Spatial Modulation Using Null Beams for Channel Capacity
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Solution Overview
Problem
Existing spatial modulation techniques in multi-antenna systems face limitations in enhancing channel capacity and complexity ratio, particularly in RASK and RSM methods, where the number of receiving antennas restricts transmission capacity.
Innovation Solution
A method that involves prefiltering binary sequences towards target antennas and using the deliberate absence of focusing or power modulation to encode information, allowing for simultaneous transmission of multiple binary sequences across multiple antennas, thereby increasing channel capacity without activating all beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial modulation techniques (RASK, RSM) are implemented with multiple receiving antennas, then transmission capacity increases, but the ratio between implementation complexity and channel capacity deteriorates
Solution Approach 1:
The patent inverts the conventional spatial modulation approach by using the absence of focusing (null beams) as the active information-carrying mechanism rather than the presence of beams. Instead of activating specific antennas to transmit information, the system deliberately creates nulls (zero or reduced power) towards specific receiving antennas during predetermined symbol times. This inversion allows the system to encode information in the spatial nulls, effectively turning the 'absence' of signal into the 'presence' of information, thereby increasing channel capacity without proportionally increasing implementation complexity
Solution Approach 2:
The patent segments the transmission process into distinct phases: predetermined integer k of symbol times for transmitting absence of focusing information, and subsequent symbol times for transmitting binary sequences with focusing. This segmentation allows the system to separately handle different types of information encoding (spatial nulls vs. conventional focusing), optimizing the complexity-capacity ratio by dividing the transmission task into manageable segments with different encoding strategies
2Productivity
If deliberate absence of focusing is used to encode information during predetermined symbol times, then channel capacity increases, but transmission protocol complexity increases
Solution Approach 1:
The patent applies preliminary action by establishing predetermined patterns for the absence of focusing before transmission begins. The system pre-defines which receiving antennas will receive nulls during specific symbol times, creating a structured framework that simplifies both transmission and reception. This preliminary arrangement allows the receiver to anticipate and efficiently decode the information carried by spatial nulls without requiring complex real-time processing, thereby increasing channel capacity while controlling protocol complexity through pre-planned transmission structures
3Productivity
If power modulation is used to encode additional information, then transmission capacity increases, but energy consumption increases
Solution Approach 1:
The patent applies partial action by using power modulation selectively rather than continuously. The system modulates power levels (including zero power for null beams) only during specific symbol times and for specific beams, rather than modulating all beams continuously. This partial application of power modulation allows the system to encode additional information (increasing transmission capacity) while minimizing energy consumption by avoiding unnecessary power modulation during periods when information is transmitted through other means (such as spatial nulls or conventional focusing)
Data Source
AI summary
Some embodiments are directed to a method of transmission from at least one transmit antenna to all or some of n reception antennas including at least one transmission step suitable for transmitting a first binary information item by using the absence of focusing from the transmit antenna to any one of the n reception antennas, during a predetermined integer number k of symbol times and/or a modulation of the power transmitted by at least one transmit antenna, participating in a coding of a second binary information item. Some other embodiments are directed to a receiver-decoder suitable for reception according to the method.