BACKGROUND

Coordinated multipoint transmission (CoMP) for Long Term Evolution (LTE) wireless systems refers to a family of schemes involving coordination between multiple geographically separated points of the network for communications with user equipment (UE) (or wireless transmit/receive unit (WTRU)). In the uplink direction, CoMP can involve joint reception of the transmitted signal at multiple reception points and/or coordinated scheduling decisions among points to control interference and improve coverage.

SUMMARY

The Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

The methods and apparatus described herein, taken alone or in combination, enable a wireless transmit/receive unit (WTRU) to transmit different types of uplink channels or signals in a system deployment where multiple destination points may exist. In some embodiments described herein, the methods enable a WTRU to select the destination point of a transmission on a dynamic basis. In a system where destination point selection from among multiple potential destination points may be possible for a WTRU transmission, some embodiments of the system and methods provide for determination of the handling of hybrid automatic repeat request (HARQ) retransmissions and for new (e.g., contemplated by embodiments) power headroom reporting mechanisms. In further embodiments, methods are described to reduce or inhibit WTRU transmissions to destination points to which the WTRU has lost connectivity. Reference signals (RS) may be enhanced by using a pre cyclic shift (CS) offset to compensate the peak drift due to unpaired bandwidth (BW) allocation, introducing another layer of hopping over different sizes of RS' or using method to decouple CS hopping from selection of base sequences. Methods are also described to determine an initial value of CS hopping and other parameters based on reinterpretation of cyclic shift field (CSF). Different transmit power control (TPC) commands for aperiodic sounding reference signal (SRS), periodic SRS and physical uplink shared channel (PUSCH) are also described. Additional power control methods are described for SRS using decoupled TPC commands. Methods to enhance physical uplink shared channel (PUSCH) resource block (RB) mapping based on more dynamic PUSCH RB allocation are also disclosed. Additional methods for selection of uplink transmission contexts (UTC) for physical uplink control channel (PUCCH) are described. Methods are also described to handle TPC commands for multiple UTC's or for groups of physical channels and/or transmission types and on how to deal with subframe subsets where WTRU's may have limited transmission possibilities, such as for example, Further enhanced inter-cell interference coordination (FeICIC).

Embodiments contemplate a wireless transmit/receive unit (WTRU), that may comprise a processor. The processor may be configured, at least in part, to select at least one Uplink Transmission Context (UTC). The at least one UTC may correspond to one or more characteristics. The processor may be configured to select at least one of the one or more characteristics. The processor may also be configured to initiate a transmission based, at least in part, on the at least one of the one or more characteristics.

Embodiments contemplate a wireless transmit/receive unit (WTRU) that may comprise a processor. The processor may be configured, at least in part, to select at least one Uplink Transmission Context (UTC) that may correspond to a transmission type. The processor may be configured to determine a transmit power that may correspond to the at least one UTC. The processor may also be configured to initiate a transmission that may correspond to the transmission type at the determined power.

Embodiments contemplate a wireless transmit/receive unit (WTRU) that may comprise a processor, where the processor may be configured, at least in part, to determine an initial value for cyclic shift (CS) hopping. The processor may be configured to decouple the initial value for CS hopping from a fssPUSCH. The processor may also be configured to correlate the initial value for CS hopping to at least one Uplink Transmission Context (UTC).

