IEEE Circuits and Systems Magazine - Q1 2021 - 61

V. Processing Platforms for Vital Sign detection
Several signal-processing platforms have been adopted
for human vital sign detection. The most common platforms are: Central processing unit (CPU) of a PC, digital
signal processor (DSP) unit, Graphic processing unit
(GPU), application specific integrated circuits (ASIC)
based processors, and field programmable gate array
(FPGA). Besides these processing devices, the algorithm used also determines the processing speed, cost,
resources utilization, and accuracy.
When real-time processing is not required, the computational analysis can be performed on a CPU. On the
contrary, when real-time processing is required, it will
be challenging for the CPU to meet requirements such
as high throughput, low latency, low resources utilization, and low power consumption. To overcome those
challenges for radar based real time human vital signs
detection, dedicated hardware implementations, such
as ASIC or FPGA have been chosen by researchers in
literature [68].
Another factor in considering the type of processing
platform is whether it will be used for simultaneous control and/or processing. If the processing is performed
using a PC platform, then the algorithms are coded using software such as MATLAB or LabVIEW and are executed in the CPU. A separate set of tools and software
is used when the processing is performed on an FPGA
using hardware description languages such as VHDL or
Verilog. Table 7 summarizes the state-of-the-art signal
processing platforms for detecting human vital signals.
The choice of hardware (such as DSP boards, GPUs,
microcontrollers or FPGAs) and consequently, the overall
system's implementation costs, are dependent on factors
such as the radar architecture, detection techniques chosen, and whether these techniques and/or algorithms require parallel or serial processing. Moreover, factors such
as the hardware functionalities (and limitations) and the
number of hardware to fully and efficiently implement the
intended system functionalities also need to be considered for cost-efficiency. Their relative per unit costs are
typically low to high, listed in the following order: microcontrollers, DSP boards, FPGAs and GPUs. It is also noted
that product range in each of the hardware exists with
varying capabilities and subranges in costs. In many instances, FPGA's are used as verifications tool, whereas in
other instances, depending on the application, they also
can be used as central processing unit. This can be tied
to the cost effectiveness, for example, by using a single
central processing unit instead of linking each radar with
as separate processor to lower the cost of implementing
the overall system.
In [51], a DSP and microcontroller unit were used as
processing platforms, while in [29], a microcontroller is
FIRST QUARTER 2021

used for digitization and a PC is used for further processing. Besides this, the work in [4] is performed based
on SoC and PC processing, while [69] is based on FPGA
and GPU processing. Moreover in [30], only a DSP core
is used, and in [42] only an SoC is used. As can be seen
from Table 7, vital sign detection can be performed on
hybrid platforms, or on a single processor type, such as
FPGA, PC, or DSP. The table also classifies the researches in which FPGA was applied, into two categories: (i)
radar with FPGA used as processing platform, and solution is specifically targeted for vital signs detection; or
(ii) radar with FPGA used as processing platform, but
its application is not specifically targeted for vital signs
detection. However, for the latter, the FPGA architecture
and implementation can be modified or extended for application in vital signs detection. The classification of
literature based on the processing platform is particularly useful when determining specific platforms for the
implementation of different algorithms.
FPGA has been widely used to implement algorithms
on hardware, to confirm their accuracy and to ensure
effective real time analyses [62]. The reconfigurable nature of an FPGA offers a multifunction implementation,
resulting in resource efficiency compared to separate
implementations of functions on an ASIC-based processing platform, for instance. In addition to that, its cost-efficiency and reconfigurability makes it a preferred rapid
prototyping platform for researchers [69].
The use of FPGA as a processing platform in the area
of radar systems has been increasing steadily. Table 8

Table 7.
Summary of radar and/or vital sign detection
processing platforms in literature.
Platform

Reference

PC

[3], [20], [22], [23], [25], [26],
[28], [37], [35], [7], [38], [39],
[55], [56], [57], [70], [71]

FPGA

[2], [21], [31], [54], [40], [43],
[44], [45], [49], [62], [72],
[73], [74], [75], [76]

FPGA (not specifically for
vital sign detection)

[52], [53], [68], [77], [78],
[79], [80], [81], [82], [83], [84]

SoC

[42]

DSP

[30]

FPGA-GPU

[69]

PC-microcontroller

[29], [27]

DSP-microcontroller

[51]

SoC-PC

[4], [1]

No focus on the processor

[8], [9], [10], [32], [33], [34],
[46], [47], [48], [50]
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