Uplink Cyclic Shift Allocation for Increased User Capacity
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Solution Overview
Problem
Conventional LTE systems are limited in accommodating a large number of users in uplink transmission due to the constraint of 12 cyclic shifts per resource block, resulting in a maximum of 12 orthogonal users per resource block, which restricts the overall capacity.
Innovation Solution
The method involves selecting regions of subcarriers where channel values vary gradually, skipping certain cyclic shifts to reduce interference, and using a processor to perform channel estimation and data detection, allowing for more users to be accommodated by utilizing cyclic shifts that are periodic over multiple resource blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional LTE systems use 12 cyclic shifts per resource block, then orthogonal users per resource block is limited to 12, but network capacity and number of accommodated users is restricted
Solution Approach 1:
The patent segments the cyclic shift resource by dividing it into two independent dimensions: intra-resource-block cyclic shifts (0-11) and inter-resource-block cyclic shifts (0-3). This segmentation allows users to be allocated cyclic shifts across multiple resource blocks, effectively increasing the total number of orthogonal users from 12 to 48 per resource block while maintaining manageable complexity through structured allocation.
Solution Approach 2:
The patent introduces a new dimension for cyclic shift allocation by extending the cyclic shift index from a single dimension (0-11 within one resource block) to two dimensions (intra-RB cyclic shift 0-11 and inter-RB cyclic shift 0-3). This dimensional expansion allows the system to accommodate more users by utilizing cyclic shifts across multiple resource blocks in the time domain.
2Quantity of substance
If more users are accommodated by extending cyclic shifts across multiple resource blocks, then network capacity increases, but interference management becomes more challenging
Solution Approach 1:
The patent applies local quality by ensuring that each user's cyclic shift allocation is optimized for their specific channel conditions. The base station determines the number of inter-resource-block cyclic shifts based on individual user requirements and channel characteristics, allowing tailored interference management for each user while maintaining overall system capacity.
Solution Approach 2:
The patent dynamically adjusts the parameter of cyclic shift allocation by allowing the base station to determine the number of inter-resource-block cyclic shifts (0-3) based on system conditions and user requirements. This parameter flexibility enables adaptive interference management while maximizing the number of accommodated users.
Data Source
AI summary
A method for accommodating users in an uplink channel is provided. The method comprises a processor for selecting a region of sub carriers in a frequency domain, wherein a channel value of a plurality of users over the selected region varies gradually. The processor is further configured to select the sub carriers within the selected region of sub carriers by skipping the sub carriers by an integer value which is 0 or more than 0. A product of a known sequence and an exponential sequence is transmitting over the selected sub carriers, wherein the exponential sequence is characterized by a cyclic shift value. Further, a base station is configured to perform channel estimation of the users using the received selected sub carriers within the selected region and the processor is also configured to perform data detection for the users over the selected sub carriers using the estimated channel value.