A novel time-domain synchronous block transmission frame structure for broadcasting return channel

In time-domain synchronous (TDS) block transmission systems, known symbols are padded in the guard interval between data blocks using some specific patterns. The complexity of channel estimation is relatively high for the time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) system. As a result, original TDSOFDM is only used for downlink broadcasting. This paper proposes a new frame structure based on TDS block transmission. The proposed frame structure can simplify the channel estimation and support the multiuser scenarios, due to the proposed padding sequence and its specific time and frequency allocation pattern. It supports the variable number of frames in one superframe, which provides the flexibility to combat various channel conditions and maintains the system efficiency. Because of these characters, it can be used in wireless uplink channel as an alternative orthogonal frequency division multiple access (OFDMA) structure. Simulation results show that the performance of the proposed frame structure is almost the same as the conventional OFDMA scheme, but has better spectrum efficiency. Therefore, it is preferred to be used in the return channel of terrestrial broadcasting systems