File Name: satellite communications systems systems techniques and technology .zip
This application is a continuation of U. Provisional Patent Application No. Currently excellent digital data transfer services are available in well connected areas where fibre-optic networks and new terrestrial wireless technologies permit the movement of very large volumes of data at very high speeds.
However this level of sufficient telecommunications infrastructure is primarily limited to densely populated areas of the world. Existing geostationary earth orbit GEO satellites do provide relatively high data volume transfer services but are inherently limited to specific regions, with coverage typically over or near land only.
Most of these also provide much lower data rates as their goal is to service large numbers of users each demanding a relatively smaller capacity. There are very few wideband transponders as most are limited to about 72 MHz, and even these would require a large antenna to operate at the necessarily high data rates to transfer massive volumes of data.
Although timeliness of delivery for small i. In addition this method places costly equipment requirements on the user, and transponder capacity required for very large data files is typically not available on a consistent, long-term basis.
Furthermore the time required to transfer such large files at these bandwidths requires a long and uninterrupted connection making such methods especially impractical for shipboard or mobile use. Moreover, many of such existing systems induce errors in the act of transmitting the data, which at times can amount to substantial losses of data in such a large data transfer. Even the data volumes supported by new internet satellites is generally low, as they are designed for asymmetric internet-type usage with slow transmit rates and high receive rates.
As such, internet satellites cannot support the data rates required to transfer large data files in a timely manner. In many cases the transfer of large data files is accomplished through the courier of physical media. Ignoring loss of transmitted packages, such couriers achieve a much greater rate of delivering relatively error-free data over the wireless transmission methods noted above.
Further, such couriers can be considered more secure than wireless broadcast methods. However, access to conventional courier service generally does not extend to remote areas, particularly in a timely manner, and shipments are susceptible to large delays, such as processing through customs.
The courier method for bulk data transfer tends to be labour intensive and shuttling of physical media by helicopter from ocean going vessels, while near shore, is extremely costly and not practical farther off shore. Many data sources and sinks located in remote areas do not, as of yet, have access to sufficient, or cost effective, services for the bulk transfer of data. Users in remote locations, with no viable options for transferal of large volumes of data, where complex computations or analyses are required are often forced to maintain significant de-centralized infrastructure and personnel to process the data on-site, which is operationally expensive when such options are even available.
Aspects of the invention described herein are directed to a method and system to implement a digital transport service for very large data files, currently up to hundreds of gigabytes, with global point-to-point coverage for non-real-time applications, with virtually error-free delivery in less than a day.
This method and system is scalable as technology makes advances in parallel with growing needs of the markets that are served. This system makes it possible to service a user need, for the timely movement of very large volumes of data from remote areas, that are not well served by existing or projected offerings such as existing geostationary satellites, broadband terrestrial wireless or fibre networks.
One embodiment of the invention, that addresses the above service market niche, is a store-and-forward fleet of small low earth orbit LEO communication satellites as elements of a system capable of providing bulk transfer services for large digital data files from small sized remote ground terminals, on land or over water. This embodiment, based on a small-satellite platform, focuses on such a file transfer i. The same embodiment can be adapted to also provide ultra-high bandwidth near real time transfers.
This would occur when both the source and destination terminals or a relay terminal were simultaneously in sight of the satellite. The data would be transferred from one to the other without the requirement for storage and subsequent transmission. Alternatively, intersatellite links may be employed to establish a near real-time path.
The following description of the invention provides a thorough understanding of, and enabling description for, the embodiment of the invention. Some ancillary elements are included in the description of the invention, for reference and context. However, one skilled in the art will understand that the invention may be practiced without many of these details.
In other cases, well-known system components and functions have not been shown or described in order to avoid unnecessarily obscuring the description of the embodiment of the invention. The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section.
At a high level, as shown in FIG. This embodiment provides global coverage, with extremely high data fidelity, and data delivery times of less than a day. It is noted that other embodiment permutations of this example are also feasible to implement the same or similar system and methods. The invention has a number of innovative aspects, distinct from other typical satellite communications systems, that are applicable in other fields.
