First of all, the discontinuous transmission (DTX) on UL and DL will impact the timing relations, such as UL scheduling and HARQ. This in turn may have an impact on performance such as latency.
The following major impacts are:
UL grant addressing multiple UL sub-frames. This is a need for asymmetric configurations with more UL sub-frames than DL sub-frames. Also, the timing relation between the PDCCH and the actually scheduled UL sub-frame may be different as compared to FDD.
DL transmission of multiple ACK/NAKs for several UL sub-frames. In asymmetric configurations with more UL sub-frames than DL sub-frames, ACK/NAKs in response to UL transmissions in several different UL sub-frames need to be transmitted in the same DL sub-frame.
UL transmission of multiple ACK/NAKs for several DL sub-frames. In the asymmetric configurations with more DL sub-frames than UL sub-frames, a UE may need to transmit ACK/NAKs associated with several different DL sub-frames in a single UL sub-frame. Since the multiplexing capacity on PUCCH goes down drastically with just a few UL sub-frames available, it is likely that there may be certain scheduling constraints for the DL in order to avoid excessive overhead in the UL.One possibility is to send only one ACK/NAK message in response to transmissions in several DL sub-frames.
Timing relation for ACK/NAK transmission. Since uplink and downlink are discontinuous, the timing relations will be different as compared to FDD. Also, the number of HARQ processes and the round trip time will depend on the asymmetry. Up to 15 processes are needed for extreme asymmetries.