Spread spectrum mobile communication experiment using ETS-V satellite

The spread spectrum technique is attractive for application to mobile satellite communications, because of its random access capability, immunity to inter-system interference, and robustness to overloading. A novel direct sequence spread spectrum communication equipment is developed for land mobile satellite applications. The equipment is developed based on a matched filter technique to improve the initial acquisition performance. The data rate is 2.4 kilobits per sec. and the PN clock rate is 2.4552 mega-Hz. This equipment also has a function of measuring the multipath delay profile of land mobile satellite channel, making use of a correlation property of a PN code. This paper gives an outline of the equipment and the field test results with ETS-V satellite

Novel low cost synchronisation network for spread spectrum systems

Spread Spectrum systems are found in many flavours, used in many applications and have existed since the early days of radio communications. The properties of spread spectrum do however place restrictions on the design, and often make the implementation expensive and complex. When using spread spectrum to provide a basic communications infrastructure, many factors need to be considered. These include supplying the appropriate technology at the right cost. To achieve this a trade-off against performance is often required. One of the more difficult aspects of Spread Spectrum design is the synchronisation of the spreading waveform. The primary characteristic of pseudonoise sequence synchronisation is the need for two levels of synchronisation namely acquisition (course synchronisation) and tracking (fine synchronisation). In these networks (the term network is used to describe a circuit or system throughout the thesis.) a decision is required to switch between the two synchronisation modes. The two layer structure of the typical pseudonoise sequence synchronisation network can increase the overall cost of spread spectrum systems. The objective of the research was therefore to find solutions to reduce the overall cost and complexity of the synchronisation network. The synchronisation structure should perform acquisition and tracking in a single structure, and thereby be low cost. To achieve the primary objective of this dissertation a. mixture of theory, simulations and practical implementation was used. The basis of the investigation was a time-variant spectral evaluation of pseudonoise sequences. It is shown that by multiplying a differentiated pseudonoise sequence with another pseudonoise sequence, useful information is obtained that can form the basis of a synchronisation network

Timing and Carrier Synchronization in Wireless Communication Systems: A Survey and Classification of Research in the Last 5 Years

Timing and carrier synchronization is a fundamental requirement for any wireless communication system to work properly. Timing synchronization is the process by which a receiver node determines the correct instants of time at which to sample the incoming signal. Carrier synchronization is the process by which a receiver adapts the frequency and phase of its local carrier oscillator with those of the received signal. In this paper, we survey the literature over the last 5 years (2010–2014) and present a comprehensive literature review and classification of the recent research progress in achieving timing and carrier synchronization in single-input single-output (SISO), multiple-input multiple-output (MIMO), cooperative relaying, and multiuser/multicell interference networks. Considering both single-carrier and multi-carrier communication systems, we survey and categorize the timing and carrier synchronization techniques proposed for the different communication systems focusing on the system model assumptions for synchronization, the synchronization challenges, and the state-of-the-art synchronization solutions and their limitations. Finally, we envision some future research directions

Precise pseudoranges obtained from combining code and dual carrier measurements in Global Positioning System receivers

The Global Positioning System (GPS), which was declared operational in December 1993, has provided continuous worldwide navigational capabilities in all types of weather. GPS has a minimum of 24 satellites in its constellation with additional fully functional spare satellites, which vary about 30 in total number. This navigational service has provided three-dimensional position within 30 meters and time within 100 ns to the civil community, which typically uses the coarse acquisition (C/A) code. The military GPS user has improved position accuracy within 6 meters using the dual GPS frequencies that carry the precise (P) code. The coarse resolution of a code measurement is about 1/10 of the smallest bit length of either code, which is about 29 m on C/A or 2.9 m with P code. Also, the GPS phase measurements can be determined well within 1/100 of a cycle by both civil and military receivers, so that the equivalent wavelength portion will be less than 0.19 cm and 0.24 cm. Recent GPS technology has improved civil navigation close to the military precision limits;To improve the precision by at least a hundred-fold, this dissertation considers a new exact linear navigation algorithm compared to the standard iterative GPS solution and also considers a new method of measurement by combining both carrier and phase measurements to improve pseudoranges within a centimeter tolerance. The GPS signal design is described in detail, and the novel techniques are derived explicitly. A simulation illustrating the novel exact solution demonstrates the greater versatility over the standard GPS iterative method, which, in some special cases, converges prematurely. Also, the GPS navigation solution is computed using both methods with actual GPS data against surveyed benchmarks. In conclusion, this dissertation: (1) derives a new exact linear GPS navigation algorithm as an alternative to the standard iterative GPS method, (2) demonstrates the standard iterative GPS navigation solution may stall prematurely in many small regions, which are dependent on the satellite configuration, before getting to the receiver\u27s actual location, and (3) illustrates a new method that combines carrier phases with pseudorange data to obtain subcentimeter precision in the GPS pseudoranges plus improved navigation with the exact GPS algorithm