Hybrid Time Interleaving with Twisted Block and Delay Line

The interleaving process is divided into two independent stages: intra-subframe interleaving (within each subframe) and inter-subframe interleaving (across subframes). The intra-subframe stage uses a block interleaver that operates independently on each subframe, while the inter-subframe stage uses a convolutional interleaver that operates on the sequence of subframes. This segmentation allows each stage to be decoded independently, significantly reducing overall decoding complexity while maintaining time diversity benefits.

A buffer memory is introduced as an intermediary component between the intra-subframe interleaver and the inter-subframe interleaver. This buffer stores the interleaved data from multiple subframes and provides it to the convolutional interleaver in the correct sequence. The buffer acts as a mediator that decouples the two interleaving stages, allowing them to operate independently with reduced complexity while achieving the desired time diversity through the combined effect of both stages.

The system dynamically selects between different interleaving modes (intra-subframe only, inter-subframe only, or hybrid) based on channel conditions and service requirements. The convolutional interleaver is configured with variable parameters including different delay line lengths and interleaving depths that can be adjusted according to the selected mode. This dynamic adaptability allows the system to optimize for efficiency when using hybrid mode while managing decoding complexity through parameter adjustment rather than structural complexity.

The patent employs parameter changes to control the behavior of the convolutional interleaver in hybrid-time mode. By adjusting the delay line length, interleaving depth, and buffer size parameters, the system can achieve efficient hybrid interleaving with controlled complexity. The parameters are optimized to balance the benefits of time diversity against the computational burden of decoding, allowing efficient operation without proportionally increasing complexity.

Virtual cells are generated as virtual copies or representations of actual data cells in the convolutional delay line. Instead of physically implementing separate storage locations for each virtual cell, the system creates logical representations that can be manipulated through software or control logic. This copying approach provides the flexibility of having multiple virtual cells with different characteristics while avoiding the hardware complexity of implementing each virtual cell as a separate physical entity.

A single physical buffer memory structure serves multiple functions by implementing both intra-subframe and inter-subframe interleaving operations. The same buffer is used to store data for the block interleaver and to provide data to the convolutional interleaver, eliminating the need for separate dedicated memory structures for each function. This multi-functionality reduces device complexity while maintaining the flexibility needed for hybrid-time interleaving operations.