Radio Systems Research Group

BSc, PhD (Leicester), MIET
T: +44 (0)116 252 2520
F: +44 (0)116 252 2619
E: sto@le.ac.uk

Location: Room 11, R Block, Engineering

Main Research Interests:

Sub-auroral HF radio propagation
Recent research interests have focussed on taking measurements of the directions of arrival, time of flight, Doppler and multipath spreads, and strength of signals propagated over two paths roughly tangential to the midlatitude trough. Of particular interest is a comparison between the measurements taken near sunspot minimum (2006–07) with those taken at sunspot maximum (2000–01) since the character of the propagation differs significantly (see Figure 1). The measurements will be compared with ray tracing simulations through various model ionospheres and the models refined in a physically realistic manner to improve the agreement between the simulations and the experimental results.

Fig 1: Example observations made at sunspot maximum (top two panels) and sunspot minimum (lower two panels) of time of flight (top and third panels) and azimuth (second and lower panels).

An experimental investigation into the feasibility of MIMO techniques within the HF band
Multiple in multiple out (MIMO) is a relatively new technique that exploits the presence of multipath to enhance the channel capacity. In this technique antenna arrays are employed at both the transmitter and receiver to form a number of parallel channels, which carry different data streams. Under ideal conditions, the channel capacity can increase linearly with the smallest number of transmit / receive antennas. In this project, a frequency agile multi-tone and orthogonal code multi-channel transmitter system and a multi-channel receiving system will be implemented to provide a direct and an indirect method for the estimation of the HF channel capacity as a function of frequency. The frequency separation in the multi-tone method is chosen appropriately within the coherent bandwidth of the channel whereas, the coded transmission would provide adequate resolution of the multipath  components to enable the estimation of the parameters of the multipath components including the angle of arrival and angle of departure. The channel capacity can then be obtained from the parameters and compared with the direct multi-tone measurements. The multiple antenna channel coefficients will be applied to simulate the achievable bit error  rates in a digital communication system such as for example a MIMO/OFDM system.

• Further investigation and simulation of ionospheric radiowave propagation effects occurring over northerly paths, EPSRC, £232,874.
• An experimental investigation into the feasibility of MIMO techniques within the HF band EPSRC, £425,000 (jointly with Durham, £255,000 Leicester, £170,000 Durham).

Publications