An optimal subcarrier allocation algorithm is proposed for orthogonal frequency division multiple access systems over Rayleigh fading channels with channel state information feedback. The transmitted orthogonal frequency division multiple access frame is divided into groups called subchannels according to the detected number of users at the base station. The pilots are reduced for the stable su...

In this paper a distributed approach to radio scene analysis is considered. A Wireless Sensor Network, composed by Software Defined and Cognitive terminals, is used to classify air interfaces present in the radio scene. Two modes, namely Frequency Hopping Code Division Multiple Access and Direct Sequence Code Division Multiple Access, are identified employing a signal processing technique, Time...

Orthogonal Frequency Division Multiple Access (OFDMA) appears today as a strong candidate in on-going standardization. Despite its attractive features, it has several drawbacks when employed in the uplink: The high peak-to-average power ratio (PAPR) inherited from Orthogonal Frequency Division Multiplexing (OFDM) and the inherent frequency diversity loss. The loss of frequency diversity can be ...

To, My father, Narendra and my mother, Jyotsna for their patience and support for all these years. iii PREFACE This thesis is an attempt to provide a holistic solution to the receiver implementation for the broadband fixed wireless access (BFWA) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. OFDM has been adopted into several wire-line and wirel...

In this paper, a comparative estimate of the channel capacity assigned to each user for frequencydivision multiple-access (FDMA) and direct-sequence code-division multiple-access (DS-CDMA) schemes operating in a Rayleigh fading channel is presented. Then, the achievable channel capacity per user (in the Shannon sense) is estimated in an average sense considering the inherent diversity potential...

Orthogonal frequency division multiplexing (OFDM) is considered as one of the most promising techniques for next-generation wireless access systems. However, it may suffer from the so-called other-cell interference (OCI) in cellular environments. In this paper, we consider a novel resource allocation scheme to reduce the OCI in OFDM-based asynchronous cellular systems. The proposed scheme can r...

The 4G wireless networks are being developed to make use of the latest developments in wireless technology domain. These networks are envisioned to offer higher bandwidths, up to 100 Mbps, global roaming, and network scalability. Coded OFDM, a combination of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA) has been considered as an efficient technique d...

Frequency-hopping (FH) methods in the Orthogonal frequency division multiplexing access(OFDMA) system,which are to assign user-specific subcarrier to the active users, have been paid much attention to in the broadband wireless communication system. In this paper, we present a novel multiple access scheme, referred to as CDM-FH-OFDMA, which is the extension of FH-OFDMA with code division multipl...