For convenience some features of the system and method are summarized below. Unless described otherwise herein, the blocks depicted in FIGS. Indeed, much of the detailed description provided herein is explicitly disclosed in the provisional patent application; much of the additional material of aspects of the invention will be recognized by those skilled in the relevant art as being inherent in the detailed description provided in such provisional patent application, or well known to those skilled in the relevant art.
Error-free data transfer. This level of end-to-end data quality is equivalent to the occurrence of only one bad bit during the delivery of more than 10, files where each of about gigabytes. These techniques employ the cessation of data flow when the channel degrades and feature multiple means to only replace relatively small erroneous data blocks via a low bandwidth auxiliary channel. The receiving station notifies the sender to request these data blocks that must be resent.
Immune to poor channel events. Channel quality is ensured through a control loop based on the monitoring of channel conditions using beacon strength measurements. Data transmission is simply ceased for the infrequent periods when beacon strength falls below an acceptable threshold level e. Since the system is non-real-time and non-continuous, occasional rain fade events have no material effect on the service. For this reason the availability of the raw channel can be much less that that of real-time systems, greatly reducing the size, cost and power of both the space and ground equipment needed to provide the service.
Furthermore the existence of this beacon signal also offers the system an ability to adjust power level, bandwidth, or even closed-loop track the satellite's position to improve antenna pointing accuracy.
The ability to control power levels is especially valuable in conserving battery power on the satellite. The satellite's ability to service a larger number of customer transfers is a function of orbit parameters, but also is limited by an orbit average power budget.
In one embodiment described below, the overall bandwidth capacity is achieved by multiplexing a number e. Should link quality degrade an optional feature would allow all transmit power to be allocated to less channels, thus maintaining a quality link, but at a reduced bandwidth until fade conditions improve. Interference friendly. Since all actions of the system are performed on a pre-determined basis and since the applications are all non-real-time, the system can easily avoid transmitting along pre-designated vectors such as the geostationary arc or ones that would intersect other low earth orbit systems, which would otherwise create signal interference.
No data transfer protocol required. Since the system only supports non-real-time applications, it avoids the usual satellite communications need for a data transfer protocol and the associated return channel. No complex multiple user access scheme required. The system services users sequentially and allocates the full satellite capacity to only one single user at given a time. Therefore, there is no multiple user access scheme employed by the system. This also allows for simple, and cost effective, very high data rate channelization of the bandwidth versus tens or hundreds of individual lower rate channels more typically used by satellite communications systems.
No signal latency issues. The system depicted herein, through its focus on file transfers, principally supports non-real-time applications. Therefore signal latency issues usually found with satellite communications systems that try to support real-time applications such as phone conversations are not applicable.
All actions by the system are pre-determined on the ground. The satellite control facility only has to periodically uplink the scheduled actions and then each satellite executes them as specified. Therefore, the satellite does not have to make an autonomous decision about which customers to serve, or when to serve them, significantly simplifying its design. An optional feature would add a low bandwidth link to the satellite that would allow a user to request data file pick-ups on a non-priority basis.
As implemented, the serial servicing of users under this alternative embodiment may remain, and the decision to accept a new pickup must only insure that this new action does not violate on-board storage limits, violate previously scheduled deliveries, violate the current orbit's power budget, or other criteria. No significant connectivity with terrestrial networks needed.
Many satellite communications systems depend on connectivity with terrestrial communications infrastructure to complete their service. This system operates essentially independent of terrestrial communications infrastructure, moving data directly from the data source to the specified data sink, although the terminus could be a fibre node when desired.
Incremental system growth. Each satellite may operate independent of every other satellite in this system and the system users do not need to be in continuous view of a satellite to be satisfied. Therefore, a large fleet of satellites is not needed to begin the service. The service can begin with a limited number of satellites e. This is in contrast to many other satellite communications systems especially those that utilize non-geostationary orbits NGSO where a large number of satellites have to be completed and on orbit before any users can be supported.
All techniques that are described scale with available technology elements. For example, optical satellite communications can be substituted for radio frequency communications. Also as payload equipment becomes available to support higher bandwidth newer satellites and corresponding ground stations can be used to expand the service data rate capability. The non real-time nature of the embodiment also allows terminals to be constructed at lower cost. Lower orbits permit the use of smaller antennas which are easier to point, and when only one way transfers are required the terminal may be receive or transmit only.
