Coordinated Uplink Delay Spread Compensation
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Solution Overview
Problem
In wireless communication networks, particularly under LTE, the precision of timing required for uplink transmissions is challenging due to variations in propagation delays, leading to excessive delay spread, which can result in improper decoding and interference, forcing base stations to either exclude participation in CoMP service or expand the tolerance window, both of which degrade service quality.
Innovation Solution
The method involves time-shifting the decoding start time for uplink data-units received from CoMP UEs at participating base stations to accommodate excessive delay spread, ensuring simultaneous decoding and reducing interference by adjusting uplink scheduling strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If base stations participate in CoMP service with strict timing alignment, then decoding precision is maintained, but base stations must exclude participation when delay spread exceeds tolerance
Solution Approach 1:
The patent applies dynamics by making the decoding start time flexible rather than fixed. Base stations dynamically adjust their decoding start times based on their specific propagation delays to each UE, allowing them to participate in CoMP service even when delay spread exceeds the traditional tolerance window, thus resolving the contradiction between maintaining decoding precision and enabling CoMP service participation.
2Adaptability or versatility
If base stations expand the tolerance window to accommodate delay spread, then CoMP service participation is enabled, but decoding precision and service quality degrade
Solution Approach 1:
The patent applies local quality by allowing each base station to have its own customized decoding start time based on its specific propagation delay characteristics to the UE. Instead of using a uniform expanded tolerance window that degrades precision for all base stations, each base station adjusts its decoding timing locally to match its specific delay conditions, enabling CoMP participation while maintaining decoding precision.
3Device complexity
If base stations use fixed decoding start times, then simultaneous decoding is simplified, but delay spread causes improper decoding and interference
Solution Approach 1:
The patent applies preliminary action by having base stations pre-determine and pre-coordinate their individual decoding start times based on known propagation delays before the actual uplink transmission occurs. This advance planning allows each base station to know exactly when to start decoding, maintaining simplicity while avoiding the improper decoding and interference caused by delay spread.
Data Source
AI summary
Disclosed is a method and system for compensating excessive delay spread in uplink coordinated multipoint service. An uplink data-unit transmitted by a user equipment device (UE) on a first uplink air interface to a first base station (BS) using a first group of sub-carrier frequencies may be received at a time that is within an alignment-time range for simultaneously decoding uplink data-units from UEs transmitting on the first uplink. A determination is made that the uplink data-unit transmitted simultaneously by the UE on a second uplink air interface using a second group of sub-carrier frequencies will be received at a second BS at a time that is time is beyond the alignment-time range for simultaneously decoding uplink data-units from UEs transmitting on the second uplink. Decoding of the received uplink data-unit at the second BS is then delayed until a start time beyond the end of the alignment-time range.