Modern cellular systems have adopted dense frequency reuse to address the growing amount of mobile data traffic. The system capacity is improved accordingly; however, this at cost augmented Inter-Cell Interference (ICI). Recently, Fractional Frequency Reuse (FFR) has emerged as an efficient ICI management scheme in Orthogonal Frequency-Division Multiple Access (OFDMA)-based systems. However, FF...

It is foreseen that a single (wideband) air interface mode is not sufficient for achieving the high spectral efficiency targets set for next generation wireless system. A dual-bandwidth approach is adapted to simultaneously provide wide coverage and high capacity in a large range of different operating environments. In this paper, hybrid diversity-multiplexing scheme, where Space-time Turbo Cod...

As the inter-cell interference becomes a great challenge in frequency reuse one systems, soft frequency reuse (SFR) has been widely used to deal with the severe inter-cell interference especially for cell edge users. This paper proposes an analytical method to investigate the statistics of inter-cell interference in uplink orthogonal frequency division multiple access systems when SFR scheme is...

In the prevailing cellular environment, it is important to provide the resources for the fluctuating traffic demand exactly in the place and at the time where and when they are needed. In this paper, we explored the ability of hierarchical cellular structures with inter layer reuse to increase the capacity of mobile communication network by applying total frequency hopping (T-FH) and adaptive f...

For broadband cellular access based on orthogonal frequency division multiple access (OFDMA), fractional frequency reuse (FFR) is one of the key concepts for mitigating inter-cell interference and optimizing cell-edge performance. In standard FFR, the number of OFDMA sub-bands and the reuse factor are fixed. Whereas this works well for an idealized cell pattern, it is neither directly applicabl...

The co-channel cell interference (CCI) becomes the major performance degradation factor for multi-cell OFDMA systems. In this paper, we propose two fractional frequency reuse (FFR) schemes that can efficiently avoid the CCI in the cell edge: scheme I where each cell is divided into two regions: the central region and the edge region. In the central region, the frequency reuse is set to 1. In th...

Buffer cache algorithms play a major role in filling the large performance gap between main memory and I/O devices in a mass storage system. Many buffer cache algorithms have been developed such as the low inter-reference recency set (LIRS) and adaptive replacement cache (ARC). Careful analysis of real-world workloads leads us to observe that approximately 50 to 90% blocks are accessed three or...

We design truthful double spectrum auctions where multiple parties can trade spectrum based on their individual needs. Open, market-based spectrum trading motivates existing spectrum owners (as sellers) to lease their selected idle spectrum to new spectrum users, and provides new users (as buyers) the spectrum they desperately need. The most significant challenge is how to make the auction econ...

This paper proposes a vertical beamforming concept to a cellular network employing Fractional Frequency Reuse technique including with cell sectorization. Two different beams are utilized in cell-center and cell-edge, separately. The proposed concept is validated through computer simulation in term of SINR and channel capacity. Also, comparison when utilizing horizontal and vertical beam format...

Femtocells underlay in macro-cellular network is becoming more popular in order to use spatial frequency reuse gain, extend the coverage and capacity. But interference mitigation is the main challenge for the system designer. Instead of using centralized coordination among base stations to mitigate or reduce interference caused by femtocells to macrocells, this paper investigates the dynamic di...