Telecommunications – Carrier wave repeater or relay system – Portable or mobile repeater
Reexamination Certificate
2002-02-12
2004-01-27
Maung, Nay (Department: 2684)
Telecommunications
Carrier wave repeater or relay system
Portable or mobile repeater
C455S013100, C455S427000, C455S063300
Reexamination Certificate
active
06684057
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to radiotelephone communications systems and methods, and more particularly to terrestrial cellular and satellite cellular radiotelephone communications systems and methods.
BACKGROUND OF THE INVENTION
Satellite radiotelephone communications systems and methods are widely used for radiotelephone communications. Satellite radiotelephone communications systems and methods generally employ at least one space-based component, such as one or more satellites that are configured to wirelessly communicate with a plurality of satellite radiotelephones.
A satellite radiotelephone communications system or method may utilize a single antenna beam covering an entire area served by the system. Alternatively, in cellular satellite radiotelephone communications systems and methods, multiple beams are provided, each of which can serve distinct geographical areas in the overall service region, to collectively serve an overall satellite footprint. Thus, a cellular architecture similar to that used in conventional terrestrial cellular radiotelephone systems and methods can be implemented in cellular satellite-based systems and methods. The satellite typically communicates with radiotelephones over a bidirectional communications pathway, with radiotelephone communication signals being communicated from the satellite to the radiotelephone over a downlink or forward link, and from the radiotelephone to the satellite over an uplink or return link.
The overall design and operation of cellular satellite radiotelephone systems and methods are well known to those having skill in the art, and need not be described further herein. Moreover, as used herein, the term “radiotelephone” includes cellular and/or satellite radiotelephones with or without a multi-line display; Personal Communications System (PCS) terminals that may combine a radiotelephone with data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and a pager, Internet/intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) receiver; and/or conventional laptop and/or palmtop computers or other appliances, which include a radio frequency transceiver.
Terrestrial networks can enhance cellular satellite radiotelephone system availability, efficiency and/or economic viability by terrestrially reusing at least some of the frequency bands that are allocated to cellular satellite radiotelephone systems. In particular, it is known that it may be difficult for cellular satellite radiotelephone systems to reliably serve densely populated areas, because the satellite signal may be blocked by high-rise structures and/or may not penetrate into buildings. As a result, the satellite spectrum may be underutilized or unutilized in such areas. The use of terrestrial retransmission can reduce or eliminate this problem.
Moreover, the capacity of the overall system can be increased significantly by the introduction of terrestrial retransmission, since terrestrial frequency reuse can be much denser than that of a satellite-only system. In fact, capacity can be enhanced where it may be mostly needed, i.e., densely populated urban/industrial/commercial areas. As a result, the overall system can become much more economically viable, as it may be able to serve a much larger subscriber base. Finally, satellite radiotelephones for a satellite radiotelephone system having a terrestrial component within the same satellite frequency band and using substantially the same air interface for both terrestrial and satellite communications can be more cost effective and/or aesthetically appealing. Conventional dual band/dual mode alternatives, such as the well known Thuraya, Iridium and/or Globalstar dual mode satellite/terrestrial radiotelephone systems, may duplicate some components, which may lead to increased cost, size and/or weight of the radiotelephone.
One example of terrestrial reuse of satellite frequencies is described in U.S. Pat. No. 5,937,332 to the present inventor Karabinis entitled Satellite Telecommunications Repeaters and Retransmission Methods, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein. As described therein, satellite telecommunications repeaters are provided which receive, amplify, and locally retransmit the downlink signal received from a satellite thereby increasing the effective downlink margin in the vicinity of the satellite telecommunications repeaters and allowing an increase in the penetration of uplink and downlink signals into buildings, foliage, transportation vehicles, and other objects which can reduce link margin. Both portable and non-portable repeaters are provided. See the abstract of U.S. Pat. No. 5,937,332.
In view of the above discussion, there continues to be a need for systems and methods for terrestrial reuse of cellular satellite frequencies that can allow improved reliability, capacity, cost effectiveness and/or aesthetic appeal for cellular satellite radiotelephone systems, methods and/or satellite radiotelephones.
SUMMARY OF THE INVENTION
Some embodiments of the present invention allow a satellite radiotelephone frequency to be reused terrestrially within the same satellite cell, while allowing intra-system interference to be reduced. In particular, some of these embodiments include a space-based component, such as a satellite, that is configured to receive wireless communications from a first radiotelephone in a satellite footprint, comprising one or more cells, over a satellite radiotelephone frequency band. An ancillary terrestrial network, comprising one or more ancillary terrestrial components, is configured to receive wireless communications from a second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band. The space-based component also receives the wireless communications from the second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band as interference, along with the wireless communications that are received from the first radiotelephone in the satellite footprint over the satellite radiotelephone frequency band. An interference reducer is responsive to the space-based component and to the ancillary terrestrial network, and is configured to reduce the interference from the wireless communications that are received by the space-based component from the second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from the second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band.
In other embodiments, the ancillary terrestrial network is closer to the first and second radiotelephones than is the space-based component, such that the wireless communications from the second radiotelephone are received by the ancillary terrestrial network prior to being received by the space-based component. In these embodiments, the interference reducer is configured to generate at least one delayed replica of the wireless communications from the second radiotelephone that are received by the ancillary terrestrial network and to subtract the delayed replica of the wireless communications from the second radiotelephone that are received by the ancillary terrestrial network, from the wireless communications that are received from the space-based component. Adaptive interference-canceling techniques, for example Least Mean Squared Error (LMSE), Kalman, zero-forcing and/or various variations thereof, can be used to update the coefficients of transversal filters to provide adaptive interference reduction. Thus, an entire band of satellite frequencies may be reused terrestrially within any given satellite cell, according to these embodiments of the invention.
Other embodiments of the invention can provide a reconfigurable (multiple-mode) ancillary terrestrial component, t
Maung Nay
Mobile Satellite Ventures LP
Orgad Edan
LandOfFree
Systems and methods for terrestrial reuse of cellular... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Systems and methods for terrestrial reuse of cellular..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Systems and methods for terrestrial reuse of cellular... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3212338