Dynamic Tone Allocation for PAPR Reduction in OFDMA Systems

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Solution Overview

Problem

Conventional tone reservation methods for reducing peak-to-average power ratio (PAPR) in OFDMA modulation are limited by unused reserved tones and a fixed number of available tones, leading to inefficiencies in power amplification and uplink link budget, prompting a need for improved PAPR reduction techniques.

Innovation Solution

The System-Aided PAPR (SAPR) method dynamically reallocates sub-carriers from subscriber stations with strong uplink signals to those with weak signals, using a novel algorithm that embeds received signal strength information in resource allocation, allowing for flexible and efficient PAPR reduction without fixed reserved tones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional tone reservation is used to reduce PAPR, then PAPR reduction is achieved, but system overhead increases due to unused reserved tones

Engineering Contradiction:

ImprovePAPRVSAvoidsystem overhead

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent implements dynamic tone allocation where tones are not permanently reserved but dynamically assigned based on real-time PAPR reduction needs. The base station identifies which user equipment needs PAPR reduction and allocates specific tones to those users only when needed, making the tone reservation flexible and adaptive rather than static and fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of tone availability from fixed to variable. Instead of a predetermined set of reserved tones, the system dynamically determines which tones to use for PAPR reduction based on channel conditions, user requirements, and system load, thereby optimizing the use of available spectral resources.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If conventional tone reservation is used to reduce PAPR, then PAPR reduction is achieved, but the number of available reserved tones is limited and fixed

Engineering Contradiction:

ImprovePAPRVSAvoidflexibility of tone allocation

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent makes the tone allocation system universal by allowing any subcarrier to potentially serve as a reserved tone depending on system needs. Instead of designating specific frequency positions as permanently reserved, any tone in the OFDMA spectrum can be allocated for PAPR reduction purposes, maximizing the versatility and adaptability of the tone reservation mechanism.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If more reserved tones are allocated for PAPR reduction, then PAPR reduction effectiveness improves, but data transmission capacity decreases

Engineering Contradiction:

ImprovePAPR reduction effectivenessVSAvoiddata transmission capacity

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent applies partial action by allocating only the necessary number of tones for PAPR reduction rather than reserving a large fixed number. The system dynamically determines the optimal number of tones to allocate based on actual PAPR reduction needs, allocating more tones only when PAPR reduction effectiveness requires it, and fewer tones when data transmission capacity is prioritized.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system dynamically adjusts the number of reserved tones based on real-time system conditions. When PAPR reduction is critical (e.g., for users with poor channel conditions), more tones are allocated. When channel conditions are good or system load is low, fewer tones are reserved, allowing more resources for data transmission. This dynamic adjustment optimizes the trade-off between PAPR reduction effectiveness and data transmission capacity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8169959B2System aided PAPR reduction scheme based on TR algorithm

Publication Date: 2012.05.01 APPLE INC

AI summary

A peak-to-average power ratio (PAPR) reduction method, known as system-aided PAPR reduction (SAPR), is disclosed. Based on a TR algorithm, the SAPR method avoids the drawbacks of conventional tone reservation implementations, and reduces PAPR significantly, in some embodiments. The SAPR method may be applied to next generation OFDMA-based wireless broadband technologies, to increase system throughput and cell coverage.