V. BRIEF DESCRIPTION OF THE DRAWINGS
The above set forth and other features of the invention are made more apparent in the ensuing Detailed Description of the Invention when read in conjunction with the attached drawings, wherein:
FIG. 1 illustrates an integrated MSS/ATC.
FIG. 2 illustrates an MSS/ATC system in a LEO constellation.
FIG. 3 illustrates improvement in MSS area.
FIG. 4A illustrates a transmission frequency determined for transceiver 2 (100) for transmission to transceiver 1 (200).
FIG. 4B illustrates the determination of a transmission frequency for transceiver 1 (200) for transmission to transceiver 2 (100).
VI. DETAILED DESCRIPTION OF THE INVENTION
The system of the instant invention, which is set out above in precise and accurate terms so as to enable one of ordinary skill in the art to practice same, will be better understood with reference to the following examples:
Example 1
An example application of FIG. 4A is one where transceiver 1 is at the gateway of a satellite system such as the Globalstar® system, and transceiver 2 in the figure is at the user terminal of an MSS user. Here the gateway transceiver measures, with a spectrum analyzer, the power levels in each frequency channel that it is receiving. These measurements, or a summary of these measurements, are then sent to the user terminal (transceiver 2) which then decides to transmit on a frequency that has the least interference power as reported by the gateway in its summary of measurements. In this way, the user terminal is able to transmit with low power since it is using a relatively clear channel to transmit on. When applied to multiple user terminals, this results in all these users from transmitting at the lowest power in the best channels; i.e., the ones with the least interference.
Example 2
Another application of FIG. 4, which is described in FIG. 4B, would be similar to Example 1, with the difference that in this case the gateway makes the decision itself on what frequency is best for the user terminal to transmit on and merely sends this information on a control channel to the user terminal.
Example 3
Another application of FIG. 4B is similar to Example 2 above in that the gateway measures power or signal-to-noise ratio or bit-error-rate in different frequency channels, decides that all frequency channels are running close to their capacity limit, and then directs the user terminal (transceiver 2) to go to the ATC component rather than the satellite component. In a system like Globalstar®, this is possible because the radiation in all frequencies, ATC or not, from user terminals in a satellite beam, are transmitted through the satellite and received at the gateway. Thus, the gateway is in a good position to look at all the interference presented from all sources (ATC as well as MSS) and determine which frequency, if any, is available for MSS and, if none is available, to direct the user terminal to switch to ATC mode. Likewise, when the gateway senses that any one of the channels becomes available due to some of its traffic being decreased, it can send a control message to the user terminal directing it to go from ATC mode to satellite (MSS) mode.
FIG. 1 shows an integrated MSS/ATC system conceptually. In this system, a user terminal can be operated in either ATC mode or MSS mode. In the Figure, user terminal (1) is shown as operating in ATC mode; i.e., communicating to and from an ATC base station (2). User terminal (3) is shown as operating in MSS mode. In this mode, the user terminal transmits to and receives from a gateway (5) via satellite (4). Satellite (4) may be a GEO satellite, or one of a constellation of GEO or MEO or LEO satellites. The ATC base station potentially interferes with the MSS downlink/uplink inside the ATC coverage area (6).
FIG. 2 shows an example of an MSS/ATC system that uses a LEO constellation of satellites, some of which are shown as (11), (12), (13), (14), (15), (16). In this figure, the darker shaded zones (e.g., zone 17) show normal full-spectrum MSS beams that are using all the MSS frequency channels available. The lighter shaded zones (e.g., zone 18) show regions where worst case ATC frequency interference causes impaired MSS service in frequencies used for ATC.
FIG. 3 shows the same regions, but now with an improvement in MSS area by assigning two separate frequencies dynamically to MSS and ATC segments. In this figure, zones 20 use selected MSS frequencies via selected satellites. Separate ATC frequencies are designated by dotted zones 30.
FIG. 4A shows a transmission frequency determined for transceiver 2 (100) for transmission to transceiver 1 (200). In this case, receiver 1 makes measurements on the signal it receives in various frequency channels from transmitter 2 and sends these measurements to receiver 2 which decides what frequency is best (least interference) for transmitter 2 to transmit on.
FIG. 4B shows the determination of a transmission frequency for transceiver 1 (200) for transmission to transceiver 2 (100). Here receiver 2 makes measurements on the signal it receives in various frequency channels from transmitter 1, and uses these measurements to decide what frequency is best (least interference) for transmitter 1 to transmit on, and then sends this information about this best frequency to transceiver 1.
While the present invention has been particularly described with respect to certain components in its preferred embodiment, it will be understood that the invention is not limited to these particular components described in the preferred embodiments, or the sequence in employing or methods of processing the components. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention defined by the appended claims.
In addition, other components may be employed in the system of the instant invention as claimed as well as variations and alternatives to the components disclosed and claimed with similar results with regard to the operation and function of the system of the instant invention. In particular, the scope of the invention is intended to include, for example, GEO satellites equipped with dynamic beam forming which further enhances the performance of the system, or equipped with a Digital proCessing Router (DCR) or employing virtual gateway techniques as set out in U.S. Pat. No. 6,735,440, especially in FIGS. 15B-C.