We propose a hybrid multiple access (HMA) for uplink orthogonal frequency division multiple access (OFDMA) systems, which combines two resource sharing schemes: a scheduling-based resource allocation (SBRA) scheme and a contentionbased resource allocation (CBRA) scheme. The SBRA scheme is appropriate for non-real time high data rate traffic, and, CBRA is appropriate for near-real time low/mediu...

In this paper, a channel estimation algorithm in frequency domain for IFDMA is introduced. Moreover, a post processing algorithm for further improvement of the channel estimation is presented. The performance of IFDMA is analyzed and compared to DFT precoded OFDMA with blockwise subcarrier allocation with and without frequency hopping in terms of overhead that occurs due to pilot assisted chann...

Inefficient spectrum allocation and the burgeoning problem of spectrum scarcity have prompted an examination of how the radio frequency spectrum is utilized. The radio frequency spectrum is an important national resource that impacts the economy, national security and daily life. Various studies have taken up the task of rethinking spectrum licensing and allocation with the intent of encouragin...

Anti-collision algorithms are very important to solve the anti-collision problem in multi-tag and multi-reader environment. The anti-collision algorithm is divided into the anti-collision algorithm for multiple tags and the anti-collision algorithms for multiple readers. The anticollision algorithms for multiple tags are largely divided into tree-based deterministic algorithms and slot aloha-ba...

The increasing demand for wireless communication introduces efficient spectrum utilization challenge. To address this challenge, cognitive radio (CR) is emerged as the key technology; which enables opportunistic access to the spectrum. CR is a form of wireless communication in which a transceiver can intelligently detect which communication channels are in use and which are not, and instantly m...

The next generation (4G) wireless systems are expected to provide universal personal and multimedia communications with seamless connection and very high rate transmissions and without regard to the users' mobility and location. OFDM technique is recognized as one of the leading candidates to provide the wireless signalling for 4G systems. The major challenges in downlink multiuser OFDM based 4...

As wireless networks evolve to orthogonal frequency division multiple access (OFDMA) systems, inter-cell interference control becomes a critical issue in radio resource management. The allocation of the same channels in neighbor cells cause inter-cell interference, so the channel allocation needs to be taken carefully to lower the inter-cell interference. For channel allocation, we consider two...

Inorder to enhance the capacity and output of a downlink orthogonal frequency division multiple access(OFDMA) network, it is essential to perform appropriate resource allocation. Correct resource allocation suggests that finding best subchannel and power allocation for each and every user. Therefore here associate algorithm is proposed to attain this. Initial of all sub-channel allocation is pe...