Multi-Carrier Transmitter Single RF Chain Architecture
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Solution Overview
Problem
Existing wireless communication systems face challenges in supporting multiple frequency channels efficiently, leading to increased design complexity and cost due to the need for multiple RF transmit chains.
Innovation Solution
A multi-carrier transmitter design that utilizes a single wideband RF transmit chain to simultaneously transmit up to T signals on up to T frequency channels, employing processors to generate, filter, and upconvert signals, and perform pre-distortion to compensate for gain and phase mismatches, ultimately generating an RF output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple RF transmit chains are used to support multiple frequency channels, then the data transmission capacity is improved, but the device complexity and cost increase substantially
Solution Approach 1:
The patent combines multiple frequency channel transmissions into a single RF transmit chain by digitally modulating multiple data channels and multiplexing them before analog conversion. This merging approach allows simultaneous transmission on multiple frequency channels while using only one RF transmit chain, thereby maintaining data transmission capacity without increasing device complexity or cost.
Solution Approach 2:
The single RF transmit chain is designed to perform multiple functions by handling multiple data channels and multiple frequency channels simultaneously. The digital signal processing components enable the system to dynamically allocate and modulate multiple channels through one universal RF path, replacing the need for dedicated RF chains for each channel.
2Productivity
If multiple RF transmit chains are used to support multiple frequency channels, then the data transmission capacity is improved, but the power consumption increases
Solution Approach 1:
By merging multiple channel transmissions into a single RF transmit chain, the system eliminates redundant power consumption associated with multiple separate RF chains. The digital multiplexing and single analog conversion path reduce overall energy usage while maintaining the capability to transmit on multiple frequency channels simultaneously.
3Device complexity
If a single RF transmit chain is used to transmit multiple frequency channels, then the device complexity and cost are reduced, but gain and phase mismatches occur in analog quadrature upconversion
Solution Approach 1:
The system performs preliminary digital pre-distortion and pre-correction on the I and Q signal paths before analog quadrature upconversion. By anticipating and compensating for potential gain and phase mismatches in the analog domain, the digital preprocessing ensures accurate frequency channel separation and transmission, thereby maintaining manufacturing precision despite using a single RF transmit chain.
Solution Approach 2:
The system incorporates feedback mechanisms to detect and correct gain and phase mismatches in the analog quadrature upconversion path. By monitoring the actual performance and adjusting digital compensation parameters, the system maintains high precision in frequency channel transmission while using a cost-effective single RF chain architecture.
Data Source
AI summary
A multi-carrier transmitter capable of transmitting on one or multiple frequency channels simultaneously is described. In one design, the multi-carrier transmitter includes at least one processor and a single radio frequency (RF) transmit chain. The processor(s) may generate output chips for each of multiple frequency channels, digitally filter and upsample the output chips for each frequency channel to obtain filtered samples, and digitally upconvert the filtered samples for each frequency channel to a different frequency to obtain upconverted samples. The processor(s) may then combine the upconverted samples for the multiple frequency channels to obtain composite samples, perform pre-distortion on the composite samples for I/Q mismatch compensation, and upsample the pre-distorted samples to obtain output samples. The output samples may be converted to an analog signal with a wideband DAC. The RF transmit chain may process the analog signal to generate an RF output signal.