Massive MIMO Transmitter Array Hardware Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Massive MIMO systems face increased hardware complexity and energy consumption due to the need for numerous antennas and RF chains, which counteract the benefits of beamforming, especially in channels with small angular spread.
Innovation Solution
Implementing resource sharing techniques, such as code-division multiple access (CDMA), to reuse digital-to-analog converters (DACs) and reduce the number of RF chains by encoding and decoding signals with orthogonal binary codes, allowing multiple RF chains to share hardware components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of antennas and RF chains is increased to achieve massive MIMO beamforming, then beamforming gain and signal-to-noise ratio are improved, but hardware complexity and energy consumption increase
Solution Approach 1:
Multiple RF chains share common hardware resources including a single digital-to-analog converter (DAC), power amplifier (PA), and antenna. The digital beamforming signals from multiple RF chains are combined in the digital domain before conversion to analog, eliminating the need for separate analog processing chains for each antenna element.
Solution Approach 2:
A single DAC serves multiple RF chains by receiving combined digital beamforming signals that contain information for multiple antennas. The shared DAC converts the aggregated digital signal to analog, which is then distributed to multiple RF chains through analog switching and combining networks, allowing one component to perform functions that would traditionally require multiple dedicated components.
2Manufacturing precision
If the number of DACs is increased to match the number of antenna elements, then digital beamforming precision is improved, but cost and device complexity increase
Solution Approach 1:
Multiple digital beamforming signals from different RF chains are combined in the digital domain before being fed to a single DAC. The digital combining process preserves the precision requirements of digital beamforming while eliminating the need for multiple high-resolution DACs, as the combined signal contains all necessary information for reconstructing multiple antenna outputs.
Solution Approach 2:
The single DAC output is effectively copied and distributed to multiple RF chains through analog switching and combining networks. Rather than having each antenna element receive a dedicated DAC output, the same analog signal from the single DAC is routed and combined to serve multiple antennas, reducing hardware while maintaining functionality.
Data Source
AI summary
A transmitter including radio-frequency (RF) chains. Each RF chain includes a power amplifier, a band-pass filter, and an antenna for transmitting an analog signal using a beamforming with an angle of departure (AOD) defined by phase shifts of the analog signals transmitted by the RF chains. A processor to determine digital signals for transmission from the RF chains. Wherein there is one-to-one correspondence between a digital signal and an RF chain. An encoder to encode the digital signals with binary codes to produce a set of encoded digital signals and to combine the encoded digital signals into a combined digital signal. A digital-to-analog converter to convert the combined digital signal into an analog domain to produce a combined analog signal. A decoder to decode, using the binary codes, the combined analog signal into a set of analog signals and to submit the analog signals into the corresponding RF chains.