient subcarrier allocation algorithm to maximize the sum of users capacity under FFR. We show that the proposed algorithm has higher spectral efficiency than the conventional method as well as significantly high system fairness.