OFDMA Downlink Acknowledgment Multiplexing for Power Reduction
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Solution Overview
Problem
Current downlink resource allocation and acknowledgment mechanisms in OFDMA communication systems are inefficient, particularly for VoIP traffic, as they consume excessive power and bandwidth to handle a large number of users, leading to inaccurate detection and decoding at the cell edge.
Innovation Solution
The system employs a method to distribute downlink acknowledgments across multiple OFDMA frequency sub-carriers using orthogonal sequences, allowing for efficient power allocation and minimizing interference, while users determine their acknowledgment channels based on uplink resource unit assignments, enabling accurate detection and decoding without excessive power or bandwidth consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downlink resource allocation and acknowledgment mechanisms allocate a resource block per user, then accurate detection and decoding is guaranteed, but power and bandwidth consumption becomes excessive
Solution Approach 1:
The patent combines multiple users' acknowledgment signals into a single shared resource block using code division multiplexing. Each user's acknowledgment is spread with a unique orthogonal code, allowing the base station to detect multiple acknowledgments simultaneously in one resource block, thereby reducing power and bandwidth consumption while maintaining detection accuracy through code-based separation
Solution Approach 2:
The patent creates a universal acknowledgment resource block that serves multiple users simultaneously. Instead of dedicating separate resource blocks to each user, a single resource block is designed to carry acknowledgments for multiple users through code division, making the resource block multi-functional and reducing overall system power and bandwidth usage
2Measurement precision
If downlink resource allocation and acknowledgment mechanisms allocate a resource block per user, then accurate detection and decoding is guaranteed, but bandwidth consumption becomes excessive
Solution Approach 1:
The patent merges multiple users' acknowledgment transmissions into a single shared resource block using code division multiplexing. Each user is assigned a unique orthogonal code to spread their acknowledgment signal, enabling the base station to decode multiple acknowledgments from one resource block, thereby reducing bandwidth consumption while preserving decoding accuracy through orthogonal code separation
Solution Approach 2:
The patent transitions from time-frequency resource allocation to code domain multiplexing. Instead of allocating separate time-frequency resource blocks to each user, the system uses the code dimension to separate user signals within a single resource block, effectively adding a new dimension for user separation that reduces overall bandwidth requirements
3Productivity
If the number of users served is increased due to smaller voice packet sizes, then system capacity is improved, but control and feedback mechanisms consume more power and bandwidth
Solution Approach 1:
The patent combines control and feedback signals for multiple users into shared resource blocks using code division multiplexing. As system capacity increases with more VoIP users, the control mechanism uses orthogonal codes to multiplex acknowledgments and transmit indicators for all users within limited resource blocks, preventing power and bandwidth consumption from increasing linearly with user count
Solution Approach 2:
The patent changes the parameter of resource allocation from per-user dedicated blocks to shared blocks with code division. This parameter change allows the control mechanism to handle increased user capacity efficiently, as the power and bandwidth consumption grows sub-linearly with the number of users supported
4Productivity
If the number of users served is increased due to smaller voice packet sizes, then system capacity is improved, but bandwidth consumption increases
Solution Approach 1:
The patent merges feedback signals for multiple users into shared resource blocks using code division multiplexing. As the number of VoIP users increases, the system uses orthogonal codes to pack multiple user acknowledgments and transmit indicators into fewer resource blocks, reducing bandwidth consumption per user and overall bandwidth efficiency
Data Source
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AI summary
A communication system (100) provides downlink acknowledgments corresponding to uplink transmission using hybrid automatic repeat request to multiple users (101, 102) in an Orthogonal Frequency Division Multiplexing communication system, wherein a frequency bandwidth comprises multiple frequency sub-carriers, by spreading (804) each acknowledgment of multiple acknowledgments with a selected spreading sequence of multiple spreading sequences to produce multiple spread acknowledgments, wherein each acknowledgment is intended for a different user of the multiple users, and distributing (810) the multiple spread acknowledgments across the multiple frequency sub-carriers.