Uplink Timing Estimation via Downlink Frame Offset Tracking

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In wireless communication systems, especially in Mobile Wimax, the existing methods for predicting UpLink (UL) transmission timing based on DownLink (DL) timing fail to accurately synchronize when the Mobile Station (MS) moves, leading to changes in propagation delay and channel state, resulting in incorrect UL transmission timing and deteriorated link throughput.

Innovation Solution

An apparatus and method that estimate the time offset between DownLink (DL) reception frames to dynamically regulate UpLink (UL) transmission timing in a Mobile Station (MS), using a DL time tracker, time offset calculator, and UL time estimator to adjust UL transmission timing for each frame based on changes in channel state and propagation delay.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UL transmission timing is predicted based on DL timing using a fixed time interval, then the system operates correctly in fixed location environments, but the UL transmission timing becomes incorrect when the MS moves and propagation delay changes

Engineering Contradiction:

ImproveUL transmission timing accuracyVSAvoidadaptability to propagation delay changes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic UL timing prediction by continuously tracking DL frame reception timing and calculating time offsets between consecutive DL frames. Instead of using a fixed time interval, the system adapts the UL transmission timing based on the actual measured time differences in each frame, allowing it to respond to propagation delay changes caused by MS movement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from DL frame reception timing to adjust UL transmission timing. By measuring the actual reception time of each DL frame and calculating the time offset from the previous frame, the system creates a closed-loop mechanism that continuously corrects UL timing predictions based on observed DL timing variations.

Inventive Principle:

Principle #23Feedback

2Reliability

If ranging response messages are used to regulate UL timing, then timing correction is achieved, but the response time is delayed until the ranging response is received

Engineering Contradiction:

Improvetiming synchronization accuracyVSAvoidtime delay before timing correction

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary timing predictions for each DL frame by calculating the time offset from the previous DL frame reception. This allows the MS to proactively adjust UL transmission timing before sending ranging requests, reducing the time delay associated with waiting for ranging response messages from the BS.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system prepares timing corrections in advance by continuously tracking DL frame timing and maintaining a record of time offsets. This cushioning mechanism ensures that when timing adjustments are needed, the MS already has preliminary correction values ready, reducing the overall time penalty.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If the MS uses a previously predicted time interval for UL transmission, then transmission can proceed without waiting for ranging responses, but the UL frame reception timing at the BS becomes incorrect when propagation delay changes

Engineering Contradiction:

ImproveUL transmission continuityVSAvoidUL reception timing accuracy at BS

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent maintains continuous UL transmission by calculating time offsets for every DL frame received. This continuous update mechanism ensures that the MS always has the latest timing prediction available, allowing uninterrupted UL transmissions while progressively improving timing accuracy as more DL frames are processed.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system periodically updates UL timing predictions based on each received DL frame. By using the periodic arrival of DL frames as trigger points for timing recalculation, the system maintains regular timing updates without requiring continuous intervention, balancing transmission continuity with timing precision.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS8565213B2Apparatus and method for estimating uplink transmission timing in wireless communication system

Publication Date: 2013.10.22 SAMSUNG ELECTRONICS CO LTD

AI summary

An apparatus and method for estimating UpLink (UL) transmission timing in a Mobile Station (MS) of a wireless communication system are provided. The method includes tracking DL timing by using a DL preamble signal received for each frame; estimating a time offset between a previous frame and a current frame by using the DL timing tracked for each frame; and estimating the UL transmission timing by using the estimated time offset.