SINR

We study the impact on 802.11 networks of RF interference from devices such as Zigbee and cordless phones that increasingly crowd the 2.4GHz ISM band, and from devices such as wireless camera jammers and non-compliant 802.11 devices that seek to disrupt 802.11 operation. Our experiments show that commodity 802.11 equipment is surprisingly vulnerable to certain patterns of weak or narrow-band interference. This enables us to disrupt a link with an interfering signal whose power is 1000 times weaker than the victim's 802.11 signals, or to shut down a multiple AP, multiple channel managed network at a location with a single radio interferer. We identify several factors that lead to these vulnerabilities, ranging from MAC layer driver implementation strategies to PHY layer radio frequency implementation strategies. Our results further show that these factors are not overcome by simply changing 802.11 operational parameters (such as CCA threshold, rate and packet size) with the excep...

This paper proposes distributed joint power and admission control algorithms for the management of interference in two-tier femtocell networks, where the newly-deployed femtocell users (FUEs) share the same frequency band with the existing macrocell users (MUEs) using code-division multiple access (CDMA). As the owner of the licensed radio spectrum, the MUEs possess strictly higher access priority over the FUEs; thus, their quality-of-service (QoS) performance, expressed in terms of the prescribed minimum signal-to-interference-plus-noise ratio (SINR), must be maintained at all times. For the lower-tier FUEs, we explicitly consider two different design objectives, namely, throughput-power tradeoff optimization and soft QoS provisioning. With an effective dynamic pricing scheme combined with admission control to indirectly manage the cross-tier interference, the proposed schemes lend themselves to distributed algorithms that mainly require local information to offer maximized net utility of individual users. The approach employed in this work is particularly attractive, especially in view of practical implementation under the limited backhaul network capacity available for femtocells. It is shown that the proposed algorithms robustly support all the prioritized MUEs with guaranteed QoS requirements whenever feasible, while allowing the FUEs to optimally exploit the remaining network capacity. The convergence of the developed solutions is rigorously analyzed, and extensive numerical results are presented to illustrate their potential advantages.

Mobile operators commonly use macro cells with traditional wide beam antennas for wider coverage in the cell, but future capacity demands cannot be achieved by using them only. It is required to achieve maximum practical capacity from macro cells by employing higher order sectorization and by utilizing all possible antenna solutions including smart antennas. This paper presents enhanced tessellation for 6-sector sites and proposes novel layout for 12-sector sites. The main target of this paper is to compare the performance of conventional wide beam antenna, switched beam smart antenna, adaptive beam antenna and different network layouts in terms of offering better received signal quality and user throughput. Splitting macro cell into smaller micro or pico cells can improve the capacity of network, but this paper highlights the importance of higher order sectorization and advance antenna techniques to attain high Signal to Interference plus Noise Ratio (SINR), along with improved network capacity.  Monte Carlo simulations at system level were done for Dual Cell High Speed Downlink Packet Access (DC-HSDPA) technology with multiple (five) users per Transmission Time Interval (TTI) at different Intersite Distance (ISD). The obtained results validate and estimate the gain of using smart antennas and higher order sectorization with proposed network layout.

Seamless handover between different access technologies is a great challenge as it needs to obey different performance of QoS and security constraints. Subscribers are becoming more demanding regarding roaming capabilities across different networking technologies such as WiFi, WiMAX, and CDMA as they claim service continuity with QoS requirement and good security features. In this paper, a QoS based vertical handover mechanism between WiMAX and WiFi networks is proposed by applying the Signal to Interference and Noise Ratio SINR. The Media Independent Handover MIH (IEEE 802.21) protocol is adopted to assist in the handover decisions by providing a suitable platform for vertical handovers. The performance of the proposed SINR based vertical handover algorithm and RSS based vertical handover algorithm have been evaluated in terms of the maximum downlink throughputs.

In this paper a new distributed power control algorithm is proposed. It is based on the minimization of multiple objectives. The objectives are to keep the transmitted power as close to the minimum power as possible and simultaneously, to hold the carrier to interference ratio (CIR) close to the given target. The multi-objective optimization problem is transformed into a single-objective optimization problem. Its solution results in a new, efficient power algorithm, which is simple to implement. Simulations demonstrate that it converges faster than the conventional power control algorithms. Also, the average transmitted power is less than the average transmitted power using the conventional methods with comparable quality of service (QoS). Noisy, dynamical environment is assumed in the simulations. The algorithm has been modified to work with quantized carrier to interference ratio (CIR). A new soft dropping algorithm based on a multi-objective technique has been developed.

This paper aims to show the effect of macrocellular network densification on the capacity, energy and cost efficiency. The presented results are based on radio propagation simulations that consider macrocellular network with different inter-site distances, i.e. different site densities, and also take into account the presence of indoor receiver points by varying outdoor and indoor receiver distribution. It is observed that as a result of densifying the network, the cell spectral efficiency reduces due to increasing level of inter-cell interference. However, as a result of densification, the network area capacity can be improved since the area spectral efficiency increases. Nevertheless, the densification efficiency decreases because of the reduction of cell spectral efficiency, especially when indoor receiver points are taken into account. The results hence indicate that densification of macrocellular network suffers from inefficiency which results in higher energy and cost per bit per Hertz, and thus calls for alternative methods to deploy networks, or alternatively, more sophisticated methods, such as base station coordination or inter-cell interference cancellation techniques, to be implemented for future cellular networks

The great increase in user demand to roam among various wired and wireless communications networks without affecting the signal quality has attracted many researchers to investigate about the best handover decision criteria that promote seamless handover. IEEE 802.21 Media Independent Handover (MIH) standard can be considered to be the best environment for handling both horizontal and vertical handover. In this work, we propose a new decision criteria based on MIH signalling among WLAN and WiMAX networks which depend on the received S ignal to Interference and Noise Ratio (S INR) instead of the traditional Received S ignal S trength (RS S) criteria. In order to provide multimedia QoS inside the integrated network environment, the proposed VHD provides the knowledge of the achievable bandwidth from both networks by using the re ceived S INR. S imulation-based outputs along with analytical results have confirmed that our proposal would offer the end user with better performance during the handover stage.

