Dynamic Frequency Allocation for SC-FDM Control Information
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in transmitting data and control information, particularly in multiple-access systems like CDMA, TDMA, FDMA, OFDMA, and SC-FDMA, where peak-to-average ratio (PAR) of single-carrier frequency division multiplexing (SC-FDM) waveforms is high, affecting power amplifier operation and throughput.
Innovation Solution
Control information is sent in a first frequency location when no data is being sent and in a second frequency location when data is being sent, using contiguous subcarriers for both, which improves the PAR of the SC-FDM waveform by allowing dynamic transmission of control information based on data availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control information is always sent in a dedicated control region, then control information transmission is reliable, but system throughput decreases due to wasted resources when no data is being sent
Solution Approach 1:
The patent implements dynamic frequency allocation where the UE transmits control information in a first frequency location (dedicated control region) when no data is being sent, and switches to a second frequency location (data region) when data is being sent. This dynamic switching optimizes resource utilization while maintaining reliable control information transmission in both scenarios.
2Productivity
If control information and data are multiplexed in the same resource blocks, then resource utilization improves, but the peak-to-average ratio of SC-FDM waveform increases affecting power amplifier efficiency
Solution Approach 1:
The patent segments the frequency spectrum into different locations: a first frequency location for control information and a second frequency location for data. By separating control and data transmissions in frequency domain while using contiguous subcarriers within each location, the SC-FDM waveform maintains low peak-to-average ratio, improving power amplifier efficiency while still achieving efficient resource utilization.
3Reliability
If non-contiguous subcarriers are used for control information transmission, then frequency diversity is achieved, but the peak-to-average ratio of the waveform increases
Solution Approach 1:
The patent applies local quality by assigning contiguous subcarriers within the first frequency location for control information transmission. This localized contiguous allocation maintains low peak-to-average ratio for SC-FDM waveform, while the dedicated first frequency location provides frequency diversity separation from data transmissions in the second frequency location.
Data Source
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AI summary
Techniques for sending control information in a communication system are described. In an aspect, control information may be sent in a first frequency location (e.g., a first set of subcarriers) if data is not being sent and in a second frequency location (e.g., a second set of subcarriers) if data is being sent. In another aspect, control information may be processed in accordance with a first processing scheme if data is not being sent and with a second processing scheme if data is being sent. In one design of the first scheme, a CAZAC sequence may be modulated with each modulation symbol for control information to obtain a corresponding modulated CAZAC sequence, which may be sent on the first set of subcarriers. In one design of the second scheme, modulation symbols for control information may be combined with modulation symbols for data, transformed to frequency domain, and mapped to the second set of subcarriers.