Systems and methods for lane management in a communication bus
Systems and method for lane management in a communication bus are disclosed. In one aspects, a communication link or bus between a baseband processor (BBP) and a radio frequency integrated circuit (RFIC) may include multiple uplink lanes for transmission and multiple downlink lanes for reception that are frequency constrained and adjust bandwidth by adjusting duty cycles on the lanes. To reduce power consumption by the communication bus, exemplary aspects of the present disclosure contemplate using in-band signaling to turn off lanes selectively during inactive periods such that the lanes do not duty cycle in tandem with active lanes. Additionally, in some aspects, the uplink lanes may be continuously active during transmission while the downlink lanes are turned off. This dynamic lane usage reduces power consumption, does not require additional pins for sideband signaling, and does not introduce any additional latency.
1. A baseband processor (BBP) comprising:
a bus interface configured to couple to a communication bus, the bus interface comprising:
one or more uplink lanes; and
one or more downlink lanes; and
a control circuit coupled to the bus interface and configured to:
adjust a bandwidth for the communication bus by changing a duty cycle associated with the communication bus; and
while the communication bus is active:
cycle the one or more downlink lanes on and off during a receive slot; and
turn on at least one of the one or more uplink lanes on during an entirety of a transmit slot.
2. The BBP of claim 1 , wherein the control circuit is further configured to turn off at least one of the one or more uplink lanes during the receive slot.
3. The BBP of claim 1 , wherein the control circuit is configured to send data to a radio frequency integrated circuit (RFIC) over the communication bus.
4. The BBP of claim 3 , wherein the control circuit is configured to send control signals to the RFIC over a radio frequency front end (RFFE) bus distinct from the communication bus.
5. The BBP of claim 1 , wherein a duty cycle for a receive slot is greater than a second duty cycle for the transmit slot.
6. The BBP of claim 1 , wherein the receive slot is time division duplexed (TDD).
7. The BBP of claim 1 , wherein the receive slot is frequency division duplexed (FDD).
8. The BBP of claim 1 , wherein the control circuit is further configured to cycle at least one of the uplink lanes on and off during the receive slot concurrently.
9. The BBP of claim 8 , wherein the control circuit is further configured to send in-band signals on the at least one uplink lane during the receive slot.
10. The BBP of claim 1 , wherein the control circuit is further configured to leave at least one downlink on during the transmit slot.
11. The BBP of claim 10 , wherein the control circuit is further configured to send in-band signals on the at least one downlink lane during the transmit slot.
12. A radio frequency integrated circuit (RFIC) comprising:
a bus interface configured to couple to a communication bus, the bus interface comprising:
a plurality of uplink lanes; and
a plurality of downlink lanes;
a buffer; and
a control circuit coupled to the bus interface and configured to:
adjust a bandwidth for the communication bus by changing a duty cycle associated with the communication bus;
while the communication bus is inactive, buffer data from an antenna in the buffer; and
while the communication bus is active:
cycle the one or more downlink lanes on and off during a receive slot; and
turn on at least one of the one or more uplink lanes on during an entirety of a transmit slot.
13. The RFIC of claim 12 , further comprising a plurality of readers associated with the uplink lanes; and
wherein the control circuit is further configured to send a change notice on a downlink lane response to a signal from the plurality of readers.
14. The RFIC of claim 12 , wherein the buffer is coupled to each of the plurality of downlink lanes.
15. The RFIC of claim 12 , wherein the bus interface further comprises a clock lane configured to receive a clock signal from a baseband processor.
16. A method of controlling a communication bus, the method comprising:
adjusting a receive bandwidth for the communication bus by adjusting a receive duty cycle;
while in a receive slot, turning off at least one uplink lane being conveyed on the communication bus; and
while in a transmit slot, leaving all uplink lanes on for a duration of the transmit slot, wherein all uplink lanes are conveyed on the communication bus.
17. The method of claim 16 , further comprising, while in the receive slot, providing in-band commands on a downlink lane.
18. The method of claim 16 , further comprising, while in the transmit slot, providing in-band commands on an uplink lane.
19. The method of claim 16 , further comprising using time division duplexing for signals on the communication bus.
20. The method of claim 16 , further comprising using frequency division duplexing for signals on the communication bus.