In this paper we study the topological properties of wireless communication maps and their usability in algorithmic design. We consider the SINR model, which compares the received power of a signal at a receiver against the sum of strengths of other interfering signals plus background noise. To describe the behavior of a multi-station network, we use the convenient representation of

A novel wideband beamforming technique for cellular CDMA systems is presented. The proposed algorithm asymptotically provides the optimum combination of space-time samples to maximize the SINR for the signal with the desired code (SDC) by optimally combining its multipath and canceling strong multiuser access interference (MUAI). In contrast to previously proposed techniques, code synchronization for the SDC is not required. The algorithm presented asymptotically provides the exact time of arrivals of the multipaths within a bit period, and subsequently the optimum space-time weights for combining the fingers across both space and time. The instrumental property exploited in this technique is the fact that although the respective spectra of the SDC and MUAI components at the output of the matched filter are statistically equal, the respective spectra of their squared values differ

In modern cellular system such as LTE Advanced (LTE-A), frequency reuse scheme is targeted to be applied to fulfill the requirement of high capacity broadband access and high spectrum efficiency. But this kind of frequency planning may lead to the worse inter-cell interference (ICI) level experienced especially by a user located at the cell edge. Soft Frequency Reuse (SFR) is considered as an effective way to mitigate inter-cell interference and maintain capacity. We propose a power division SFR, known as multi level SFR technique to minimize ICI in a designed LTE-A network for suburban environment. Service area of LTE-A network was first developed to deploy particular number of eNB by using LTE network planning tools in the frequency of 1800 MHz with the use of SISO (Single Input Single Output) antennas. Coverage dimensioning and propagation consideration determine LTE-A parameters which were used in the simulation. Monte carlo simulation is executed to examine the performance of SFR for LTE-A downlink transmission to address different power ratio and traffic loads problem. Both performance of cell edge users and overall cell performance are evaluated in terms of CINR, BLER, and throughput. Performance with SFR is also compared with the classical frequency reuse one and three.

LTE is an emerging wireless communication technology to provide high-speed data service for the mobile phones and data terminals. To improve indoor coverage and capacity Femtocells are included in 3GPP since Release 8. There is no common simulation platform is available for performance justification of LTE-Femtocells. LTE-Sim is an object-oriented open source simulator which incorporates a complete protocol stack can be used for simulating two-tier macro-femto scenarios. To the best of our knowledge no paper provides the guideline to perform system level simulation of Femtocell networks. Here, in this paper Femtocells performance is evaluated in multi-Macrocells and multi-Femtocells environment with interference from Microcells and Macrocell users along with the scripting. KEYWORDS Channel quality indicator (CQI), Femto Access Point (FAP), Macro eNodeB (MeNB), Macrocell User Equepment (MUE), Moblity Management Entity(MME), Signal to Interference Plus Noise Ratio(SINR), Physical Layer(PHY)

Most distributed power control algorithms have been proposed assuming constant interference and constant path gain. These considerations may result in lower performance gains in fast time-varying channel conditions. The two algorithms presented herein address this problem efficiently and the first is also a generalization of other previously studied distributed power control algorithms.

The Femto-Macro heterogeneous network is a promising solution to improve the network capacity and coverage in mobile network. However interference may rise due to femtocell deployment nearby to macro user equipment (MUE) within macrocell network coverage. Femtocell offers main priority in resource allocation to its subscribed femto user equipment (FUE) rather than unsubscribed MUE. MUEs will suffer severe interference when they are placed near or within the femtocell area range especially at the cell edge. This phenomenon occurs due to the distance is far from its serving macro base station (MBS) to receive good signal strength. This paper presents a design of cell selection scheme for cell-edge MUE to select an optimal femto base station (FBS) as its primary serving cell in physical resource block allocation. In this study, the proposed cell selection consists of four main elements: measuring the closest FBS distance, Signal to Interference-plus-Noise-Ratio (SINR), physical resource block (PRB) availability and node density level for the selected base station. The main goal is to ensure cell-edge MUE has priority fairly with FUE in physical resource block allocation per user bandwidth demand to mitigate interference. Hence, the cell-edge MUE has good experienced on receiving an adequate user data rate to improve higher network throughput.

We present a new method to estimate the clutter-plus-noise covariance matrix used to compute an adaptive filter in space-time adaptive processing (STAP). The method computes a ML estimate of the clutter scattering coefficients using a Bayesian framework and knowledge on the structure of the covariance matrix. A priori information on the clutter statistics is used to regularize the estimation method. Other estimation methods based on the computation of the power spectrum using for instance the periodogram are compared to our method. The result in terms of SINR loss shows that the proposed method outperforms the other ones.