IEEE Second International Symposium on Spread Spectrum Techniques and Applications
A communication scheme is proposed enabling data to be transmitted over an occupied channel by su... more A communication scheme is proposed enabling data to be transmitted over an occupied channel by superposition of a direct sequence spread spectrum signal of low power spectral density on the existing traffic. Particular attention has been paid to satellite television broadcasting but the principles in this work could be applied to any channel. Applications of this technique include engineering order
ABSTRACT This paper explores some of the techniques and issues associated with the design of an e... more ABSTRACT This paper explores some of the techniques and issues associated with the design of an effective medium access control (MAC) protocol for a geostationary satellite channel. Two satellite MAC schemes are described, combined free/demand assignment multiple access (CFDAMA) and burst targeted demand assignment multiple access (BTDAMA) and their performance is evaluated for both Poisson and self-similar data traffic. Simulation results show that the effectiveness of different MAC techniques is heavily dependent on the nature of the traffic to be supported. It is shown that the CFDAMA scheme can provide good delay/utilisation performance of a satellite channel for Poisson traffic but poorer performance for the highly bursty self-similar traffic. The BTDAMA scheme on the other hand provides good delay/utilisation performance for self-similar traffic but is less suited to handling Poisson traffic.
This Report provides an overview of the principal players and projects involving High Altitude Ai... more This Report provides an overview of the principal players and projects involving High Altitude Aircrafts or Airships (HAAS). It concentrates upon those projects which may be classed as involving 'High Altitude' platforms, although attention is also given to other platforms, such as UAVs, where relevant. Brief summaries are given of various projects together with observations and discussion. All known major
2004 Ieee 15th International Symposium on Personal Indoor and Mobile Radio Communications, Oct 5, 2004
... 2]. A periodogram-based frequency estimator for systems with multi-antenna transmission with ... more ... 2]. A periodogram-based frequency estimator for systems with multi-antenna transmission with Hadamard sequences was proposed by Hong & et a1 in [3]. An autocorrelation-based frequency estimator was proposed by Jeong, Jo and & ... (4) aH+HAH(wo)A(wo)+a __ aHra __ E ...
2004 IEEE 15th International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE Cat. No.04TH8754), 2000
ABSTRACT The burst targeted demand assignment multiple access (BTDAMA) protocols incorporate an o... more ABSTRACT The burst targeted demand assignment multiple access (BTDAMA) protocols incorporate an original approach to DAMA, which eliminates the fundamental end-to-end delay bound associated with the traditional DAMA techniques. Whilst they offer significant improvements in the achievable delay/utilisation performance for bursty packet transmission over satellite, they are constrained by the initial build up of packets at the start of traffic bursts. In this paper, we introduce the adaptivity to the uplink frame that enables the proportion of alternative types of capacity allocation to be varied on a dynamic basis. Sufficient demand assigned capacity is assigned to meet the instantaneous user requirements, with spare capacity allocated by an alternative strategy to assist with initial throughput at the start of bursts. Results show that this approach enhances the end-to-end delay distribution and delay jitter performance compared with the conventional static frame BTDAMA schemes.
A technique is described to reduce the probability of false-lock in Costas loops. This is where a... more A technique is described to reduce the probability of false-lock in Costas loops. This is where a frequency offset arises at a multiple of half the incoming data rate due to finite bandwidth of the arm filters. A modification is described to process components of this offset so as to augment the feedback control voltage. The performance is analyzed and
IEEE Second International Symposium on Spread Spectrum Techniques and Applications
A communication scheme is proposed enabling data to be transmitted over an occupied channel by su... more A communication scheme is proposed enabling data to be transmitted over an occupied channel by superposition of a direct sequence spread spectrum signal of low power spectral density on the existing traffic. Particular attention has been paid to satellite television broadcasting but the principles in this work could be applied to any channel. Applications of this technique include engineering order
ABSTRACT This paper explores some of the techniques and issues associated with the design of an e... more ABSTRACT This paper explores some of the techniques and issues associated with the design of an effective medium access control (MAC) protocol for a geostationary satellite channel. Two satellite MAC schemes are described, combined free/demand assignment multiple access (CFDAMA) and burst targeted demand assignment multiple access (BTDAMA) and their performance is evaluated for both Poisson and self-similar data traffic. Simulation results show that the effectiveness of different MAC techniques is heavily dependent on the nature of the traffic to be supported. It is shown that the CFDAMA scheme can provide good delay/utilisation performance of a satellite channel for Poisson traffic but poorer performance for the highly bursty self-similar traffic. The BTDAMA scheme on the other hand provides good delay/utilisation performance for self-similar traffic but is less suited to handling Poisson traffic.
This Report provides an overview of the principal players and projects involving High Altitude Ai... more This Report provides an overview of the principal players and projects involving High Altitude Aircrafts or Airships (HAAS). It concentrates upon those projects which may be classed as involving 'High Altitude' platforms, although attention is also given to other platforms, such as UAVs, where relevant. Brief summaries are given of various projects together with observations and discussion. All known major
2004 Ieee 15th International Symposium on Personal Indoor and Mobile Radio Communications, Oct 5, 2004
... 2]. A periodogram-based frequency estimator for systems with multi-antenna transmission with ... more ... 2]. A periodogram-based frequency estimator for systems with multi-antenna transmission with Hadamard sequences was proposed by Hong & et a1 in [3]. An autocorrelation-based frequency estimator was proposed by Jeong, Jo and & ... (4) aH+HAH(wo)A(wo)+a __ aHra __ E ...
2004 IEEE 15th International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE Cat. No.04TH8754), 2000
ABSTRACT The burst targeted demand assignment multiple access (BTDAMA) protocols incorporate an o... more ABSTRACT The burst targeted demand assignment multiple access (BTDAMA) protocols incorporate an original approach to DAMA, which eliminates the fundamental end-to-end delay bound associated with the traditional DAMA techniques. Whilst they offer significant improvements in the achievable delay/utilisation performance for bursty packet transmission over satellite, they are constrained by the initial build up of packets at the start of traffic bursts. In this paper, we introduce the adaptivity to the uplink frame that enables the proportion of alternative types of capacity allocation to be varied on a dynamic basis. Sufficient demand assigned capacity is assigned to meet the instantaneous user requirements, with spare capacity allocated by an alternative strategy to assist with initial throughput at the start of bursts. Results show that this approach enhances the end-to-end delay distribution and delay jitter performance compared with the conventional static frame BTDAMA schemes.
A technique is described to reduce the probability of false-lock in Costas loops. This is where a... more A technique is described to reduce the probability of false-lock in Costas loops. This is where a frequency offset arises at a multiple of half the incoming data rate due to finite bandwidth of the arm filters. A modification is described to process components of this offset so as to augment the feedback control voltage. The performance is analyzed and
Uploads
Papers by Tim C Tozer