Air-to-ground co-channel interference avoidance system
View Patent ↗Techniques to reduce scheduling grants to minimize or eliminate the use of control channels, at the expense of flexibility, allow protection of the system from unnecessary retransmissions in case of interference from the primary system. Use of a single grant to allocate a set of resources across all carriers, or communication channels simplifies the system at the cost of retransmission of a grant for all carriers in the case if interference corrupts the transmission of a subset of the carriers. Thus, complementing a single grant embodiment with detection of the affected frequency carriers or victim carriers and remove such carriers from the carrier aggregation configuration allows more efficient use of the allocated spectrum.
1. An air-to-ground communication system comprising:
a transceiver unit disposed within a ground station included in the air-to-ground communication system, the transceiver unit utilized by the air-to-ground communication system to communicate on a plurality of carriers, each carrier of the plurality of carriers being a different, respective communication channel corresponding to a different, respective frequency of a frequency spectrum utilized by the plurality of carriers, the air-to-ground communication system being a secondary user of the frequency spectrum utilized by the plurality of carriers, the secondary user utilizing the frequency spectrum to provide air-to-ground communications, and the secondary user being subject to one or more restrictions on at least one of power or spatial configuration to thereby allow co-presence of the primary user and the secondary user on the frequency spectrum, wherein the plurality of carriers is configured by the secondary user via grants communicated over a control channel; and
a computer processor coupled to the transceiver unit and configured to:
cause the transceiver unit to communicate, over the control channel, a first transmission grant indicating two or more of the plurality of carriers allocated to the transceiver unit to utilize for sending transmissions;
cause the transceiver unit to transmit, in accordance with the one or more restrictions and with the first transmission grant communicated by the transceiver unit, data on the indicated two or more of the plurality of carriers;
configure the transceiver unit to detect a transmission failure indicating that the transmitted data on a particular carrier of the two or more of the plurality of carriers has not been received by a receiving unit; and
in response to detecting the transmission failure:
cause the transceiver unit to communicate, over the control channel, a retransmission grant excluding an indication of the particular carrier and including an indication of the other carriers of the two or more of the plurality of carriers indicated by the first transmission grant, and
cause the transceiver unit to retransmit, to the receiving unit, in accordance with the one or more restrictions and with the retransmission grant communicated by the transceiver unit, the data on the two or more of the plurality of carriers.
2. The air-to-ground communication system of claim 1 , wherein the transceiver unit is configured to operate in accordance with the one or more restrictions to which the secondary user is subjected on at least one of the plurality of carriers.
3. The air-to-ground communication system of claim 1 , wherein the transceiver unit is configured to allow the primary user to transmit and receive on at least one of the plurality of carriers co-presently with the transceiver unit transmitting on the at least one of the plurality of carriers.
4. The air-to-ground communication system of claim 3 , wherein the primary user comprises a satellite communication system.
5. The air-to-ground communication system of claim 1 , wherein the air-to-ground communications comprise a digital modulation service and wherein the transceiver unit is configured to operate in accordance with the one or more restrictions to which the secondary user is subjected within at least one of the plurality of carriers using the digital modulation service.
6. The air-to-ground communication system of claim 1 , wherein the computer processor is configured to cause the transceiver unit to monitor the two or more of the plurality of carriers for at least one source of interference by measuring a block error ratio (BLER) associated with the air-to-ground communications.
7. The air-to-ground communication system of claim 1 , wherein the computer processor is configured to cause the transceiver unit to monitor the two or more of the plurality of carriers during a guard time of a time division duplex (TDD) communication protocol for the presence of at least one signal transmitted by the primary user.
8. The air-to-ground communication system of claim 1 , wherein the computer processor is configured to cause the transceiver unit to avoid at least one source of interference by recording the carrier associated with the interference in a computer memory, and wherein the computer processor is configured to cause the transceiver to transmit the data on the other carriers of the two or more of the plurality of carriers.
9. The air-to-ground communication system of claim 1 , wherein, to detect a transmission failure, the computer processor is configured to cause the transceiver unit to receive at least two acknowledgement signals associated with the two or more of the plurality of carriers,
wherein the computer processor is configured to record in a computer memory the absence of the acknowledgement on the particular carrier of the two or more of the plurality of carriers as indicating the presence of interference on the particular carrier, and
wherein the computer processor is configured to record in the computer memory the absence of two of the acknowledgements as indicating the presence of environmental interference.
