System and method for transmit power control
A method for operating a user equipment (UE) includes detecting that a beam failure has occurred, and based thereon, transmitting a first beam failure recovery request (BFRR) message at a first transmit power level on a first channel resource in a channel with a transmit power control mechanism configured to set the first transmit power level different from a first non-BFRR transmit power level of a first non-BFRR message transmitted on the first channel resource in the channel.
1. A method for operating a user equipment (UE), the method comprising:
detecting, by the UE, that a beam failure has occurred, and based thereon:
setting, by the UE using a transmit power control mechanism, a first initial beam failure recovery request (BFRR) transmit power level greater than a first initial non-BFRR transmit power level of a first non-BFRR message transmitted on a first channel resource in a channel, and
transmitting, by the UE, a first BFRR message at the first initial BFRR transmit power level on the first channel resource in the channel.
2. The method of claim 1 , further comprising detecting, by the UE, that the first BFRR message was unsuccessfully transmitted, and based thereon:
setting, by the UE using the transmit power control mechanism, a second transmit power level greater than a second non-BFRR transmit power level of a second non-BFRR message transmitted on a second channel resource in the channel; and
transmitting, by the UE, a second BFRR message on the second channel resource at the second transmit power level.
3. The method of claim 2 , wherein the transmit power control mechanism is expressible as
P _BRACH =min{PCMAX( i ), PRTP BRACH +PLc},
where:
PCMAX(i) is a configured maximum UE transmit power level for subframe i of a primary cell, PLc is a downlink pathloss estimate determined by the UE for the primary cell, and PRTP BRACH is expressible as
PRTP BRACH =PIRTP BRACH +Δ P BRACH +(Num_trans BRACH −1)*PowerRampingStep BRACH ,
where:
PIRTP BRACH is a preamble initial received target power for the channel, ΔP BRACH is a preamble format dependent offset value for the channel, Num_trans BRACH is a preamble transmission counter value for the channel, and PowerRampingStep BRACH is a power ramping up step value for the channel.
4. The method of claim 3 , wherein the first channel resource is a beam failure random access channel (BRACH) resource and the channel is a BRACH.
5. The method of claim 3 , wherein PIRTP BRACH is set to a higher value for the first BFRR message than for the first non-BFRR message transmitted on the first channel resource in the channel.
6. The method of claim 3 , wherein ΔP BRACH is set to a higher value for the first BFRR message than for the first non-BFRR message transmitted on the first channel resource in the channel.
7. The method of claim 3 , wherein PowerRampingStep BRACH is set to a higher value for the first BFRR message than for the first non-BFRR message transmitted on the first channel resource in the channel.
8. The method of claim 3 , wherein Num_trans BRACH is equal to one.
9. The method of claim 2 , wherein the transmit power control mechanism is expressible as
P _BRACH=min{PCMAX( i ), PRTP BRACH +PLc},
where PCMAX(i) is a configured UE transmit power level for subframe i of a primary cell, PLc is a downlink pathloss estimate determined by the UE for the primary cell, and PRTP BRACH is expressible as
PRTP BRACH =PIRTP BRACH +Δ P BRACH +Δ BFRR +(Num_trans BRACH −1)*PowerRampingStep BRACH ,
where PIRTP BRACH is a preamble initial received target power for the channel, ΔP BRACH is a preamble format dependent offset value for the channel, Δ BFRR is a BFRR offset that is added for BFRR transmissions and is zero (in dB) for non-BFRR transmissions, Num_trans BRACH is a preamble transmission counter value for the channel, and PowerRampingStep BRACH is a power ramping up step value for the channel.
10. The method of claim 2 , wherein the transmit power control mechanism is expressible as
P T_BFRR =min{PCMAX( i ), P O_BFRR +α BFRR PL +Δ TF +f BFRR (Δ TPC )+10 log M },
where PCMAX(i) is a configured UE transmit power level for subframe i of a primary cell, P O_BFRR is a target received power of a BFRR message, α BFRR is a fractional PL compensation factor of a BFRR message, Δ TF is a modulation and coding scheme (MCS) dependent component, Δ TPC is a closed loop power control component, f BFRR (.) is an accumulation of closed loop power control results for a BFRR message, and M is a bandwidth.
11. The method of claim 10 , wherein the first channel resource is a physical uplink control channel (PUCCH) resource and the channel is a PUCCH.
12. The method of claim 11 , wherein f BFRR (Δ TPC ) is set to zero.
13. The method of claim 11 , wherein f BFRR (Δ TPC ) is set to a previously used f BFRR (Δ TPC ) value for the first non-BFRR message transmitted on the first channel resource in the channel.
