GFDM Frame Structure for IEEE 802.11ay PAPR Reduction
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Solution Overview
Problem
High Peak-to-Average Power Ratio (PAPR) in 60 GHz WiGig/IEEE 802.11ad OFDM systems degrades power amplifier efficiency and causes spurious emissions, while Generalized Frequency Division Multiplexing (GFDM) with fewer subcarriers wastes frequency resources and introduces Inter Carrier Interference (ICI).
Innovation Solution
Implementing subcarrier upshifting and downshifting to reduce the DC null area, and a transmitter-side ICI reduction scheme to minimize computational complexity and power consumption, thereby improving PAPR performance and maintaining throughput similar to OFDM while reducing ICI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM is used in 60 GHz WiGig systems, then high throughput is achieved, but PAPR increases causing power amplifier inefficiency and spurious emissions
Solution Approach 1:
The patent changes the fundamental parameter of subcarrier arrangement by introducing GFDM with fewer, wider subcarriers instead of many narrow OFDM subcarriers. This parameter change reduces PAPR while maintaining throughput, directly resolving the contradiction between productivity and energy loss.
2Loss of energy
If GFDM with fewer subcarriers is used, then PAPR is reduced, but frequency resources are wasted and ICI is introduced
Solution Approach 1:
The patent applies local quality by making subcarriers non-uniform in width and positioning them strategically rather than uniformly across the spectrum. This allows efficient use of frequency resources while maintaining low PAPR characteristics of GFDM.
Solution Approach 2:
The patent introduces dynamic subcarrier allocation and flexible resource block structures that adapt to different transmission conditions, optimizing frequency resource utilization while maintaining the low PAPR advantage of GFDM.
3Loss of energy
If GFDM with fewer subcarriers is used, then PAPR is reduced, but ICI is introduced requiring complex mitigation
Solution Approach 1:
The patent applies preliminary action by implementing ICI reduction techniques at the transmitter side before signal transmission, rather than requiring complex receiver-side processing. This reduces the complexity burden on the receiver while maintaining low PAPR performance.
Solution Approach 2:
The patent introduces intermediary processing elements such as windowing functions and filtering mechanisms that mediate between the GFDM signal structure and the transmission channel, reducing ICI without requiring complex mitigation at the receiver.
4Adaptability or versatility
If traditional OFDM frame structure is used, then compatibility is maintained, but DC null area wastes frequency resources
Solution Approach 1:
The patent applies asymmetry by breaking the traditional symmetric OFDM frame structure and introducing asymmetric GFDM frame structures with flexible subcarrier arrangements. This allows reduced DC null area while maintaining compatibility through careful design of the asymmetric structure.
Data Source
AI summary
In 60 GHz WiGig/IEEE 802.11ad, Orthogonal Frequency Division Multiplexing (OFDM) is used to achieve higher throughput. However, OFDM has one problem of high Peak-to-Average Power Ratio (PAPR) caused by the summing up of the large number of subcarriers. A high PAPR signal degrades the efficiency of power amplifier (PA) and may cause spurious emissions because of the PA non linearity. In order to reduce PAPR, Generalized Frequency Division Multiplexing (GFDM) which has the characteristics of both single carrier and multi carrier transmission has been studied. By introducing GFDM, the number of subcarriers can be decreased while still maintaining a high throughput.