Femto-cells deployment in today’s cellular networks came into practice to fulfill the increasing demand for data services. It also extends the coverage in the indoor areas. However, interference to other femto and macro-cells users remains an unresolved challenge. In this paper, we propose an interference mitigation scheme to control the cross-tier interference caused by femto-cells to the macr...

A Gaussian cognitive interference channel with state (G-CICS) is studied. In this paper, we focus on the two-sender, two-receiver case and consider the communication situation in which two senders transmit a common message to two receivers. Transmitter 1 knows only messageW1, and transmitter 2, referred to as the cognitive user, knows both messagesW1 andW2 and also the channel’s states sequence...

In this contribution1, we investigate the idea of using cognitive radio to reuse locally unused spectrum to increase the total system capacity. We consider a multiband/wideband system in which the primary and cognitive users wish to communicate to different receivers, subject to mutual interference and assume that each user knows only his channel and the unused spectrum through adequate sensing...

This paper addresses the problem of computing the achievable rates for two (and three) users sharing a same frequency band without coordination and thus interfering with each other. It is thus primarily related to the field of cognitive radio studies as we look for the achievable increase in the spectrum use efficiency. It is also strongly related to the long standing problem of the capacity re...

In this chapter, we introduce different traffic prediction techniques and discuss the process of evaluating channel availability through predicting traffic pattern of primary users for cognitive radios. When cognitive and non-cognitive users share the licensed spectrum, compared with secondary users (cognitive users), primary users have higher priority in using licensed channels. Therefore, whe...

Cognitive Radio Network has been widely researched to improve utilization of radio electromagnetic spectrum efficiency usage. Spectrum occupancy in Cognitive framework includes licensed and unlicensed users sharing set of channel over a coverage area. In this paper, we develop a 2D Markov Model to define transition rate and analyze call dropping probability for unlicensed users and channel util...

In this contribution, we investigate the idea of using cognitive radio to reuse locally unused spectrum to increase the total system capacity. We consider a multiband/wideband system in which the primary and cognitive users wish to communicate to different receivers, subject to mutual interference and assume that each user knows only his channel and the unused spectrum through adequate sensing....

Cognitive radio (CR) systems allow unlicensed secondary users to transmit on the licensed frequency bands without degrading the transmissions of licensed primary users. Combining CR with other emerging techniques such as multi-antenna relaying may bring many benefits for the secondary transmissions. In this study, the authors propose and investigate a new relay-based cooperation scheme for a CR...

Interference is assumed to be one of the main barriers to improving the throughput of communication systems. Consequently, interference management plays an integral role in wireless communications. Although the importance of interference has promoted numerous studies on the interference channel, the capacity region of this channel is still unknown. The focus of this thesis is on Gaussian interf...

In this paper, a centralized Power Control (PC) scheme aided by interference channel gain learning is proposed to allow a Cognitive Radio (CR) network to access the frequency band of a Primary User (PU) operating based on an Adaptive Coding and Modulation (ACM) protocol. The main idea is the CR network to constantly probe the band of the PU with intelligently designed aggregated interference an...