OFDM Subframe Bit Layout Without Guard Periods

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Solution Overview

Problem

Existing methods for mitigating inter-/intra-UE interference in OFDM-based D2D communication networks are inefficient, leading to resource wastage and interference issues, particularly due to the need for guard periods that occupy significant bandwidth.

Innovation Solution

Incorporating only redundancy bits into the head and tail OFDM symbols of radio subframes, allowing systematic bits to be unaffected by interference and eliminating the need for guard periods, thereby improving resource efficiency and ensuring successful demodulation and decoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If guard periods are inserted to mitigate interference in OFDM symbols, then interference protection is improved, but bandwidth utilization deteriorates due to resource wastage

Engineering Contradiction:

Improveinterference protectionVSAvoidbandwidth utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts only the necessary redundancy bits and places them specifically in the head and tail OFDM symbols, separating them from systematic bits. This allows the head/tail symbols to serve as interference sacrificial zones without requiring additional guard periods, thus protecting systematic bits while maintaining bandwidth utilization

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful interference affecting head/tail OFDM symbols into a beneficial structure by deliberately placing redundancy bits in these positions. The interference that would normally corrupt data is now used to protect systematic bits, as the corrupted redundancy bits can be discarded while systematic bits remain intact

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If redundancy bits are placed in head and tail OFDM symbols, then systematic bits are protected from interference, but complexity of bit arrangement increases

Engineering Contradiction:

Improvesystematic bit protectionVSAvoidbit arrangement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the coded bits into systematic bits and redundancy bits, and further segments the OFDM symbols into head, middle, and tail portions. Systematic bits are placed in middle symbols while redundancy bits occupy head and tail symbols, creating a structured arrangement that simplifies interference management despite the initial segmentation complexity

Inventive Principle:

Principle #1Segmentation

3Reliability

If guard periods are used to prevent interference, then demodulation reliability is improved, but resource efficiency deteriorates

Engineering Contradiction:

Improvedemodulation reliabilityVSAvoidresource efficiency

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

Instead of using guard periods to prevent interference from affecting data, the patent inverts the approach by deliberately allowing interference to affect redundancy bits in head/tail symbols while protecting systematic bits. This inversion eliminates the need for guard periods and improves resource efficiency while maintaining demodulation reliability

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3000199B1Transmission and reception methods and associated communication devices for use in OFDM-based communication network

Publication Date: 2019.09.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

The present disclosure provides a terminal device and a method performed in the terminal device for communicating with a radio base station (RBS) or a Device-to-Device (D2D) terminal device. The method comprises forming a radio subframe by including coded bits in the radio subframe. The coded bits contain a sequence of systematic bits and a sequence of redundancy bits，and only redundancy bits are included in a head and a tail of the first and/or the last Orthogonal Frequency Division Multiplexing (OFDM) symbols of the radio subframe. The method further comprises transmitting the radio subframe to the radio base station RBS or the Device-to-Device (D2D) terminal device. The present disclosure also provides a communication device communicating with the proposed terminal device and a method performed in the communication device.