Harold Woodruff Tomlinson

Delay-hopped transmitted-reference RF communications

Previously, the authors have invented and experimented with a new radio communications scheme called delay-hopped transmitted-reference (DHTR) radio. This technique can function either as an impulse radio, or can employ a more traditional spread-spectrum carrier such as broadband noise. The DHTR method is well-suited to short-range transmissions in a high multipath environment, and, in contrast to time-modulated impulse radio, is easy to synchronize at the receiver. Finally, DHTR receivers and transmitters are not highly complex, and can be implemented in a cost-effective way.

Delay hopped transmitted reference experimental results

This paper describes the experimental hardware design and implementation for a delay hopped transmitted reference communication system. The hardware is designed to generate the delay hopped transmitted reference signal for a number of experimental conditions. It can be used either in an ultra wideband pulse mode, ultra wideband noise mode, or in a narrowband mode. We use the experimental hardware setup to conduct link experiments with a delay hopped transmitted reference communication system. Experiments were conducted in an indoor multipath environment to test the viability of delay hopped transmitted reference for short-range indoor communications. The experimental results presented demonstrate that this modulation format is capable of transmitting data short range indoors without line of sight transmission path with minimal transmitted RF power.

Energy minimization in wireless sensor networks through an adaptive connectionless scheduling protocol (adaptive CSP)

We present an approach to minimizing energy costs in wireless sensor networks through a protocol that implements near perfect scheduling based on a near perfect clock, accurate synchronization, and some discriminating node feature such as a unique identifier. Our approach is highly flexible in that options for communicating in a one-to-one or many-to-one manner are made possible without messaging overhead to set up or tear down channels. Our pseudorandom scheduling paradigm provides flexibility to serve data rate requirements over a wide range of traffic scenarios and automatically adapts to load and latency requirements, providing a high performance scheduling protocol for sensor networks and homeland security applications.

Quality of Service In Wireless Sensor Networks through the Connectionless Scheduling Protocol

The connectionless scheduling protocol is a cross layer media access protocol that uses a pseudorandom message scheduling approach to achieve near optimal channel utilization with near optimal energy utilization, providing benefit for resource constrained multi-hop applications such as wing stress monitoring. In this paper we describe how quality of service differentiation can be easily applied to this protocol by providing simple message length or schedule availability constraints. Theoretical analysis is conducted through a derived probabilistic model.