10. A method, performed by a computer processor, comprising:
configuring a transceiver unit to be utilized by an air-to-ground communication system to communicate on a plurality of carriers, the transceiver unit disposed within a ground station included in the air-to-ground communications system, each carrier of the plurality of carriers being a different, respective communication channel corresponding to a different, respective frequency of a frequency spectrum utilized by the plurality of carriers, the air-to-ground communication system being a secondary user of the frequency spectrum utilized by the plurality of carriers, the secondary user utilizing the frequency spectrum to provide air-to-ground communications, and the secondary user being subject to one or more restrictions on at least one of power or spatial configuration to thereby allow co-presence of the primary user and the secondary user on the frequency spectrum, wherein the plurality of carriers is configured by the secondary user using grants communicated over a control channel, and wherein at least one of the communication services comprises a guard time where the transceiver unit halts transmission;
causing the transceiver unit to communicate, over the control channel, a first transmission grant indicating two or more of the plurality of carriers allocated to the transceiver unit to utilize for sending transmissions;
causing the transceiver unit to transmit, in accordance with the one or more restrictions and with the first transmission grant communicated by the transceiver unit, data on the indicated two or more of the plurality of carriers;
configuring the transceiver unit to detect a transmission failure indicating that the transmitted data on a particular carrier of the two or more of the plurality of carriers has not been received by a receiving unit; and
in response to detecting the transmission failure:
causing the transceiver unit to communicate, over the control channel, a retransmission grant excluding an indication of the particular carrier and including an indication of the other carriers of the two or more of the plurality of carriers indicated by the first transmission grant, and
causing the transceiver unit to retransmit, to the receiving unit, in accordance with the one or more restrictions and with the retransmission grant communicated by the transceiver unit, the data on the two or more of the plurality of carriers.
11. The method of claim 10 , wherein the transceiver unit is configured to operate in accordance with the one or more restrictions to which the secondary user is subjected on at least one of the plurality of carriers.
12. The method of claim 10 , wherein the transceiver unit is configured to allow the primary user to transmit and receive on at least one of the plurality of carriers co-presently with the transceiver unit transmitting on the at least one of the plurality of carriers.
13. The method of claim 12 , wherein the primary user comprises a satellite communication system.
14. The method of claim 10 , wherein the air-to-ground communications comprise a digital communication service, and wherein the transceiver unit is configured to operate in accordance with the one or more restrictions to which the secondary user is subjected within at least one of the plurality of carriers to provide the digital communication service.
15. The method of claim 10 , comprising configuring the transceiver unit to monitor the two or more of the plurality of carriers for at least one source of interference by measuring a block error ratio (BLER) associated with the air-to-ground communications.
16. The method of claim 10 , comprising configuring the transceiver unit to monitor the two or more of the plurality of carriers during the guard time of a time division duplex (TDD) digital communications protocol for the presence of at least one signal transmitted by the primary user.
17. The method of claim 10 , comprising:
configuring the transceiver to avoid at least one source of interference by recording the carrier associated with the interference in a computer memory, and
configuring the transceiver to transmit the data on the other carriers of the two or more of the plurality of carriers.
18. The method of claim 10 , wherein detecting the transmission failure comprises:
configuring the transceiver unit to receive at least two acknowledgement signals associated with the two or more of the plurality of carriers,
recording in a computer memory the absence of the acknowledgement on the particular carrier of the two or more of the plurality of carriers as indicating the presence of interference on the particular carrier, and
recording in the computer memory the absence of two of the acknowledgements as indicating the presence of environmental interference.
19. The method of claim 10 , wherein at least one of the plurality of carriers is shared with a Ku band satellite service.
20. The method of claim 17 , comprising:
retrieving from the computer memory the carrier associated with the interference,
configuring the transceiver unit to monitor the carrier for the absence of transmissions from a primary user of the carrier, and
configuring the transceiver to resume transmitting and receiving data on the carrier in the absence of transmissions from the primary user of the carrier.
21. The air-to-ground communication system of claim 1 , wherein the detection of the transmission failure indicating that the transmitted data on the particular carrier of the two or more of the plurality of carriers has not been received comprises at least one of the following:
a detection of an error in the transmitted data on the particular carrier, or
a detection of an interfering signal on the particular carrier.
22. The method of claim 10 , wherein configuring the transceiver unit to detect the transmission failure indicating that the transmitted data on the particular carrier of the two or more of the plurality of carriers has not been received comprises at least one of the following:
configuring the transceiver unit to detect an error in the transmitted data on the particular carrier, or
configuring the transceiver unit to detect an interfering signal on the particular carrier.