With the drive of always on connectivity and the launch of commercial LTE networks starting to happen across the globe, systems integrators are now looking towards LTE modems as methods of providing wireless high speed always on connectivity. With the evolution of new technology comes new technological challenges which have always been there with 2G and 3G technology but become more complicated with LTE.
We here-under publish an interesting article written by Stuart Thomas from RFI on the challenge of integrating the new LTE modules into M2M applications:
The four main areas of concern for systems integrators of wireless modules are: Power supply, antenna design, USIM interface performance and application software for driving the modem.
The most challenging area out of these four is the antenna design and with the large number of commercial frequency bands available globally this will present a large challenge for products entering the global market as there will need to be hardware specific configurations for each region and/or intended market. Figure 1 below plots the number of frequency bands recognised by 3GPP and commercially available or planned in the different technology areas.
With the wide range of operational frequencies specified for LTE, antenna hardware designs and performance is going to be the major challenge for systems integrators using these modules and selling products to the global market which is divided by frequency bands. Figure 2 below shows these frequency bands (as of January 2011).
The two key measurements that are closely related to the antenna design are Radiated Spurious Emissions (RSE) and Over the Air Antenna Performance (Commonly known as OTA).
Both of these requirements are now being fully defined in organisations such as 3GPP and CTIA Wireless for LTE. The specific references are defined below in Table 1.
|Measurement||Specification (LTE Specific)|
|Radiated Spurious Emissions||3GPP TS36.124|
|Over the Air Antenna Performance||3GPP TS37.976|
CTIA Over the Air Performance Test Specification
In the area of OTA there are some special considerations to be considered in relation to multiple antenna configurations and while these specifications will detail all the requirements for configurations such as SISO, SIMO, MISO and MIMO.
The fact that multiple input and/or output antenna configurations will be implemented brings additional challenges in the implementation of them, such as achieving low envelope correlation between antennas, while achieving large individual antenna mean effective gain and within a small device.
Measurement of multiple antenna configurations is going to be critical for successful deployment of LTE connected devices. RFI as a specialist test and consultancy business is rapidly gearing up to provide these services and assessment needs enabling successful LTE device deployments.