As the power consumption is an essential issue for designers of mobile devices The 3 Generation Partnership Project (3GPP) – Long Term Evolution (LTE) employs a multicarrier communication technique on the air interface, Single Carrier Frequency Division Multiple Access (SCFDMA), in uplink scenario and Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink. SCFDMA core modulation ...

A two-way relay network provide improved spectral efficiency compared with a conventional one-way relay network by using either superposition coding or network coding. OFDMA network provides imptoved performance by adaptive resource allocation. In this paper, we propose a adaptive subcarrier allocation for a multiuser two-way OFDMA relay network. In the proposed algorithm, subcarriers are alloc...

IEEE 802.16-2004 and IEEE 802.16e-2005 standards specify OFDMA as a physical layer technique for fixed and nomadic BWA systems, respectively. OFDMA is very sensitive to time and frequency offsets. In this paper, a preamble based downlink frame synchronization method for OFDMA mode of WMAN is analyzed in frequency selective fading channels. Expressions for mean and variance of the metric are der...

In this paper, our focus is to assure a global frequency synchronization in OFDMA-based wireless mesh networks with local information. To acquire the global synchronization in distributed manner, we propose a novel distributed frequency synchronization (DFS) method. DFS is a method that carrier frequencies of distributed nodes converge to a common value by repetitive estimation and averaging st...

Orthogonal Frequency Division Multiple Access (OFDMA) has been selected as the multiple access technique to meet the growth of cellular subscribers and the need for faster and more reliable data services. The fundamental in OFDMA femtocell network is the interference management. When femtocell is deployed in the existing macrocell network, there will be a chance of interference between the femt...

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...

The Generalized Frequency Hopping (GFH) OFDMA system developed in this paper permeates FH bene ts to multicarrier CDMA transmissions through unknown frequencyselective multipath channels. No single user su ers from consistent fading e ects and multiuser interference is eliminated by design. Constellation-irrespective channel identi ability is guaranteed, and a host of blind channel estimation a...

We proposed a novel joint sub channel and resource allocation for the two-tier OFDMA network. The multi-cell OFDMA network not only has to control the interference to the users, but also has to coordinate the cross-tier interference. A resource allocation scheme for cross-channel Femto and Macro is proposed, aiming to maximize the capacity. We formulate this joint optimization for both uplink a...

This report is a tutorial on Orthogonal Frequency Division Multiplex (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA). OFDMA is the major transmission and access technology for future mobile broadband systems like Mobile WiMAX and 3GPP Long Term Evolution (LTE). One of the key features of OFDM and OFDMA is the ability to handle multipath propagation without complex receivers. Th...

To meet the requirements of high data rate, third generation partnership project (3GPP) has come across the development of long term evolution (LTE). High data rate can be achieved with the help of an advanced modulation method. Orthogonal Frequency Division Multiple Access (OFDMA) was considered as a modulation method especially in the downlink of the communication systems. It gives many advan...