Final report on link level and system level channel models - Winner

WINNER D5.4 v. 1.4
Sampling frequency 320 MHz at Tx and Rx
Propagation delay resolution
4.17 ns (1/bandwidth)
Impulse response length 0.8 µs – 25.6 µs adjustable to the
environment
RF sensitivity
Max. meas. data storage rate
-90 dBm
2x160 Mbytes/s
The RUSK Channel Sounder uses an excitation signal concept, which is known as the “periodic multisine
signal”. This approach is well known from frequency domain system identification in measurement
engineering. In communication engineering teRMS this signal may be called a multicarrier spread
spectrum signal (MCSSS). Regarding the overall spectral shape, the main advantage of multicarrier
spread spectrum signal (MCSSS) is its “brickwall-type” shape which allows concentrating the signal
energy exactly to the band of interest. This can even be multiple bands when spectral magnitudes are set
to zero. One example application is FDD sounding, which means that the sounder simultaneously excites
both the up- and the down-link band. Figure 5.3 presents the MCSSS in time (top row, left) and frequency
domain (top row, right).
Figure 5.3: Broadband multicarrier spread spectrum signal (MCSSS) magnitude in the time and
frequency domain (top row) and estimated CIR and received signal spectrum (bottom row).
In case of multipath transmission, the power spectrum of the received signal is shaped by frequency
selective fading as shown for example in Figure 5.3 (bottom row, right). Furthermore the impulse
response (bottom row, left), which would result from inverse Fourier transform of frequency response, is
shown in the same figure.
A MIMO channel sounder measures the channel response matrix between all M Tx antennas at the transmit
side and all M Rx antennas at the receiver side. This could be carried out by applying a parallel multiple
channel transmitter and receiver. However, true parallel systems not only are extremely expensive. They
are also inflexible (when considering changing the number of antenna channels) and susceptible to phase
drift errors. Also parallel operation of the transmitter channels would cause specific problems since the
M Tx transmitted signals have to be separated at the receiver. A much more suitable sounder architecture is
based on switched antenna access. A switched antenna sounder contains only one physical transmitter and
receiver channel. Only the antennas and the switching channels are parallel. This reduces the sensitivity to
channel imbalance.
Figure 5.4 shows the switching time frame of a sequential MIMO sounder using antenna arrays at both
sides of the link, which is applied in the RUSK MIMO Channel Sounder. Any rectangle block in the
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