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Many operators have credited performance as a defining element in the successful deployment of their network. Early adopter performance test programs have been designed to consider a wide range of performance issues, from data throughput speed, voice quality and battery life, to signalling efficiency, latency and antenna sensitivity. Performance testing is an obvious and critical necessity, especially when one considers that LTE’s primary selling point is its superior levels of quality and performance.
It is through comprehensive lab-based device and network equipment performance testing, which replicates real-world environments and scenarios, that help suppliers to provide their customers with superior quality devices that work as expected on their chosen network. This helps improve customer satisfaction and thus assures brand loyalty.
Key performance items that need to be considered include signalling, audio quality and antenna and radio performance.
Data rate and throughput: Service providers need to assess data rates and throughput, critical aspects of device and consumer performance. Peak data rates, which are often perceived as the actual data rates a subscriber will experience, are far from reality. Peak data rates do not take into account factors like traffic load, fading, attenuation loss and the signal-to-noise ratio that all have an impact on the actual subscriber data rate and throughput performance.
LTE-A standards will enable data rates of up to three gigabits per second per sector: This will deliver the equivalent of a fixed-line broadband experience to the end user. Achieving data rates up to 3 Gbps over a mobile network poses a huge challenge for the wireless industry and will require thorough pre- (and post-) deployment testing to ensure maximum throughput and end-user satisfaction.
Interoperability: New devices must continue to interoperate with pre-existing legacy standards. As new technologies and standards are introduced there is an increased opportunity for things to go wrong and it is imperative that LTE equipment is still able to operate on legacy standards, when necessary. Additionally, spectrum resources are scarce and different countries have unique frequency band availability for LTE, which currently has 18 operational frequency bands and could potentially make use of more than 40 bands. LTE equipment will need to undergo performance testing to ensure that it can work effectively across several networks and in various countries and also in non-contiguous frequency bands. This capability is essential to support data roaming, not just between LTE networks that have a limited footprint at present, but across legacy networks to ensure that users have a consistent mobile data experience.
Signalling: The number of subscribers and applications are increasing. This, in turn, is generating huge amounts of data and signalling traffic between the handset and the network. With so many users and applications now available, it is imperative that service providers have a better understanding of the potential impact that mobile applications will have on the performance of a device and the capacity in their network. Oracle estimates that global LTE Diameter signaling traffic will increase at a 140% compound annual growth rate, from 1.2 million messages per second in 2012 to 99 million MPS by 2017.
Audio quality: Although LTE has been predicated on the promise of high-speed mobile broadband access, subscribers will still expect to make voice calls on their devices so audio quality needs to be assured. Poor audio quality would also degrade the experience of video calling. The success of services like HD voice and voice over LTE are dependent on device and network performance that can be assessed by on-going LTE performance testing. Audio quality is a critical component of this testing.
Multiple antenna and radio configurations: With the advent of LTE, many new MIMO antenna configurations have become part of the standard and, therefore, the testing regime. All of these configurations must be tested under varying RF conditions and parameters and inclusive of the antennas (using over-the-air testing techniques). Although these test configurations add new complexity to the testing domain, they also provide additional performance measurements to ensure quality of service.
In order to quantify and qualify the key performance considerations of throughput, interoperability and radio/antenna performance, it is necessary to establish a testing environment and methodology that produces precise, repeatable and reliable results. The testing environment and associated testing methodologies must be highly flexible and re-configurable to accommodate the expanding number of test configurations. It must be capable of managing a large number of variable parameters and permutations and isolation of variables. These variables include items such as frequencies, power levels, channel bandwidths, radio technologies, RF channel conditions (e.g. delay, propagation, channel models, noise) and network loading conditions.
Critically important is the need to provide a high level of automation, so that tests can cycle through numerous iterations of variables, channel/network conditions and configurations unattended. Automation enables 24-hour testing and provides cost and time efficiencies when compared to manual testing. Ultimately, the test environment needs to replicate/recreate, as near as possible, the real-world environment, conditions and performance of the device that the user experiences.
A controllable, repeatable and flexible test environment can only be delivered through laboratory testing. The explosive growth of wireless data, brought about by the rapid deployment of LTE networks and the proliferation of smartphones, has introduced both challenges and opportunities to chipset, device, network suppliers and operators. Their savvy customers are quick to criticize or condemn a product, solution or service that is below their ever-expanding expectations regarding performance and quality of experience. To ensure that these expectations regarding QoE are met, it is incumbent upon the operators and equipment suppliers to engage in detailed, repeatable, reliable performance testing to stress multiple layers of the network and devices under the most real/lifelike conditions as possible.
Want to read more on LTE testing? Download RCR Wireless News’ recent special report on LTE Field Testing.