Also the antennas may be pointed using a simplified open loop tracking embodiment in which the antenna pointing is based on a geometric calculation that uses the location and orientation of the terminal as determined for example, by GPS and a compass and the location of the satellite as determined by time from GPS and current ephemeris and orbital elements.
As described below, a digital satellite communications system and data transfer method for the global movement of very large digital data files, ensures high data integrity, with delivery in less than a day.
As shown in FIG. The depicted embodiment of the invention in FIG. The satellites in the fleet are composed of a communications payload and a supporting platform. Each satellite in the fleet has an assigned orbit, with the orbit inclination of the satellites ranging from 60 to 70 degrees. This orbital configuration of the fleet is chosen to meet the required global access. It is noted that a regimented orbital configuration is not necessary.
Other embodiments may place the satellites into an orbital configuration with variations on orbit altitude and inclination, which would also provide significant global coverage, or be optimized around the distribution of customer groups. The overall configuration of the fleet may be that of a single fleet or subdivided to better meet groups of user's requirements including global locations.
Within the embodiment each satellite operates independent of every other satellite in the fleet. Each satellite has its own on-board mass data storage, with no requirement for inter-satellite links or overlapping coverage. As well, the system users do not need to be in continuous view of a satellite to be satisfied. Therefore, a large fleet of satellites is not needed to begin global coverage of the service.
The revised and updated sixth edition of Satellite Communications Systems contains information on the most recent advances related to satellite communications systems, technologies, network architectures and new requirements of services and applications. The authors — noted experts on the topic — cover the state-of-the-art satellite communication systems and technologies and examine the relevant topics concerning communication and network technologies, concepts, techniques and algorithms. New to this edition is information on internetworking with the broadband satellite systems, more intensive coverage of Ka band technologies, GEO high throughput satellite HTS , LEO constellations and the potential to support the current new broadband Internet services as well as future developments for global information infrastructure. Ippolito, Louis J. Rehman, Masood Ur. Fernando, Xavier N.
One of the main features of MIMO is the utilisation of the spatial dimension. The spatial dimension in MIMO brings significant performance improvement through array gain, spatial diversity, spatial multiplexing and interference avoidance. The LOS path is essential in achieving a healthy link budget. However, in a MIMO scenario the LOS nature of the channel and the large range distance in the channel path can increase the spatial correlation between the channel paths. Geometrical optimisation is required to achieve extra spatial degrees of freedom.
PDF | Volume 1 (Analytical Chapters) of the final report of the NASA/NSF Panel Satellite Communications Systems and Technology is For example, the popular DVB-satellitesecond generation (DVB-S2) systems use AMC techniques  and.
This application is a continuation of U. Provisional Patent Application No. Currently excellent digital data transfer services are available in well connected areas where fibre-optic networks and new terrestrial wireless technologies permit the movement of very large volumes of data at very high speeds. However this level of sufficient telecommunications infrastructure is primarily limited to densely populated areas of the world. Existing geostationary earth orbit GEO satellites do provide relatively high data volume transfer services but are inherently limited to specific regions, with coverage typically over or near land only.
There are plenty of differing types and there seem to be Progressively more being included to the cabinets regularly. The excellent news is always that since so many can be obtained, acquiring a single is rather simple. Nowadays, you will find hundreds and Countless free of charge information web-sites around that offer this kind of stuff, so your examine Satellite Communications Systems: Systems, Techniques and Technology Wiley Series in Communication and Distributed Systems er will probably prove useful. This sort of file is the most typical a single made use of and thus, you will be really about to get some terrific use away from proudly owning a single.
This volume presents a modern survey of communication satellite systems. The subjects covered include: commercial systems, military systems, high-powered systems and systems concepts and their applications, multiple access, direct broadcasting and TV networking, the national information grid and communications from deep space. Skip to main content. No Access Table of Contents pp. Repeater for Communications Satellites pp.
Toggle navigation. The revised and updated sixth edition of Satellite Communications Systems contains information on the most recent advances related to satellite communications systems, technologies, network architectures and new requirements of services and applications. The authors - noted experts on the topic - cover the state-of-the-art satellite communication systems and technologies and examine the relevant topics concerning communication and network technologies, concepts, techniques and algorithms.
Your email address will not be published. Required fields are marked *