Wireless Signal Formation Using Dual-Domain Spreading Codes
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Solution Overview
Problem
In wireless communication systems, when multiple terminals share the same resources for transmitting control information like ACK/NAK signals, there is significant interference between terminals in the same cell and different cells, which existing code division multiplexing (CDM) techniques struggle to efficiently mitigate.
Innovation Solution
A method using two spreading codes, one in the frequency domain and one in the time domain, with specific sequence allocation rules to minimize interference, including cyclic shifts and Walsh sequences, to identify and separate terminals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If code division multiplexing (CDM) is used to allow multiple terminals to simultaneously transmit ACK/NAK signals using the same time and frequency resources, then resource utilization efficiency is improved, but interference between terminals in the same cell and different cells increases
Solution Approach 1:
The patent segments the spreading code into two independent components: a frequency domain spreading code and a time domain spreading code. Each terminal is assigned a unique combination of these two codes, allowing the system to separately control and optimize interference mitigation in both frequency and time dimensions while maintaining high resource utilization through CDM
Solution Approach 2:
The patent introduces an additional dimension for code differentiation by using both frequency domain and time domain spreading codes simultaneously. This two-dimensional code space provides greater separation between terminal signals, reducing interference while allowing more terminals to share the same time-frequency resources
2Device complexity
If a single spreading code is used in either frequency or time domain, then implementation complexity is reduced, but interference reduction effectiveness is insufficient
Solution Approach 1:
The patent merges frequency domain spreading and time domain spreading into a unified CDM framework. By combining these two spreading mechanisms, the system achieves enhanced interference reduction effectiveness without significantly increasing implementation complexity, as both spreading operations can be integrated into the existing signal processing chain
Data Source
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AI summary
Provided is method of forming a signal in a wireless communication system in which a plurality of terminals commonly use a resource in the time domain and the frequency domain. The method includes multiplying a signal to be transmitted by a frequency domain orthogonal code symbol corresponding to a first cyclic shift index in a first slot to be transmitted to a base station, wherein the multiplying is performed by a first terminal and a second terminal; and multiplying information to be transmitted by a frequency domain orthogonal code symbol corresponding to a second cyclic index that is different from the first cyclic index of the first slot to be transmitted to the base station, in a second slot, wherein the multiplying is performed by the first terminal and the second terminal.