Devices, base stations, and methods for communicating scheduling requests via an underlay control channel in a wireless communication system
Wireless communication systems, base stations, and user equipment are disclosed that enable communication of scheduling requests via an underlay control channel that has an energy below a noise level of the spectrum. The scheduling requests may be sent and received at any time, including during downlink and uplink data communication periods of the base station.
1. A user equipment device, comprising:
at least one processor configured to:
generate a scheduling request (SR) signal and transmit the SR signal to a base station via an underlay control channel below a noise level for a communication spectrum; and
generate data packets and transmit the data packets to the base station over an overlay channel above the noise level for the communication spectrum, the user equipment device configured to transmit the SR signal to the base station via the underlay control channel while the user equipment device is also communicating with the base station via an active band overlay signal.
2. The user equipment device of claim 1 , wherein the user equipment device is configured to not allow communication via the underlay control channel while receiving downlink control information from the base station.
3. The user equipment device of claim 1 , wherein the user equipment device is configured to allow communication via the underlay control channel while transmitting uplink control information to the base station.
4. The user equipment device of claim 1 , wherein the underlay control channel is a multiple access underlay control channel.
5. The user equipment device of claim 1 , wherein the SR signal includes control information related to the data packets to be transmitted by the user equipment device, wherein the control information includes at least one of a buffer status, priority information, power-headroom, and combinations thereof.
6. A base station comprising at least one of one or more transmitters and one or more receivers configured to communicate uplink data and downlink data with one or more user equipments (UEs) using active sub-carriers of a spectrum, and simultaneously communicate scheduling requests with a user equipment (UE) of the one or more UEs using an underlay control channel below a noise level of the spectrum.
7. The base station of claim 6 , wherein the scheduling requests are spread spectrum signals spread across the entire spectrum below the noise level.
8. The base station of claim 6 , wherein the scheduling requests are spread spectrum signals spread below the noise level and across a portion of the spectrum within guard bands outside of the active sub-carriers.
9. The base station of claim 6 , wherein the base station is configured to receive the scheduling requests from the UE without first assigning uplink or downlink resources to the UE.
10. The base station of claim 6 , wherein the base station is configured to communicate the uplink data, the downlink data, and the scheduling requests with the user equipment within a time division duplex (TDD) network or a frequency division duplex (FDD) network.
11. The base station of claim 6 , wherein the base station is further configured to generate and transmit paging messages to the user equipment using the underlay control channel.
12. A method comprising:
sending a scheduling request from a user equipment to a base station via an underlay control channel below a noise level of a spectrum;
receiving the scheduling request by the base station; and
transmitting a scheduling request grant from the base station to the user equipment, wherein receiving the scheduling request and transmitting the scheduling request are performed in parallel with other data communication between the base station and other user equipment.
13. The method of claim 12 , wherein sending the other data communication between the base station and the other user equipment includes downlink data communication and/or uplink data communication between the base station and the other user equipment.
14. The method of claim 13 , wherein the downlink data communication and/or the uplink data communication is transmitted over an overlay channel above the noise level for the spectrum.
15. The method of claim 12 , further comprising:
receiving a plurality of different scheduling requests from different user equipment via the underlay control channel by the base station at different times; and
transmitting scheduling request grants for each of the different scheduling requests to their respective user equipment.
16. The method of claim 12 , wherein sending the scheduling request includes using an on/off keying technique configured to send information from the user equipment to the base station.
17. The method of claim 16 , wherein each information bit sent from the user equipment to the base station includes a distinct spreading gain vector.
18. The method of claim 17 , wherein the spreading gain vector includes a cyclic-shifted ZC-sequence as its spreading sequence.
19. The method of claim 16 , wherein each scheduling request includes a reference bit and multiple bits over a set of non-overlapping ZC sequences per transmitted scheduling request.