Preamble Configuration for Interference-Free Spectrum Access
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Solution Overview
Problem
In wireless communications, maintaining synchronization among network entities in unlicensed spectrum during joint transmissions is challenging, leading to potential interference issues when one node accesses the spectrum after a resynchronization boundary while others are already transmitting.
Innovation Solution
Configuring preamble transmissions to avoid interference by allowing a second node to access the unlicensed spectrum currently used by a first node, with the second node transmitting a second burst of data having a preamble that does not interfere with the joint transmission portion of the first burst, using mechanisms such as listen-before talk (LBT) and clear channel assessment (CCA).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a second node accesses the unlicensed spectrum after a resynchronization boundary while a first node is transmitting, then spectrum utilization is improved, but interference occurs with the joint transmission portion of the first burst
Solution Approach 1:
The transmission burst is segmented into a preamble portion and a joint transmission portion. The second node transmits only its preamble after the resynchronization boundary while the first node continues its joint transmission portion, separating the transmission phases to allow both nodes to utilize the spectrum without mutual interference.
Solution Approach 2:
The second node performs preliminary action by transmitting its preamble before the joint transmission portion begins. This preliminary transmission establishes the second node's presence and allows the system to transition to joint transmission mode without interference, improving overall spectrum utilization.
2Object-affected harmful factors
If network entities maintain strict synchronization boundaries, then interference is reduced, but spectrum access efficiency deteriorates when nodes need to transmit data
Solution Approach 1:
The system dynamically adjusts transmission modes based on timing relative to resynchronization boundaries. Nodes transition from strict synchronization during joint transmission portions to more flexible asynchronous access during preamble portions, allowing the system to adapt between interference reduction and spectrum access efficiency based on operational context.
Solution Approach 2:
The transmission structure alternates between periodic synchronization boundaries and flexible access periods. At resynchronization boundaries, nodes align for joint transmission to minimize interference, while between these boundaries, nodes can access the spectrum more flexibly, creating a periodic pattern that balances both requirements.
3Productivity
If all network entities transmit simultaneously in unlicensed spectrum, then communication capacity is improved, but synchronization maintenance becomes more difficult
Solution Approach 1:
Simultaneous transmission is segmented into coordinated phases: preamble transmission phase where nodes can access independently, and joint transmission phase where nodes synchronize. This segmentation allows multiple nodes to transmit simultaneously overall while maintaining synchronization during critical data portions, balancing capacity with synchronization complexity.
Data Source
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AI summary
A method and apparatus for adjusting preamble transmissions to maintain synchronization with other network entities operating in an unlicensed spectrum during wireless communications are described. The method and apparatus include accessing, by a second node, a contention-based medium currently accessed by a first node transmitting a first burst of data. The method and apparatus further include transmitting, by the second node, a second burst of data over the accessed medium, the second burst of data having an associated preamble configured not to interfere with a joint transmission portion of the first burst of data. The first and second nodes may be enhanced-multimedia broadcast multicast service (eMBMS) nodes. Moreover, the joint transmission portion of the first burst of data may include transmission of one or more multicast-broadcast single-frequency network (MBSFN) subframes.