Contention-Based Access Power Control and Frequency Offset for Collision Avoidance
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Solution Overview
Problem
In the current mobile communication system, Node B cannot correctly determine the cause of data reception errors during Contention-Based (CB) access, leading to successive collisions when reallocating resources, as it mistakenly identifies packet reception errors as collisions, causing data retransmitted by multiple UEs to collide again.
Innovation Solution
A method and apparatus for transmitting and receiving data using CB access, where UEs determine a transmit power by adding a margin value to the required uplink power, and a Node B broadcasts an ACK message to prevent retransmissions in case of collisions, ensuring successful data reception by differentiating transmit powers among UEs and avoiding successive collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Node B reallocates resources in the same frequency location after detecting a packet reception error during HARQ operation, then the HARQ retransmission process can be performed, but successive collisions occur when multiple UEs retransmit data using the same CB grant
Solution Approach 1:
The patent changes the frequency location parameter for resource allocation by introducing an offset value. When a collision is detected during CB access, the Node B reallocates resources to a different frequency location (original frequency + offset) for HARQ retransmission, preventing successive collisions while maintaining reliable data reception
Solution Approach 2:
The patent implements a feedback mechanism where the Node B detects collisions during CB access and provides feedback by allocating resources with a frequency offset. This feedback loop allows the system to adapt resource allocation dynamically, preventing successive collisions and improving overall reception reliability
2Loss of time
If multiple UEs are assigned the same CB grant to transmit data, then the resource allocation time is reduced, but collisions occur and efficiency decreases
Solution Approach 1:
The patent dynamically changes the frequency location parameter based on collision detection. When collisions are detected in CB access, the system adjusts the resource allocation to use a different frequency location for retransmission, maintaining the speed benefits of CB access while improving transmission reliability
Solution Approach 2:
The patent introduces dynamic resource allocation where the frequency location for HARQ retransmission is not fixed but adjusted based on collision detection. This dynamic approach allows the system to adapt to varying channel conditions and collision patterns, maintaining efficiency while improving reliability
Data Source
AI summary
A method and apparatus is provided for transmitting and receiving data using a Contention-Based (CB) access to prevent successive collisions due to an HARQ operation and improve the probability of successful reception in a mobile communication system. In a method for transmitting data using a CB access, it is determined whether it is possible to transmit data provided from an upper layer to a Node B using a CB access method. If it is possible to transmit the data using the CB access method, a CB grant is acquired from the Node B. Upon acquiring the CB grant, a transmit power is determined by selecting a smaller value among a value obtained by adding a predetermined first margin value to an uplink power Required_uplink_power required to transmit the data, and a maximum transmit power of a UE.