1-bit Control Signal Multiplexing via CDMA Orthogonal Codes
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Solution Overview
Problem
In multi-carrier mobile communication systems, the efficient transmission of 1-bit control signals, such as ACK/NACK signals, is hindered by significant power differences among signals, leading to inter-cell interference and reliability issues, particularly when using TDMA and FDMA, which affect downlink data packet scheduling and channel transmission reliability.
Innovation Solution
The method involves multiplexing 1-bit control signals using Code Division Multiple Access (CDMA) within a prescribed time-frequency domain and repeating these signals across different frequency domains, employing orthogonal or pseudo-orthogonal codes to differentiate and modulate the signals, allowing for efficient transmission and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If TDMA and FDMA are used to multiplex control signals, then time-frequency resource allocation is simplified, but power differences among signals cause inter-cell interference and reliability issues
Solution Approach 1:
The patent combines TDMA, FDMA, and CDMA into a unified multiplexing framework. Control signals are first multiplexed using TDMA in the time domain, then FDMA in the frequency domain, and finally CDMA with orthogonal codes to address power differences. This layered combination resolves the reliability issues caused by power variations while maintaining resource allocation efficiency.
Solution Approach 2:
The patent employs a composite multiplexing approach using multiple access techniques together. By layering TDMA, FDMA, and CDMA, the system creates a robust control signal transmission mechanism that leverages the strengths of each technique while compensating for their individual weaknesses, particularly in handling power differences among control signals.
2Productivity
If multiple 1-bit control signals are transmitted simultaneously using TDMA/FDMA, then resource utilization improves, but power differences create inter-cell interference
Solution Approach 1:
The patent converts the harmful effect of power differences into a beneficial feature by using orthogonal codes in CDMA. Each control signal is assigned a unique orthogonal code that allows the receiver to distinguish and separately process signals with different power levels. The previously harmful power variations become useful for maintaining signal distinguishability and reducing inter-cell interference.
Solution Approach 2:
The patent introduces orthogonal codes as an intermediary mechanism between the control signals and the transmission medium. These codes act as mediators that enable signals with different power levels to coexist without causing excessive interference, allowing efficient simultaneous transmission while maintaining signal integrity.
3Speed
If control signals are multiplexed without considering power differences, then transmission speed increases, but reception reliability decreases
Solution Approach 1:
The patent applies local quality by assigning different orthogonal codes to control signals based on their specific power characteristics and transmission requirements. Each signal receives a tailored code that optimizes its reception reliability given its local power conditions, allowing fast simultaneous transmission while maintaining individual signal integrity through localized code assignment.
Data Source
AI summary
A method of transmitting a control signal using efficient multiplexing is disclosed. The present invention includes the steps of multiplexing a plurality of 1-bit control signals within a prescribed time-frequency domain by code division multiple access (CDMA) and transmitting the multiplexed control signals, wherein a plurality of the 1-hit control signals include a plurality of the 1-bit control signals for a specific transmitting side. Accordingly, reliability on 1-bit control signal transmission can be enhanced.