Wireless UE Overloading With CDM Signatures for Satellite Capacity
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Solution Overview
Problem
The challenges of applying MIMO techniques in satellite communication systems with limited degrees of freedom, such as long round-trip delay, high Doppler shift, and power-limited environments, hinder the efficient use of MIMO techniques for increasing channel capacity and coverage.
Innovation Solution
A method involving data and UE overloading using code division multiplexing (CDM) with Walsh Hadamard codes and non-orthogonal codes to map multiple UEs and data streams, optimizing overloading signatures to minimize cross-correlation and enhance coverage and capacity without altering hardware or software significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MIMO techniques are applied in satellite communication systems, then channel capacity and coverage can be increased, but the limited degrees of freedom (long round-trip delay, high Doppler shift, power-limited environment) hinder efficient use of MIMO techniques
Solution Approach 1:
The patent changes the fundamental parameter of multiplexing approach from spatial (MIMO) to code-domain (CDM with overloading). By using Walsh Hadamard codes and optimized overloading signatures, the system achieves capacity increase through code separation rather than spatial multiplexing, adapting to satellite constraints.
Solution Approach 2:
The patent substitutes the mechanical/spatial MIMO system with a code-based CDM system. Instead of relying on multiple antennas and spatial degrees of freedom, the system uses code division multiplexing with optimized signatures to achieve similar capacity goals while accommodating satellite communication limitations.
2Quantity of substance
If multiple UEs are overloaded using CDM scheme, then the number of simultaneously accessible channels increases, but cross-correlation between codes may increase causing interference
Solution Approach 1:
The patent optimizes code parameters by selecting specific Walsh Hadamard codes and designing overloading signatures with minimized cross-correlation properties. This parameter optimization allows more UEs to be multiplexed while controlling interference levels.
Solution Approach 2:
The patent converts the potentially harmful cross-correlation effect into a beneficial structure by using optimized overloading signatures where controlled cross-correlation patterns are exploited rather than avoided, enabling efficient separation of overloaded UEs at the receiver.
3Adaptability or versatility
If satellite network characteristics (long round-trip delay, high Doppler shift) are considered, then compatibility with terrestrial radio interfaces can be maintained, but the efficiency of MIMO techniques decreases
Solution Approach 1:
The patent creates a universal communication framework where the same code-based overloading framework can be applied to both terrestrial and satellite networks. The CDM scheme with optimized signatures provides multi-functionality, working across different propagation environments without requiring separate system designs.
Data Source
AI summary
A method of a base station may comprise: mapping at least one port of the base station to each of a plurality of user equipments (UEs) to be overloaded; configuring overloading signatures for a code division multiplexing (CDM) scheme; mapping the overloading signatures with the plurality of UEs to be overloaded, respectively; transmitting a message including configuration information of the overloading signatures to the plurality of UEs; and transmitting, to the plurality of UEs, signals multiplexed by the CDM scheme using the overloading signatures.