Hierarchical Multicast Coding for Mixed User Channel Conditions
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Solution Overview
Problem
Existing multiple-access communication systems face inefficiencies in transmitting signaling messages due to the need to accommodate users with the worst channel conditions, leading to suboptimal resource allocation and coding efficiency.
Innovation Solution
Hierarchical coding techniques are employed, where individual messages for users are encoded using multiple interconnected encoders, allowing each user to receive messages at a suitable data rate, and a single multicast message is generated for all users, using various coding architectures such as parallel, serial, or mixed architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a broadcast signaling channel is used to send messages to all users, then coding efficiency is improved, but resource utilization becomes inefficient because all users must be accommodated at the worst channel conditions
Solution Approach 1:
The patent segments the broadcast signaling channel into multiple hierarchical layers, where messages are encoded at different code rates corresponding to different channel conditions. Users with better channels receive higher code rate messages, while users with worse channels receive lower code rate messages. This segmentation allows the system to achieve high coding efficiency by grouping messages while avoiding resource waste by adapting to individual user channel conditions.
Solution Approach 2:
The patent applies local quality by assigning different code rates to different portions of the coded message based on user-specific channel conditions. Each user receives the same multicast message but with locally adapted coding parameters - users with good channels get higher code rates (more efficient resource use), while users with poor channels get lower code rates (ensuring reliable reception). This resolves the contradiction by making resource allocation locally optimized rather than uniformly conservative.
2Adaptability or versatility
If individual messages for each user are encoded separately on a unicast signaling channel, then each user receives messages at their suitable data rate, but coding efficiency deteriorates
Solution Approach 1:
The patent merges multiple individual user messages into a single hierarchical coded message structure. Instead of encoding separate unicast messages for each user, the system combines all user messages into one multicast transmission with hierarchical coding layers. This merging achieves high coding efficiency by exploiting redundancy across users while maintaining adaptability through the hierarchical structure that allows each user to decode at their appropriate data rate.
Solution Approach 2:
The hierarchical coded message structure serves multiple functions simultaneously - it acts as a universal multicast message for all users while also providing user-specific adapted data rates. The same transmitted signal serves as the broadcast channel for efficient coding and simultaneously as adapted unicast channels for each user based on their channel conditions, eliminating the need for separate encoding operations.
3Reliability
If a low code rate is used for the broadcast signaling channel to accommodate the worst user, then reliability is improved for all users, but resource allocation becomes inefficient
Solution Approach 1:
The patent introduces dynamics by making the code rate adaptive rather than static. Instead of using a fixed low code rate for all users, the system dynamically assigns different code rates to different users based on their channel conditions. The hierarchical structure allows code rates to be adjusted according to each user's reception capability, ensuring reliable decoding for worst-case users while allocating more efficient higher code rates to better users, thus improving overall resource allocation efficiency.
Data Source
AI summary
Techniques for sending signaling information using hierarchical coding are described. With hierarchical coding, individual messages for users are encoded using multiple interconnected encoders such that (1) the message for each user is sent at a data rate suitable for that user and (2) a single multicast message is generated for the messages for all users. A base station determines data rates supported by the users and the code rates to achieve these data rates. Each data rate is determined by one or more code rates. Signaling information for the users is mapped to data blocks to be sent at different data rates. Each data block is then encoded in accordance with the code rate(s) associated with the data rate for that data block. A final coded block is generated for all users and transmitted. Each user performs the complementary decoding to recover the message sent to that user.