Troubleshooting mobile handset performance at network level

October 2020

Stuart Waine of Spry Fox Networks explains why a strong mobile signal is futile if end user devices are unable to deliver satisfactory Quality of Service (QoS).

In a world driven by digitization, reliable mobile coverage for high speed voice and data services is taken for granted regardless of location and its usage is no longer limited to conventional communications. Ubiquitous mobile connectivity is one of the enabling technologies underpinning process automation and IoT. With the much-anticipated rollout of 5G and the benefits it is expected to deliver, combined with exponential growth of self-help applications to reduce in-person contact subsequent to Covid-19, demand for seamless mobile connectivity and resilient ICT infrastructures, particularly inside buildings, have never been greater.

Causes of poor-quality signals

Irrespective of OEM, or model number, a mobile handset is only as good as quality and strength of the RF signal(s) it is able to receive. A range of factors will impact signal quality including terrain, topography, physical location, electromagnetic spectrum and adverse weather conditions; these factors can degrade signal strength and accentuate signal reflection and noise levels, and this ultimately effects usability at device level. Large building structures are particularly detrimental to signal strength and quality because their complex layouts and glass/metal/concrete facades serve as the ultimate mobile signal blockers. This is particularly true for the higher 4G and 5G frequency bands needed for super-fast Internet access. Another factor often completely overlooked is the device itself and the positioning of its RF antenna and processor. Optimising a smartphone signal at design level should theoretically give you the highest signal quality, but this isn’t necessarily the case as the notorious iPhone 4 reception problem demonstrated. This phone’s unique design feature, which comprised an external antenna and bezel rather than embedded ones, significantly weakened signal strength levels if the handset was not held in a certain way.

The truth about bars and masts

Performance issues are also caused by devices not dynamically connecting to the best available signal source, a problem that is exacerbated inside any building infrastructure. Equally, signal reception levels (indicated by number of bars displayed on the screen) are totally arbitrary due to discrepancies between the different mobile operators and devices. The situation is compounded by the requirement to accurately correlate data generated by the network(s) and the device in real world scenarios with constantly changing frequency levels, and not just in lab simulations. Most handsets have been designed to dynamically connect to mobile phone mast propagating the strongest RF signal and in line with parameters stipulated by the different mobile network operators (MNOs). These parameters can vary hugely depending on factors such as MNO business models, network maintenance or frequency changes. If there are capacity challenges with a tower in closest proximity to the phone, for example, a mobile device is usually configured to dynamically seek an alternative signal source. However, the majority of devices do not automatically revert back to the closest signal source once the capacity issues has been resolved, thus causing ongoing performance problems.

Poor quality mobile signals are no longer limited to usage either. In a world driven by autonomation and IoT, ubiquitous RF coverage is the driving force behind M2M applications and data-driven services. Industries across the board are using 4G to power smart technologies such as access control, smart building applications, delivery drones and industrial robots to name but a few. Reliable mobile connectivity is not essential to performance and logistics, it is fundamental to safety critical communications.

Overcoming connectivity challenges

With more companies switching to mobile only strategies for performance and operational reasons they are 100% reliant on seamless mobile connectivity, so signal quality and strength must be constantly maintained. Accurately measuring this requires special tools, many of which have not been designed for 24x7 usage in a field environment. Communications infrastructures must be rigorously tested at network and device level and report back the various signal and performance issues so they can be dynamically addressed.

Wi-Fi

An obvious solution is to implement an ultra-high-speed Wi-Fi network, and while this goes a long way to providing the levels of coverage needed, it does not resolve the connectivity challenge in its entirety. The entry point to many Wi-Fi systems is via copper cabling which is highly variable in terms of connection speed due to issues such as cable distance, and the quality of the copper and insulation. This often adversely impacts upload and download speeds. Additionally, in-building Wi-Fi is propagated via a series of access points, and the QoS for all connected devices is dependent on their proximity to those access points. System security on Wi-Fi networks can be easily compromised using freely available technologies putting businesses at risk to cybercrime. Although the latest Wi-Fi security standard (WPA3) overcomes many of these shortfalls, there is no synergy between different device protocols and even then, the different access points still present areas of weakness.

Mobile signal amplifying systems

Another possible solution is to make use of signal amplifying technologies such as mobile repeaters, small cells or femtocells. Although these technologies are capable of improving the quality of the different signals they’re broadcasting, they cannot guarantee signal quality at device level due to size limitations, supported RF power and backhaul challenges. As a result, many organisations are still reliant on round the clock network monitoring which is not only resource-intensive, but with coverage issues not being detected in advance, troubleshooting initiatives are reactive rather than proactive.

Safety critical communications systems

The need for seamless connectivity and QoS are taken to the next level if an installation is being used to facilitate safety critical communications, as is often the case in basement locations. With the UK set to migrate its existing public safety communications network from the Airwave network to the new 4G-based Emergency Services Network (ESN), all commercial properties will be obliged to review their in-building mobile coverage strategies because without a reliable 4G signal, first responders and blue light services will not be able to effectively co-ordinate an emergency situation. Not only does this put lives at risk, it poses the question of who would be culpable in the event of a public enquiry!

The future of 5G and digital automation, as well as the success of the UK’s new ESN are all dependent on seamless in-building mobile coverage and QoS assurance. Futuristic IoT-driven applications still need to align with existing protocols and methods, and dynamic network monitoring to assure the fastidious performance of all connected devices will be instrumental in optimising cost-efficiency, safety and security as well as ensuring coverage levels are maintained for both M2M and person to person applications. 

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