Beamforming Engine True Time Delay via Crossbar Switch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing beam forming systems face challenges in providing true time delay in a computationally efficient manner, especially in wideband applications, as phase shifters are not suited for such scenarios and complex digital circuits required for true time delay often exceed the resources of a single processor.
Innovation Solution
A system comprising a deserializer, zero-insertion block, crossbar switch, and polyphase digital downconverter is used to achieve true time delay, where the crossbar switch applies fine delay control through circular shifts and adjustable major delay blocks, allowing for efficient processing without the need for complex multiplications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex digital circuits (FIR filters, convolution circuits) are used to implement true time delay, then true time delay functionality is achieved, but FPGA resource requirements become excessive and may not fit on a single processor
Solution Approach 1:
The patent segments the true time delay function into two distinct components: a major delay block that provides coarse delay adjustment in increments of one clock cycle, and a polyphase filter that provides fine delay adjustment through fractional delay. This segmentation allows each component to be implemented with simpler, more resource-efficient circuits rather than requiring a single complex FIR filter or convolution circuit.
Solution Approach 2:
The patent changes the approach from implementing true time delay through complex digital filtering to using a combination of integer-cycle delays and fractional delays. The polyphase filter uses a set of pre-computed tap coefficients that are selected and combined based on the desired delay value, transforming the problem from real-time complex computation to table-lookup and addition operations that are much more resource-efficient in FPGA implementations.
2Ease of operation
If phase shifters are used in beam forming systems, then beam steering is achieved in narrowband applications, but beam squint occurs in wideband applications reducing performance
Solution Approach 1:
The patent substitutes the phase shifter mechanism with a true time delay mechanism. Instead of adjusting phase shifts that cause beam squint in wideband applications, the system uses time delay elements (major delay block and polyphase filter) that provide frequency-independent delay. This replacement eliminates the beam squint problem while maintaining beam steering capability across wide bandwidths.
3Measurement precision
If true time delay is implemented using traditional digital approaches, then accurate delay is achieved, but computational complexity and processing time increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-computing the polyphase filter tap coefficients offline and storing them in lookup tables. During operation, the system only needs to select the appropriate tap coefficients and perform simple additions, rather than computing complex convolution operations in real-time. This preliminary preparation significantly reduces processing time while maintaining high delay accuracy.
Data Source
AI summary
A system for beamforming employing true time delay. The system includes a deserializer configured to receive a serial data stream and to convert the serial data stream into a plurality of parallel data streams, a zero-insertion block configured to insert zeroes into each of the parallel data streams, and a crossbar switch having a plurality of inputs and an equal number of outputs. The inputs are connected to the zero-insertion block, each of the outputs corresponding to one of the inputs. The crossbar switch is configured, in a first state, to connect each output to the corresponding input, and in a second state, to connect each output to an input different from the corresponding input, the set of outputs being a circular shift of the set of inputs.