• Measurement of the Impulsive Noise Environment for Satellite-Mobile Radio Systems at 1.5 GHz.

      Button, Mark D.; Gardiner, John G.; Glover, Ian A. (2002)
      Noise amplitude distribution measurements relevant to%satellite-mobile radio systems are reported. The rationale for the%measurements is outlined and the choice of measurement parameters%justified. The measurement equipment and measurement methodology are%described in detail. Results characterizing the elevation angle%distribution of impulsive noise are presented for rural, suburban and%urban environments and also for an arterial road (U.K. motorway)%carrying high density, fast moving traffic. Measurements of the levels%of impulsive noise to be expected in each environment for high- and%low-elevation satellite scenarios using appropriate antenna%configurations are also presented
    • Method and Apparatus for Supporting Ad-Hoc Networking over UMTS (Universal Mobile Telecommunications System) Protocol.

      Barnawi, A.; Gardiner, John G. (2007)
      A method and apparatus are provided for ad hoc networking over a universal mobile telecommunications system (UMTS) . In the method, if user equipment (40A) (such as a mobile phone) is not within normal cell coverage (20) , then in an uplink procedure a message which would normally have not be able to be transmitted directly from the User Equipment (40A) to a Base Station (10) is instead forwarded towards the Base Station (10) via one or more intermediate User Equipments (40B) . In the method, the user equipment (40A) is arranged to synchronise itself with the Base Station (10) to acquire timeslot and frame synchronisations and thence perform probing activities to build up a list of neighbouring User Equipments. From this list and power and signal to interference calculations the user equipment (40A) is able to work out the relative positions of its neighbours with respect to the Base Station and itself and come to a routing decision for forwarding its message towards the Base Station.
    • A New Design of Horizontally Polarized and Dual-Polarized Uniplanar Conical Beam Antennas for HIPERLAN.

      Gardiner, John G.; Abd-Alhameed, Raed A.; Excell, Peter S.; McEwan, Neil J.; Ibrahim, Embarak M. (2003)
      It is shown that a conical beam 5.2-GHz antenna suitable for HIPERLAN application, but working in horizontal polarization, can be realized as a group of microstrip patch radiators in a ring formation. Layouts with three and four patches are described, and radiation patterns are found to agree well with predictions from a simple array model. The three-patch form is smaller and gives a closer approximation to an azimuth-independent pattern. Patterns are very similar to those achieved in vertical polarization with previously reported disk antenna realizations, giving peak radiation at about 50 elevation. Two methods of impedance matching are found to give satisfactory results. A dual-polarized conical-beam microstrip antenna, with a strictly uniplanar conductor pattern, is also presented and realized as an array of three square patches whose corners meet a central feed point. For the second polarization, the antenna functions as a series fed array. Fairly good conical beam patterns have been obtained, though only moderate polarization purity appears to be obtainable from threeelement arrays.
    • Theoretical Model to Determine the Blocking Probability for SDMA Systems.

      Galvan-Tejada, Giselle M.; Gardiner, John G. (2001)
      Antenna array technology has attracted the attention of the research community as a means to increase system capacity and improve the signal reception. Space division multiple access (SDMA) is a multi-access scheme based on the use of antenna arrays to separate users by exploiting their positions in space. Several works have been carried out to examine the improvement in the system capacity provided by SDMA. A theoretical model to determine the blocking probability for SDMA is derived. A closed-form linear system of equations is obtained whose numerical solution gives the blocking probability. The formulation is employed to assess the capacity gain improvement of a single-cell system under specific conditions. It is found from the results that SDMA is not efficient for low traffic loads, whereas it is so for high traffic.