LTE PUCCH Interference Randomization via Prime-Modulo Remapping
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Solution Overview
Problem
In the LTE system, interference among UEs multiplexed in the same PUCCH resource block is not adequately randomized, leading to orthogonality damage due to channel fading and Doppler shifts, resulting in severe interference, especially when UEs use the same or adjacent cyclic shifts of CAZAC sequences.
Innovation Solution
The method involves remapping control channel resources for UEs in the second timeslot using prime-modulo operations, ensuring different resource indexes for UEs in the first and second timeslots, and adjusting orthogonal codes and cyclic shifts to maintain orthogonality, thereby equalizing and randomizing interference among UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If UEs use the same or adjacent cyclic shifts of CAZAC sequences in the same PUCCH resource block, then the number of multiplexed UEs increases, but orthogonality damage occurs due to channel fading and Doppler shifts, resulting in severe interference
Solution Approach 1:
The patent applies frequency hopping in the second timeslot to dynamically change the resource allocation of UEs. By remapping control channel resources using prime-modulo operations, the system makes the control channel resources variable rather than fixed, which randomizes interference and maintains orthogonality under varying channel conditions
Solution Approach 2:
The patent changes the resource index parameters in the second timeslot based on the resource index in the first timeslot using the formula n_PRB(2) = (n_PRB(1) + delta) mod N_RB. This parameter transformation ensures that UEs experience different resource allocations in the second timeslot, equalizing interference and maintaining orthogonality despite channel fading and Doppler shifts
2Ease of manufacture
If fixed time-frequency resources are allocated to PUCCH, then resource allocation is simple, but interference among UEs is not randomized, leading to severe interference under channel fading and Doppler shifts
Solution Approach 1:
The patent introduces dynamic resource allocation through frequency hopping in the second timeslot. The resource index is transformed using prime-modulo operations, making the allocation variable rather than fixed. This dynamic approach randomizes interference patterns while maintaining systematic control
Solution Approach 2:
The patent implements periodic frequency hopping between the first and second timeslots. This periodic resource remapping creates a structured pattern of interference randomization, where the resource allocation changes in a predictable yet interference-randomizing manner across different timeslots
Data Source
AI summary
A method for interference randomization of physical uplink control channel (PUCCH), which is used in long term evolution (LTE) system, when multiple terminals multiplex PUCCH to transmit uplink control signalings, the difference of index of control channel resource used by any two terminals in the first timeslot of PUCCH is different from the difference of index of control channel resource used by the two terminals in the second timeslot of PUCCH. The invention can realize interference randomization between UEs that multiplex the same PUCCH.