Channel Multiplexing for Narrowband LTE Uplink Capacity
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Solution Overview
Problem
Narrowband LTE technologies, such as Cat-M1, face inefficiencies in radio resource utilization due to repetitive data transmissions by user equipment (UEs), which prevent other UEs from transmitting, leading to delayed communications and suboptimal use of available resources.
Innovation Solution
Implementing channel multiplexing by assigning orthogonal patterns to multiple UEs to transmit repetitive data using the same set of radio resources, allowing the base station to differentiate and decode data from each UE, thereby enhancing resource efficiency and reducing transmission delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single UE uses a set of radio resources for repetitive data transmission, then transmission reliability is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent combines multiple UEs' repetitive transmissions into a single time-frequency resource by merging their signals through orthogonal coding. Multiple UEs are assigned orthogonal sequences (e.g., Walsh codes) that allow their signals to be transmitted simultaneously on the same physical uplink shared channel (PUSCH) resources while remaining distinguishable at the base station through correlation processing.
Solution Approach 2:
The patent introduces a new dimension of orthogonal coding sequences to differentiate between multiple UEs transmitting on the same radio resources. Instead of allocating separate time-frequency resources to each UE, the system adds a code domain dimension where each UE is assigned a unique orthogonal sequence, transforming the resource allocation from spatial/time-frequency separation to code-domain separation.
2Object-affected harmful factors
If radio resources are allocated to one UE at a time, then interference between UEs is avoided, but transmission delay increases
Solution Approach 1:
The patent introduces orthogonal sequences as an intermediary mechanism that enables multiple UEs to share the same radio resources without direct interference. These sequences act as mathematical filters that allow the base station to separate and decode individual UE signals from the combined transmission, effectively mediating the interaction between multiple UEs on shared resources.
3Productivity
If multiple UEs share the same radio resources simultaneously, then resource efficiency improves, but signal differentiation becomes difficult
Solution Approach 1:
The patent applies local quality by assigning unique orthogonal sequences to different UEs, giving each signal a distinct local characteristic (code pattern) while transmitting on the same global radio resources. This allows the base station to differentiate between UEs by processing the local code-specific properties of each signal through correlation detection.
Data Source
AI summary
A base station may receive repetitive data transmitted using a particular set of radio resources The base station may apply a first orthogonal pattern, assigned to a first user equipment (UE), to a segment of subframes of the received repetitive data. The base station may apply a second orthogonal pattern, assigned to a second UE, to the segment of subframes of the received repetitive data. The base station may determine first repetitive data, transmitted by the first UE using the particular set of radio resources, based on applying the first orthogonal pattern to the segment of subframes of the received repetitive data. The base station may determine second repetitive data, transmitted by the second UE using the particular set of radio resources, based on applying the second orthogonal pattern to the segment of subframes of the received repetitive data.