Patent Application
20080076463
The present invention is herein described with reference to the accompanying drawings. The drawings depict embodiments of the present invention for purposes of illustration only.
The present invention relates to a method for operating two-way communications service stations, and particularly to a method for operating a mobile wireless station having a prescribed maximum transmitter power and spurious emission limits. More particularly, the invention relates to a method for operating a mobile wireless station at a higher power level than would be normally allowed but still maintaining a minimum S/N ratio of the broadcast receiver.
The assumption for the present invention is that the one-way broadcast service is using frequency allocations within the tuning range of the two-way communications service transceiver. In normal operation, the receiver section of the communications service periodically tunes across its band of operation to detect which base station has the best signal quality. While the two-way communications transceiver is tuning across its frequency band of operation, it also tunes to frequency channels that are being used for one-way broadcasting. The present invention proposes that the communications transceiver maps the frequencies of strong broadcast signals along with frequencies of base stations of the communications network.
Broadcast signals can be distinguished from two-way communications signals due to the following characteristics. 1) Unique frequencies only are used for broadcasting. For example, the DARS terrestrial repeater frequencies are only used for broadcasting. 2) In frequency bands where time division duplexing is used for communications services, channels with broadcasting signals will have a steady power output while communications signals will have a distinctive on/off characteristic as the source of the signal alternates between transmitting and receiving modes. For example, mobile WiMAX signals have a distinctive on off characteristic with a 5 ms period while digital television signals will have a relatively constant power output.
The flow diagrams of
Based on the received broadcast signal level, the communications service subscriber station assumes that broadcast receivers are close enough to be affected by the two-way communications service station transmitter are also receiving a similar signal level. The next step is to detect whether the power level of the present signals is above a predetermined power level on frequencies known to be used by terrestrial broadcast station transmitters as summarized in step 203.
If the power level of the broadcast signal is above a predetermined level, the maximum output power limit or cap for the two-way communications transceiver is increased to a higher power level than would be allowed which is summarized in step 205. The maximum transmitter power and spurious emissions limit for the communications service transmitter is then increased to a higher power level in proportion to the received broadcast signal levels. Here, the higher power level and corresponding more related out-of-band emissions limit are predetermined by experiments and analysis that show that the broadcast receivers are less susceptible to interference when the broadcast signal is above a threshold received power level.
Two-way communications services and one-way broadcast services are currently mixed together in the following frequency bands in the United States; 470-806 MHz, 2305-2360 MHz, and 2496-2690 MHz. Current FCC regulations allow the 2.3 GHz WCS and 2.5 GHz BRS/EBS emissions limits to be modified by private contractual agreement. In theory, broadcast services in these bands could lease their excess S/N ratio to communications services on adjacent frequency allocations. The communications services could use these contractually relaxed emissions limits to operate subscriber station transmitters at higher power levels than would normally be allowed. Thus, the present invention allows the subscriber station to automatically detect the presence of a strong broadcast signal and select more relaxed transmitter power and spurious emissions limits.
One application of this invention would be to design a 2.3 GHz WCS band communications transceiver that periodically checks for the presence of signals above a predetermined power level on frequencies known only to be used for terrestrial repeater broadcast transmitters. If broadcast signals above a predetermined power level are detected, the maximum power output limit for that transceiver is raised to a higher power level than would be allowed. The higher power level and corresponding more relaxed out-of-band emissions limit are predetermined by experiments and analysis that show that the DARS broadcast receivers are less susceptible to interference when a terrestrial repeater broadcast signal is above a threshold received power level.
As mentioned above, current FCC regulations allow the 2.3 GHz WCS and 2.5 GHz BRS/EBS emissions limits to be modified by private contractual agreement. For example, shown below is an exemplary emissions limit clause for 2.3 GHz WCS private contract: “(10) The out-of-band emissions limits in paragraphs (a)(1) through (a) (9) of this section may be modified by the private contractual agreement of all affected licensees, who shall maintain a copy of the agreement in their station files and disclose it to prospective assignees or transferees and, upon request, to the Commission.”
Also, shown below is an exemplary emissions limit clause for 2.5 GHz EBS/BRS private contract: “(7) Alternative out of band emission limit. Licensees in this service may establish an alternative out of band emission limit to be used at specified band edge(s) in specified geographical areas, in lieu of that set forth in this section, pursuant to a private contractual arrangement of all affected licensees and applicants. In this event, each party to such contract shall maintain a copy of the contract in their station files and disclose it to prospective assignees or transferees and, upon request, to the FCC.”
Although the invention is illustrated and described herein as embodied in a method for operating two-way communication station at a higher power level than would be allowed if a nearby broadcast signal is not present, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The foregoing discussion discloses and describes merely exemplary methods and embodiments of the present invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure, as set forth in the following claims.
This application claims the benefits of U.S. Provisional Application Ser. No. 60/847,183, which was filed on Sep. 26, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60847183 | Sep 2006 | US |
