Sounding reference signal switching system
Apparatus and methods for sounding reference signal (SRS) switching are provided. In certain embodiments, a controller internal to the power amplifier module initiates a sequence of instructions, in response to a single command, that cause the antenna switch to actuate for transmission of the sounding reference signal symbol to a second antenna. The user equipment notifies the base station associated with the mobile device to withhold blanking symbols before and after a sounding reference signal symbol.
1. A method of antenna swapping without blanking symbols in a mobile device, the method comprising:
transmitting a sequence of data symbols through a power amplifier and antenna switch to a first antenna, the power amplifier residing in a first module of the mobile device; and
with circuitry of the first module, in response to receiving a command from a component that is external to the first module, initiating an ordered-list of events internal to the first module that: 1) cause the power amplifier to enter a protective mode, 2) cause the antenna switch to actuate from connection to the first antenna to connection to a second antenna, and 3) cause the power amplifier to return to a normal operating mode; and
transmitting a sequence of data symbols through the power amplifier and antenna switch to the second antenna after completion of execution of the ordered-list of events, execution of the ordered-list of events allowing for antenna swapping without blanking symbols.
2. The method of claim 1 wherein the ordered-list of events includes initiating a delay using delay circuitry of the first module, thereby causing switching the antenna switch from the first antenna to the second antenna to occur after the delay.
3. The method of claim 2 wherein in the protective mode a bias of the power amplifier is reduced.
4. The method of claim 2 wherein in the protective mode the power amplifier is in a low power mode.
5. The method of claim 1 wherein the antenna switch actuation occurs between the data symbols of the sequence of data symbols.
6. The method of claim 1 wherein the antenna switch actuation occurs during transmission of a cyclic prefix associated with a sounding reference signal symbol.
7. A mobile device comprising:
a baseband system configured to generate a first sequence of symbols for transmission over a first antenna and a second sequence of symbols for transmission over a second antenna and to output a command for initiating antenna swapping; and
a front end module including an interface configured to be coupled to the baseband system, a power amplifier, and an antenna switch configured to receive an amplified radio frequency signal from the power amplifier, the interface configured, in response to the command being received by the front end module, and after transmission of the first sequence of symbols through the power amplifier and the antenna switch to the first antenna, to: 1) cause the power amplifier to enter a protective mode, 2) cause the antenna switch to switch between the first antenna and the second antenna, and 3) cause the power amplifier to return to a normal operating mode prior to transmission of the second sequence of symbols through the power amplifier and the antenna switch to the second antenna.
8. The mobile device of claim 7 wherein the front end module includes a power amplifier module and a switch module and the interface includes a power amplifier controller and a switch controller.
9. The mobile device of claim 8 wherein the power amplifier module includes the power amplifier and the power amplifier controller, wherein the power amplifier controller is configured to control gain of the power amplifier.
10. The mobile device of claim 8 wherein the switch module includes the antenna switch and the switch controller, wherein the switch controller is configured to control timing of the switching of the antenna switch.
11. The mobile device of claim 7 wherein the interface is a mobile industry processor interface.
12. The mobile device of claim 7 wherein the antenna switch makes connection with the second antenna before breaking a connection with the first antenna during the antenna switch actuation.
13. The mobile device of claim 7 wherein gain of the power amplifier is reduced in the protective mode.
14. The mobile device of claim 13 wherein the power amplifier is placed in an off mode in the protective mode.
15. The mobile device of claim 13 wherein one or more amplifying stages of the power amplifier are shunted in the protective mode.
16. A radio frequency module comprising:
a power amplifier;
a controller; and
an antenna switch configured to provide an amplified radio frequency signal from the power amplifier to a first antenna and switch from the first antenna to a second antenna for transmission of a sounding reference signal symbol, the controller configured, in response to receiving a command from a component external to the radio frequency module, and after transmission of one or more symbols through the power amplifier and the antenna switch to the first antenna, to: 1) cause a the power amplifier to enter a protective mode, 2) cause the antenna switch to perform antenna swapping to switch from the first antenna to the second antenna, and 3) cause the power amplifier to return to a normal operating mode prior to transmission of the sounding reference symbol signal over the second antenna.
17. The mobile device of claim 16 wherein the antenna swapping is performed during transmission of a cyclic prefix of the sounding reference signal symbol.
18. The mobile device of claim 16 wherein the controller initiates a self-sequenced mode responsive to receipt of the command.
19. The mobile device of claim 16 wherein the self-sequenced mode includes commands to cause reduction in gain of the power amplifier, initiation of a delay, and antenna swapping after the delay.
20. The mobile device of claim 16 wherein the controller implements a mobile industry processor interface.