Relay Station Multicast Signal Timing Synchronization

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Solution Overview

Problem

In LTE-Advanced networks with relay stations, there is an unavoidable delay in transmitting MBSFN signals, which can cause deterioration of reception characteristics due to increased multipath delay, as relay stations may not transmit according to the predetermined schedule.

Innovation Solution

The system synchronizes the transmission timing of radio signals between base stations and relay stations, allowing relay stations to either decode unicast information or omit decoding multicast information, and transmit signals accordingly to prevent delays in MBSFN signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If relay stations decode and re-encode data transmitted from base stations, then the relay station can perform Layer 2 relay operation, but transmission delay increases and MBSFN signal timing synchronization deteriorates

Engineering Contradiction:

Improverelay operation capabilityVSAvoidtransmission delay

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent segments the relay operation into two distinct modes: Layer 2 relay for unicast data (with decoding/re-encoding) and Layer 1 relay for multicast data (without decoding). This segmentation allows each mode to be optimized independently - Layer 2 relay provides adaptability and error correction, while Layer 1 relay maintains timing synchronization for MBSFN signals.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The relay station dynamically switches between different relay modes based on the data type. For unicast data, it operates in Layer 2 mode with full decoding and re-encoding. For multicast data, it operates in Layer 1 mode with simple amplification and forwarding, thereby adapting the processing depth to the specific requirements of each data stream.

Inventive Principle:

Principle #15Dynamics

2Reliability

If relay stations perform decoding and re-encoding for all data, then data reliability improves, but transmission timing for multicast signals deteriorates

Engineering Contradiction:

Improvedata reliabilityVSAvoidsignal timing precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies different processing qualities to different data types. Unicast data receives full decoding and re-encoding processing for high reliability, while multicast data receives minimal processing to preserve timing precision. This local quality differentiation ensures that each data type gets the appropriate level of processing without compromising the other.

Inventive Principle:

Principle #3Local quality

3Reliability

If relay stations transmit MBSFN signals after decoding, then error correction improves, but multipath delay increases and reception characteristics deteriorate

Engineering Contradiction:

Improveerror correction capabilityVSAvoidmultipath delay

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the error correction function from the MBSFN signal transmission path. Instead of decoding MBSFN signals at the relay station (which would add multipath delay), the error correction is handled at the base station before transmission. The relay station simply amplifies and forwards the already-protected signal, eliminating the harmful multipath delay effect.

Inventive Principle:

Principle #2Taking out (Extraction)

4Adaptability or versatility

If relay stations use Layer 3 relay operation with own cell ID, then network flexibility improves, but complexity of scheduling and coordination increases

Engineering Contradiction:

Improvenetwork flexibilityVSAvoidscheduling complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The relay station is designed with multi-functionality, capable of operating in both Layer 2 mode (with DeNB scheduling) and Layer 1 mode (with simplified forwarding). For MBSFN signals, it operates in Layer 1 mode with minimal processing, while maintaining the capability to perform Layer 3 operations when needed, thereby reducing overall system complexity while preserving flexibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8811257B2Mobile communication system, relay station apparatus, base station apparatus, radio relay method, and computer readable medium

Publication Date: 2014.08.19 NEC CORP

AI summary

In one embodiment, a relay station (11) receives a first radio signal into which transfer information to be transmitted to a mobile station (12) is encoded from a donor base station (10) through a backhaul link. When the transfer information encoded into the first radio signal is unicast information addressed to the mobile station (12), the relay station (11) decodes the unicast information and generates a third radio signal into which the unicast information is re-encoded. Further, the relay station (11) is configured such that when the transfer information encoded into the first radio signal is multicast information, the relay station (11) is able to omit decoding the multicast information. In this way, multicast information that is delayed from the predefined transmission timing is prevented from being transmitted from the relay station (11).