The use of multiple input multiple output or MIMO complicates the process of measuring eNodeB power and modulation quality in LTE systems. Spectrum analyzers only have one receiver whereas two or more receivers are needed for complete demodulation of data traffic channels. Connecting directly to each transmitter in turn is not necessarily the solution because of traffic pre-coding techniques causing similar measurement constraints, and may not even be possible because of site accessibility issues or because of the use of remote radio heads.
Anritsu solves these problems by measuring the LTE control channels "over-the-air" providing a quick and convenient health check of the MIMO installation. The advantage is that measurements can be done unobtrusively and only if the health check shows potential problems need the site be taken off-air for further investigation. The LTE options available for Anritsu’s handheld analyzers measure the Physical Broadcast Channel, or PBCH, under MIMO conditions. MIMO signals are automatically detected and the modulation quality measurement or EVM switches to the PBCH.
MIMO and Remote Radio Heads complicate LTE eNodeB transmitter measurements, but these complications can be overcome by measuring the LTE control channel signals. When combined with a throughput check, the Anritsu LTE Measurement Suite, and especially the Tx Test measurement, provides an excellent tool for ensuring that LTE MIMO systems are working properly, even while operating with live traffic. This reduces the time and cost required for troubleshooting while reducing service disruptions.
For more details, go to Anritsu.com and download the "Practical eNodeB Transmitter Measurements for LTE and TD-LTE Systems Using MIMO" application note.