F-OFDM Subband Parameter Configuration for Air Interface Flexibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Orthogonal Frequency Division Multiplexing (OFDM) technologies face challenges with severe out-of-band leakage, strict synchronization requirements, and inflexibility in air interface design due to consistent subcarrier spacing, symbol length, and cyclic prefix length across the entire LTE system bandwidth, leading to high signaling overheads and limited flexibility in multi-user uplink transmissions.
Innovation Solution
Filtered Orthogonal Frequency Division Multiplexing (F-OFDM) divides system bandwidth into independent subbands with varying subcarrier spacings, symbol lengths, and cyclic prefix lengths, allowing for optimized parameter selection based on channel scenarios or service types, and clarifies the frequency location relationship between subbands to simplify signal processing and protocol design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If OFDM uses consistent subcarrier spacing, symbol length, and cyclic prefix length across the entire LTE system bandwidth, then system synchronization and signal processing are simplified, but the air interface design becomes inflexible and signaling overheads increase in multi-user uplink transmissions
Solution Approach 1:
The patent divides the system bandwidth into multiple independent subbands, where each subband can have different OFDM parameters (subcarrier spacing, symbol length, cyclic prefix length). This segmentation allows flexible parameter configuration for different service types and channel scenarios while maintaining manageable complexity through localized processing.
Solution Approach 2:
Different subbands are assigned different OFDM parameters according to local requirements - for example, subbands suitable for wideband services use larger subcarrier spacing, while subbands for narrowband services use smaller spacing. This local optimization improves overall system adaptability without requiring uniform parameter changes across the entire bandwidth.
2Reliability
If OFDM requires strict frequency synchronization and good time synchronization for all subcarriers, then transmission reliability is improved, but timing advance adjustment generates high signaling overheads
Solution Approach 1:
By segmenting the bandwidth into subbands with independent parameter configurations, the patent reduces the scope of synchronization requirements. Each subband can be synchronized independently, reducing the timing advance adjustment overhead compared to system-wide synchronization while maintaining reliable transmission within each subband.
3Reliability
If OFDM uses a subcarrier waveform that is a sinc function, then orthogonality between subcarriers is achieved, but out-of-band leakage becomes severe requiring guard bands
Solution Approach 1:
The patent applies different windowing functions or filtering techniques to different subbands based on their specific requirements. This local optimization reduces out-of-band leakage in subbands where it is critical while maintaining orthogonality, and allows for more efficient guard band utilization compared to uniform OFDM across the entire bandwidth.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention discloses a communication method and a communications apparatus, and belongs to the field of communications technologies. The method includes: determining, by a first communications device, a first subcarrier spacing corresponding to a first subband; and performing, by the first communications device, signal transmission on the first subband with a second communications device based on the first subcarrier spacing; or determining, by a first communications device, a second subcarrier spacing corresponding to a second subband; and performing, by the first communications device, signal transmission on the second subband with a second communications device based on the second subcarrier spacing. The first subcarrier spacing is different from the second subcarrier spacing, and both the first subcarrier spacing and the second subcarrier spacing are integral multiples of a basic frequency spacing; and both bandwidth of the first subband and bandwidth of the second subband are integral multiples of the basic frequency spacing.