Frame structure for filter bank multi-carrier (FBMC) waveforms
A unified frame structure for filter bank multi-carrier (FBMC) and orthogonal frequency division multiplexed (OFDM) waveforms may allow FBMC and OFDM frames to be communicated over a common channel without significant inter-frame gaps. The unified frame structure may set an FBMC frame duration to an integer multiple of an OFDM frame element duration to enable alignment of FBMC frames and OFDM frames in the time domain. The unified frame structure may also map control channels in the FBMC and OFDM frames to common resource locations so that the respective control channels are aligned in the time and/or frequency domains. The unified frame structure may also share synchronization channels between FBMC and OFDM frames. Additionally, overhead in an FBMC time division duplexed (TDD) communications channel can be reduced by overlapping time windows appended to FBMC blocks.
1. A method for communicating, the method comprising:
communicating, by a wireless device, a filter bank multi-carrier (FBMC) frame over an air interface of a wireless network, wherein a frame duration of the FBMC frame is an integer multiple of a duration of an orthogonal frequency division multiple access (OFDMA) frame element in an OFDMA frame communicated in the wireless network or in a neighboring wireless network, wherein the OFDMA frame element includes the OFDMA frame, a transmission time interval (TTI) of the OFDMA frame, or a slot in the TTI of the OFDMA frame, and wherein the FBMC frame includes a portion of a time window produced from circularly convolved filtering modulation of an FBMC block carried by an adjoining FBMC frame, the adjoining FBMC frame being communicated consecutively with the FBMC frame in the time domain.
2. The method of claim 1 , wherein the OFDMA frame element comprises the OFDMA frame.
3. The method of claim 1 , wherein the OFDMA frame element comprises the TTI of the OFDMA frame.
4. The method of claim 1 , wherein the OFDMA frame element comprises the slot in the TTI of the OFDMA frame.
5. The method of claim 1 , wherein the FBMC frame includes one or more FBMC blocks, and wherein each of the one or more FBMC blocks include a plurality of FBMC symbols.
6. The method of claim 1 , wherein the FBMC frame includes an FBMC block and at least a portion of a time window produced from circularly convolved filtering modulation of the FBMC block.
7. The method of claim 1 , wherein the FBMC frame includes a control channel, the control channel being mapped to resource locations within the FBMC frame that align with control channels in the OFDMA frame.
8. The method of claim 7 , wherein the control channel is excluded from resource locations within the FBMC frame that align with resource elements (REs) of a physical downlink shared channel (PDSCH) in the OFDMA frame.
9. A wireless device comprising:
a processor; and
a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
communicate a filter bank multi-carrier (FBMC) frame over an air interface of a wireless network, wherein a frame duration of the FBMC frame is an integer multiple of a duration of an orthogonal frequency division multiple access (OFDMA) frame element in an OFDMA frame communicated in the wireless network or in a neighboring wireless network, and wherein the OFDMA frame element includes the OFDMA frame, a transmission time interval (TTI) of the OFDMA frame, or a slot in the TTI of the OFDMA frame, and wherein the FBMC frame includes a portion of a time window produced from circularly convolved filtering modulation of an FBMC block carried by an adjoining FBMC frame, the adjoining FBMC frame being communicated consequently with the FBMC frame in the time domain.
10. A method for reducing overhead in a time division duplexed (TDD) communications session of a wireless network, the method comprising:
detecting, by a wireless transceiver, a first filter bank multi-carrier (FBMC) block over a frequency resource during a first period, the first FBMC block being communicated in a wireless transmission that includes the first FBMC block and a first time window produced from circularly convolved filtering modulation of the first FBMC block; and
transmitting, by the wireless transceiver, an output signal over the frequency resource during a second period, wherein the output signal includes a second FBMC block and a second time window produced from circularly convolved filtering modulation of the second FBMC block, and wherein the second time window produced from circularly convolved filtering modulation of the second FBMC block partially overlaps the first time window produced from circularly convolved filtering modulation of the first FBMC block such that at least a portion of the second time window and a portion of the first time window are communicated over common time-frequency resources.
11. The method of claim 10 , wherein the first period is non-contiguous with the second period.
12. The method of claim 10 , wherein the wireless transceiver is a mobile station in the wireless network.
13. The method of claim 10 , wherein the wireless transceiver is an access point (AP) in the wireless network.
14. The method of claim 10 , wherein the first period precedes the second period in the time domain.
15. The method of claim 10 , wherein the second period precedes the first period in the time domain.
16. The method of claim 11 , wherein the first period and the second period are separated by an intermediate time interval during which time the wireless transceiver is neither detecting nor transmitting radio signals over the frequency subband.
17. The method of claim 16 , wherein the intermediate interval is equal to or greater than a transmission-reception (Tx-Rx) switching time of the wireless transceiver.
18. The method of claim 16 , wherein the intermediate interval is equal to or greater than a propagation time between neighboring access points (APs) in the wireless network.
19. The method of claim 17 , wherein the intermediate interval is equal to or greater than a transmission-reception (Tx-Rx) switching time of a mobile device in the wireless network.
20. A wireless device comprising:
a processor; and
a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
detect a first filter bank multi-carrier (FBMC) block over a frequency resource during a first period, the first FBMC block being communicated in a wireless transmission that includes the first FBMC block and a first time window produced from circularly convolved filtering modulation of the first FBMC block; and
transmit an output signal over the frequency resource during a second period, wherein the output signal includes a second FBMC block and a second time window produced from circularly convolved filtering modulation of the second FBMC block, and
wherein the second time window produced from circularly convolved filtering modulation of the second FBMC block partially overlaps the first time window produced from circularly convolved filtering modulation of the first FBMC block such that at least a portion of the second time window and a portion of the first time window are communicated over common time-frequency resources.