14. The method of claim 11 , wherein α BFRR is set to one for the first BFRR message.
15. The method of claim 11 , wherein α BFRR for the first BFRR message is greater than an alternate α used for the first non-BFRR message transmitted on the first channel resource in the channel.
16. The method of claim 1 , wherein the first initial BFRR transmit power level is set to a predetermined value.
17. The method of claim 16 , wherein the predetermined value is equal to a maximum allowed transmission power.
18. A method for operating a device, the method comprising:
setting, by the device using a transmit power control mechanism, an initial preamble received target power (PRTP) for a beam failure recovery request (BFRR) transmission on a channel resource in a channel,
the initial PRTP for the BFRR transmission being greater than an initial PRTP for a non-BFRR message transmitted on the channel resource in the channel, and
the transmit power control mechanism configured to set a transmit power level of the BFRR transmission different from a non-BFRR transmit power level of the non-BFRR message transmitted on the channel resource in the channel; and
indicating, by the device, the initial PRTP for the BFRR transmission to user equipments (UEs).
19. The method of claim 18 , further comprising maintaining, by the device, a first set of power control parameters for BFRR transmissions and a second set of power control parameters for non-BFRR transmissions.
20. The method of claim 19 , further comprising:
indicating, by the device, the first set of power control parameters for BFRR transmissions to UEs in a unicast manner; and
indicating, by the device, the second set of power control parameters for non-BFRR transmissions in a broadcast manner.
21. A user equipment (UE) comprising:
one or more processors; and
a computer readable storage medium storing programming for execution by the one or more processors, the programming including instructions to configure the UE to:
detect a beam failure,
set, using a transmit power control mechanism, a first initial beam failure recovery request (BFRR) transmit power level greater than a first initial non-BFRR transmit power level of a first non-BFRR message transmitted on a first channel resource in a channel, and
transmit a first BFRR message at the first initial BFRR transmit power level on the first channel resource in the channel.
22. The UE of claim 21 , wherein the programming includes instructions to configure the UE to detect that the first BFRR message was unsuccessfully transmitted, and based thereon:
set, using the transmit power control mechanism, a second transmit power level greater than a second non-BFRR transmit power level of a second non-BFRR message transmitted on a second channel resource in the channel; and
transmit a second BFRR message on the second channel resource at the second transmit power level.
23. The UE of claim 22 , wherein the transmit power control mechanism is expressible as
P _BRACH =min{PCMAX( i ), PRTP BRACH +PLc},
where:
PCMAX(i) is a configured maximum UE transmit power level for subframe i of a primary cell, PLc is a downlink pathloss estimate determined by the UE for the primary cell, and PRTP BRACH is expressible as
PRTP BRACH =PIRTP BRACH +ΔP BRACH +(Num_trans BRACH −1)*PowerRampingStep BRACH ,
where:
PIRTP BRACH is a preamble initial received target power for the channel, ΔP BRACH is a preamble format dependent offset value for the channel, Num_trans BRACH is a preamble transmission counter value for the channel, and PowerRampingStep BRACH is a power ramping up step value for the channel.
24. The UE of claim 22 , wherein the transmit power control mechanism is expressible as
P _BRACH =min{PCMAX( i ), PRTP BRACH +PLc},
where PCMAX(i) is a configured UE transmit power level for subframe i of a primary cell, PLc is a downlink pathloss estimate determined by the UE for the primary cell, and PRTP BRACH is expressible as
PRTP BRACH =PIRTP BRACH +ΔP BRACH +Δ BFRR +(Num_trans BRACH −1)*PowerRampingStep BRACH ,
where PIRTP BRACH is a preamble initial received target power for the channel, ΔP BRACH is a preamble format dependent offset value for the channel, ΔBFRR is a BFRR offset that is added for BFRR transmissions and is zero (in dB) for non-BFRR transmissions, Num_trans BRACH is a preamble transmission counter value for the channel, and PowerRampingStep BRACH is a power ramping up step value for the channel.
25. The UE of claim 22 , wherein the transmit power control mechanism is expressible as
P T_BFRR =min{PCMAX( i ), P O_BFRR +α BFRR PL+Δ TF +f BFRR (Δ TPC )+10 log M },
where PCMAX(i) is a configured UE transmit power level for subframe i of a primary cell, P O_BFRR is a target received power of a BFRR message, α BFRR is a fractional PL compensation factor of a BFRR message, Δ TF is a modulation and coding scheme (MCS) dependent component, Δ TPC is a closed loop power control component, f BFRR (.) is an accumulation of closed loop power control results for a BFRR message, and M is a bandwidth.