Multipoint Uplink Transmission for HARQ and Power Control
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Solution Overview
Problem
Existing wireless communication systems face challenges in managing coordinated multipoint transmissions (CoMP) for LTE wireless systems, particularly in handling hybrid automatic repeat request (HARQ) retransmissions and power headroom reporting mechanisms, especially when multiple destination points are involved, and dealing with connectivity loss and interference.
Innovation Solution
The system enables a wireless transmit/receive unit (WTRU) to dynamically select a destination point for transmissions, incorporates enhanced reference signals using pre-cyclic shift offsets, decouples cyclic shift hopping from base sequences, and implements dynamic power control methods for different types of uplink channels to manage HARQ retransmissions and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coordinated multipoint transmission (CoMP) is implemented with multiple destination points, then network coverage and reliability are improved, but system complexity and difficulty of managing HARQ retransmissions increase
Solution Approach 1:
The patent segments the CoMP system into multiple transmission points (TPs) with distinct roles (serving TP, coordinating TPs) and separates HARQ management into point-specific HARQ processes. Each TP maintains independent HARQ state information, allowing complex multipoint coordination to be broken down into manageable individual point operations while maintaining overall system reliability.
Solution Approach 2:
The patent introduces a serving transmission point as an intermediary that coordinates between the wireless device and multiple coordinating TPs. The serving TP manages HARQ retransmissions and coordinates with other TPs, simplifying the overall system complexity by providing a central management point while still enabling complex multipoint transmissions.
2Productivity
If dynamic destination point selection is enabled, then transmission efficiency is improved, but power control complexity and interference management difficulty increase
Solution Approach 1:
The patent implements dynamic destination point selection where the serving TP can change based on channel conditions, device location, and traffic patterns. This dynamic adaptation allows the system to optimize transmission efficiency by selecting the most appropriate serving TP while maintaining manageable power control through dynamic TPC commands adjusted according to the current serving point.
Solution Approach 2:
The patent changes key parameters dynamically including the serving TP identification, power control offsets, and HARQ process allocation based on channel conditions and traffic requirements. By adjusting these parameters dynamically, the system achieves high transmission efficiency while keeping power control complexity manageable through standardized parameter adjustment mechanisms.
3Productivity
If multiple uplink channels are transmitted to different destination points, then resource utilization is improved, but interference coordination difficulty and power headroom reporting complexity increase
Solution Approach 1:
The patent creates a universal power control framework that works across multiple uplink channels (PUSCH, PUCCH, SRS) and multiple destination points. The same power control mechanisms, TPC commands, and pathloss reference signal structures are used universally for all channels and points, simplifying interference coordination and power headroom reporting despite the complexity of multi-channel transmissions.
Solution Approach 2:
The patent performs preliminary configuration of power control parameters, pathloss reference signals, and HARQ process allocations before actual transmissions occur. This preliminary setup allows the system to efficiently manage multiple uplink channels to different destination points without real-time complexity, as the coordination framework is established in advance.
Data Source
AI summary
Embodiments contemplate wireless transmit/receive unit (WTRU) transmissions of different types of uplink channels and/or signals in a system deployment where multiple destination points may exist. Some embodiments contemplate that a WTRU may select the destination point of a transmission on a dynamic basis. In one or more systems where destination point selection from among multiple potential destination points may be possible for a WTRU transmission, some embodiments contemplate the determination of the handling of hybrid automatic repeat request (HARQ) retransmissions and for different power headroom reporting mechanisms. Embodiments also contemplate the reduction and/or inhibition of WTRU transmissions to destination points to which the WTRU may have lost connectivity.