1. Field
The present disclosure is directed to a method and apparatus for transmitting a Physical Uplink Control Channel (PUCCH) with a lower Additional Maximum Power Reduction (A-MPR).
2. Introduction
Presently, wireless communication devices, otherwise known as User Equipment (UE), such as smartphones, laptop computers, wireless terminals, and other wireless communication devices, communicate with other communication devices using wireless signals. To communicate over a wireless network, the wireless communication devices use control channels to signal channel information. For example, a Physical Uplink Control Channel (PUCCH) is used to carry uplink control information from a wireless communication device to a wireless communication station, such as a base station, an enhanced NodeB (eNB), an access point, or other wireless communication station that connects the wireless communication device with at least one network, the Internet, and other communication devices.
There is a problem with PUCCH operation for a network supporting intra-band contiguous Carrier Aggregation (CA) where more than one carrier is aggregated together in a contiguous frequency spectrum to increase data throughput. When transmitting on an uplink to a base station, a UE uses an Additional Maximum Power Reduction (A-MPR) to reduce the allowed minimum value of its maximum output power. Different regions in the transmission spectrum provide for different A-MPR. The issue is that that a 0 dB A-MPR region, such as a low A-MPR region, is different depending on whether the UE is configured for single Component Carrier (CC) operation or if the UE is configured for CA. As a consequence, a network operator may not be able to over-provision the PUCCH region, such as reassign the Resource Blocks (RB's) allocated for the PUCCH region, enough to allow 0 dB of A-MPR for a UE configured for CA. Furthermore, the A-MPR for Resource Blocks (RB's) in the PUCCH may be very asymmetric, with the RB nearest to the edge of the aggregated spectrum requiring very large A-MPR while the RB near the center of the aggregated spectrum may require no A-MPR at all. With the current specification, both RB's are allowed to use the maximum of the two A-MPR values.
As mentioned above, the existing solution for single CC is to over-provision the PUCCH, such as adjust the PUCCH region, so that the PUCCH RB pair is in a frequency region with 0 or small A-MPR. For a UE configured for CA, it will not in general be possible to over-provision the PUCCH sufficiently to have 0 dB A-MPR since the location of the UE local oscillator is in the middle of the aggregated spectrum. Furthermore, the operator may not wish to configure the PUCCH region for the needs of the CA UE over the needs of the non-CA UE's.
Thus, there is a need for a method and apparatus for transmitting a PUCCH with a lower A-MPR.