On the receive end of the chain, the Keithley 2820 vector signal
analyzer (VSA) handles receipt and recovery of signals. It uses the
company’s MIMO Signal Analysis software for signal recovery,
measurement, and display. As many as four VSGs and VSAs may
be used together. In addition, any MIMO configuration up to 4x4
(e.g., 2x3, 4x3, 2x1) can be accommodated.
Keithley’s 2920 VSG can generate signals from 10 MHz to
6 GHz. An optional arbitrary waveform generator (AWG) lets
users produce modulating signals for GSM, EDGE, WCDMA,
cdma2000, single-input/single-output (SISO) wireless local-area
network (WLAN), the very demanding 40-MHz wide 802.11n
Wi-Fi signal, and WiMAX. The 2920 is also available as a standalone
test unit.
Meanwhile, the 2820 VSA receives signals up to 6 GHz. Bandwidth
is 40 MHz. It can receive, analyze, and display most popular
wireless standards such as those mentioned for the 2920, both
SISO and MIMO.
To use these instruments in a MIMO test system, you need the
2895 MIMO Synchronization Unit, which synchronizes all of
the VSGs and VSAs. It provides a common local-oscillator (LO)
output to all units, as well as a 100-MHz digital clock and trigger
signals to sync all of the units for the selected MIMO configuration.
The PC-based MIMO Signal Analysis software lets you test
and measure all standards with configurations to 4x4 MIMO.
Pricing begins at $17,500 for the 2920 VSG and at $22,500
for the 2820 VSA. The 2895 MIMO Synchronization Unit costs
$9900. MIMO signal analysis software is $9500.
Rohde & Schwarz offers several new LTE, WiMAX, and
MIMO products, too. One complete 2x2 MIMO test setup that
works with 3GPP LTE, WiMAX, 802.11 Wi-FI, and HSPA+
consists of the SMU200A RF signal generator and the AMU200A
baseband generator along with a fading simulator in one instrument
(Fig. 6). The instrument permits real-time fading measurement
on all four propagation paths.
A typical MIMO system employs the 2x2 format with two
transmitters and two receivers. The test setup requires two signal
generators and one fading simulator. R&S offers an option that
allows measurements on 2x2 MIMO receivers using a single
instrument. The generator can be equipped with an internal fading
simulator as well as two RF sources and two baseband sources.
When equipped with this option, the instrument can simulate the
four fading channels required.
R&S offers optional firmware for the SMU200A/AMU200A
combo. It adds channel coding and MIMO pre-coding for up to
four transmit antennas for 3GPP LTE. With it, users no longer
need external fading hardware or control software for testing
3GPP LTE mobile devices.
Since the signal generators provide 3GPP TS 36.211 standardcompliant
signals, the full scope of RF performance can be tested.
It requires additional instruments or an external PC for signal calculation.
Another option for the R&S SMU200A and some other
R&S generator models, the SMx-K55 software, offers downlink
and uplink testing functionalities.
R&S’s CMW500 LTE protocol tester makes testing basestations
and handsets easy despite the complexity of the LTE protocol
(Fig. 7). It has a frequency range up to 6 GHz with a bandwidth of
40 MHz, and it greatly facilitates conformance, performance, and
interoperability tests. A full suite of tested software tools and test
sequences greatly reduces LTE development efforts.
As for a WiMAX test solution, R&S’s CMW270 communications
tester emulates a basestation. It’s a great testing solution for
chip sets and mobile stations, combining signal generation and
signal analysis in one box. It supports the 802.16e mobile WiMAX
standard and covers from 100 MHz to 6 GHz. The instrument
also supports all RF profiles defined by the WiMAX Forum.
Tektronix Communications recently announced some LTE
and WiMAX test platforms. For instance, its G35 comprehensive
network management and diagnostics solution covers all protocol
layers and physical interfaces, including air and fixed line interfaces (Fig. 8). It includes the G35-LTE functional
and load test platform and the NSALTE
scalable platform for monitoring,
troubleshooting, and optimization.
Tektronix also has a WiMAX version
of the G35. The WiMAX Forum recently
selected this version as the test solution to
verify the interoperability of WiMAX network
nodes in mobile WiMAX certified
test labs around the world.
Although not an LTE or WiMAX test
product, the Tektronix H600 RFHawk
handheld digital RF signal hunter is designed
for the surveillance and security market (Fig.
9). Its receiver contains a high-performance
spectrum analyzer with an intuitive set of
user controls, allowing for the quick and
simple classification and location of both
analog and digital RF transmissions.
Finding and physically locating RF
emitters that are misusing the radio spectrum
can be a challenge, especially when
risk mitigation and time to response are
critical. Many covert signals are designed to
avoid detection by hiding among legitimate
transmissions. The RFHawk was developed
based on customer needs to quickly spot
and locate illegitimate analog and digital
RF transmission sources
Its spectrogram mode lets customers see
the true signal shape through FFT-based
spectrum analysis. The RFHawk uses a
DSP technique called spectral correlation
analysis to look at internal frequencies
within the signal to discover a digital signal’s
symbol rate and other repetitive internal
rates to identify valid signals.