Energy Efficient Multiuser Scheduling: Statistical Guarantees on Bursty Packet Loss

In this paper, we consider energy efficient multiuser scheduling. Packet loss tolerance of the applications is exploited to minimize average system energy. There is a constraint on average packet drop rate and maximum number of packets dropped successively (bursty loss). A finite buffer size is assumed. We propose a scheme which schedules the users opportunistically according to the channel conditions, packet loss constraints and buffer size parameters. We assume imperfect channel state information at the transmitter side and analyze the scheme in large user limit using stochastic optimization techniques. First, we optimize system energy for a fixed buffer size which results in a corresponding statistical guarantee on successive packet drop. Then, we determine the minimum buffer size to achieve a target (improved) energy efficiency for the same (or better) statistical guarantee. We show that buffer size can be traded effectively to achieve system energy efficiency for target statistical guarantees on packet loss parameters.Comment: Proc. Physcomnet in conjunction with WIOPT 201

Trading Wireless Information and Power Transfer: Relay Selection to Minimize the Outage Probability

This paper studies the outage probability minimization problem for a multiple relay network with energy harvesting constraints. The relays are hybrid nodes used for simultaneous wireless information and power transfer from the source radio frequency (RF) signals. There is a trade-off associated with the amount of time a relay node is used for energy and information transfer. Large intervals of information transfer implies little time for energy harvesting from RF signals and thus, high probability of outage events. We propose relay selection schemes for a cooperative system with a fixed number of RF powered relays. We address both causal and non-causal channel state information cases at the relay--destination link and evaluate the trade-off associated with information/power transfer in the context of minimization of outage probability.Comment: IEEE GlobalSiP, 201

Effective Capacity of Cognitive Radio Links: Accessing Primary Feedback Erroneously

We study the performance of a cognitive system modeled by one secondary and one primary link and operating under statistical quality of service (QoS) delay constraints. We analyze the effective capacity (EC) to quantify the secondary user (SU) performance under delay constraints. The SU intends to maximize the benefit of the feedback messages on the primary link to reduce SU interference for primary user (PU) and makes opportunistic use of the channel to transmit his packets. We assume that SU has erroneous access to feedback information of PU. We propose a three power level scheme and study the tradeoff between degradation in EC of SU and reliability of PU defined as the success rate of the transmitted packets. Our analysis shows that increase in error in feedback access causes more interference to PU and packet success rate decreases correspondingly.Comment: Accepted for publication in International Symposium on Wireless Communication Systems (ISWCS) 201

Design and Implementation of a 2.4 GHz Millimeter Wave Radar System for Soil Water Content Detection

Because water has the highest real permittivity value, close to 80, compared to dry soils\u27 real permittivity, which ranges from 3 to 15, measuring a soil\u27s permittivity is strongly reliant on its moisture content. Furthermore, increased relative permittivity leads to a larger reflectivity coefficient. According to these perspectives, adding water to dry soil generates notable changes in wet soil permittivity and modifies the reflectance and characteristics of incident electromagnetic waves (EMWs) at the soil-air interface. Thus, the soil water content (SWC) may be reliably determined by recording variations in the properties of incident EMWs compared to a reference dry soil case. This inspired us to develop a millimeter wave radar system to measure the SWC. In this paper, the design and hardware implementation of a 2.4 GHz millimeter wave radar system is introduced for SWC measurement. The SWC measurement principle of the proposed system is based on measuring the reflection coefficient of the soil-air interface. The received analog signal is amplified before it is converted into a digital signal that is sent by the Arduino microcontroller to the computer buffer via the serial communication port to be analyzed using the designed MATLAB code