Cognitive radio networks (CRNs) have received considerable attention and viewed as a promising paradigm for future wireless networking. Its major difference from the traditional wireless networks is... Show More

Cognitive radio networks (CRNs) have received considerable attention and viewed as a promising paradigm for future wireless networking. Its major difference from the traditional wireless networks is that secondary users are allowed to access the channel if they pose no harmful interference to primary users. This distinct feature of CRNs has raised an essential and challenging question, i.e., how to accurately estimate interference to the primary users from the secondary users? In addition, spectrum sensing plays a critical role in CRNs. Secondary users have to sense the channel before they transmit. A two-state sensing model is commonly used, which classifies a channel into either busy or idle state. Secondary users can only utilize a channel when it is detected to be in idle state. In this paper, we tackle the estimation of interference at the primary receiver due to concurrently active secondary users. With the spectrum sensing, secondary users are refrained from transmitting once an active user falls into their sensing range. As a result, the maximum number of simultaneously interfering secondary users is bounded, typically ranging from 1 to 4. This significant conclusion considerably simplifies interference modeling in CRNs. The authors present all the cases with possible simultaneously interfering secondary users. Moreover, the authors derive the probability for each case. Extensive simulations are conducted and results validate the effectiveness and accuracy of the proposed approach.

Due to the advancement of telecommunication platform, users are now demanding new applications such as Online Gaming, mobile TV, Web 2.0, and to meet this requirement operators needed to design more... Show More

Due to the advancement of telecommunication platform, users are now demanding new applications such as Online Gaming, mobile TV, Web 2.0, and to meet this requirement operators needed to design more flexible network. To fulfill the requirements, 3rd Generation Partnership Project (3GPP) works on the Long Term Evolution (LTE) and propose a system which has larger bandwidths (up to 20 MHz), low latency and packet optimized radio access technology having peak data rates of 100 Mbps in downlink and 50 Mbps in the uplink (Magdalena, 2007; Motorola, 2007; Skold, 2009). Offering a greater coverage by providing higher data rates over wider areas and flexibility of use at existing and new frequency bands plan is a major challenge. In this paper, we are analyzing practical coverage scenario in an urban area (i.e. Kolkata) in terms of received signal levels, total noise, interference, throughput, and quality factor for downlink signal level.

Context-aware applications have been gaining huge interest in the last few years. With cell phones becoming ubiquitous computing devices, cell phone localization has become an important research... Show More

Context-aware applications have been gaining huge interest in the last few years. With cell phones becoming ubiquitous computing devices, cell phone localization has become an important research problem. Database Correlation Method (DCM) is a positioning technology that based on a database of a premeasured location dependent variable such as Received Signal Strength (RSS). DCM has shown superior in terms of accuracy. Absolute RSS values received from a base station change with time, but the relative RSS (RRSS) values which refer to the relations of the RSS values between different base stations are more stable. This study proposes and implements a robust RRSS GSM-based technique for both positioning and traffic estimation. The study was tested and analyzed in Egypt roads using realistic data and Android smart phones. The performance evaluation showed good results. Mean positioning accuracy was about 29m in urban areas and velocity estimation was about 1 km/h in rural areas.

As mobile contact lists get bigger and bigger the cognitive load on the user increases while trying to retrieve the next contact to start a communication session. In this paper we focus on the task... Show More

As mobile contact lists get bigger and bigger the cognitive load on the user increases while trying to retrieve the next contact to start a communication session. In this paper we focus on the task of retrieving a contact when the purpose is to start a phone call, examining mobile users’ call logs and showing that it is possible to accurately predict the next contact to be called using relatively simple heuristics and algorithms that describe usage context. The authors present and discuss the results of the proposed method applied on a dataset collected from an experiment the authors organised involving 25 mobile users.

Radio Frequency Identification (RFID) is an important wireless communication and pervasive computing technique used for automatic item identification and data capture. In this paper, we present a... Show More

Radio Frequency Identification (RFID) is an important wireless communication and pervasive computing technique used for automatic item identification and data capture. In this paper, we present a scheme for securely tracing material flow in supply chains using the inherent RFID authentication and data logging capability. The scheme provides not only an overall path tracing and verification through the entire supply chain, but also the product identification within the scope of a supply chain partner. RFID tags and readers are deployed to ensure that only authorized supply chain partners can identify the tagged items in a secure and private way. The authors develop tag-reader authentication protocols to ensure the authenticity of RFID tags and readers. Their approach avoids the single point failure of the supply chain server – there is no need for each supply chain partner to communicate with the server for every material flow. Therefore, it minimizes the risks caused by system interruptions due to network failures or server unavailability.