Testing My App in a 5G Network

Posted by Chris Wellens /

Practical considerations for software developers considering 5G network emulation

5G is the latest technology for cellular mobile communications. Deployment is expected to take place sometime between late 2019 and mid 2020. The benefits of 5G will be available to new, 5G-enabled devices. However, developers who need to know what kinds of hurdles to expect for their applications may be disappointed.

Promise of 5G

Compared to the current 4G with a maximum speed of 100 Mbps (Megabits per second), 5G will offer a maximum speed of 10 Gbps (Gigabits per second). That works out to a 100-fold performance improvement over current technology. In addition, download speeds will improve; a two-hour movie requiring six minutes to download with 4G networks, will download in less than five seconds in a 5G network.

Related to the 5G maximum speed is latency. Latency is expected to dramatically improve in 5G networks providing the potential to enable many latency-sensitive applications.

Achieving these performance improvements requires several different kinds of technologies – including millimeter waves, massive MIMO, full duplex, beamforming, and small cells – More Info

We believe the most interesting questions about 5G for software developers are:

  • What are the experiences with boundary-conditions and how do application developers assure the best possible user experience?

  • What happens under conditions of severe-congestion, such as in emergencies or in high-usage-density situations like Manhattan?

  • Which impairments to network service delivery will my software and/or hardware product(s) need to overcome to avoid product-returns, complaints, and customer alienation?

  • Because 5G will not be deployed all at once, everywhere, users will experience transitions as they move between 5G and legacy technologies. Will those transitions be smooth or abrupt and disconcerting?

Unfortunately, the answers are unknown!
What? Why?

So far, the focus of the 5G testing effort is only the 5G network itself! The testing addresses issues such as: mmWave signal propagation, combinations of walk tests and stationary tests, varying near-line-of-sight (LOS), and signal diffraction.

Currently developers of 5G network components can acquire 5G test beds to perform design validation at the physical level, including transmit signal quality testing, radio signal distribution against time and frequency. Thus, the testing is limited to finding and fixing bugs with basic 5G network functionality, and finding workarounds for problem areas.

But an app developer needs to test in a realistic mixed-technology network, most likely consisting of a mixture of 5G and legacy technologies.

That’s where IWL comes in. For developers who want to see how their product will perform in 5G networks, IWL will add 5G network scenarios to our KMAX network emulators to assist and support app developers in understanding how their app performs under adverse 5G network conditions, ranging from the routine to the extreme.

What’s the difference between 5G-Only Network and 5G Plus Legacy Technology Network?

5G-Only Networks

Current field trials are taking place in dedicated 5G networks, where the entire network is based on 5G and no legacy technologies are included. For example, the Worcester Bosch factory in the UK is combining IoT sensors and 5G for monitoring operations for preventative maintenance. Part of this experiment is to test end-to-end application performance. Source

5G Plus Legacy Technology Network

But the real world is not going to go 100% 5G in one day. Nearly all applications will be deployed in networks containing some of the new 5G devices, but those networks will also contain legacy network equipment, including 3G and 4G technology, Ethernet and other long distance communications (e.g. satellites).

Where are the test sites for the 5G Networks?

Verizon has deployed 5G trial networks in Houston, Sacramento, Los Angeles and Indianapolis. Source

Rhode & Schwartz along with Signals Research Group performed testing on the 5G trial network in Houston. Source

Qualcomm created a 5G Network Capacity and User Experience Simulation Platform in both Frankfurt and San Francisco. This is a first step in broadly understanding aggregate 5G performance in mixed technology networks. Unfortunately, it is not that helpful for the developer who needs to test an app or device against the full range of 5G network conditions ranging from the routine to the extreme. Source

Should I expect any new types of network impairments with 5G?

IWL has reviewed and published the common causes of network impairments (i.e. packet drop, duplication, latency, re-ordering) Read our White Paper

We believe that 5G networks will introduce more packet re-ordering as a side effect of some of the new technologies. Multiple radios (MIMO) will tend to introduce a higher amount of out-of-order delivery of packets, which IWL has observed to be a weakness in many protocol implementations.

Bufferbloat issues may occur as users transition between 5G and legacy network technologies.

Congestion may eventually become a problem with 5G as it becomes a victim of its own success.

The effects of congestion in real-world conditions can’t be measured until 5G technologies are deployed in real networks used by real people using real applications; and even then, new uses will inevitably be introduced, which will stress the new equipment in new ways. However, congestion can be created readily in lab testing so you needn’t wait to find out.


Networks introduce delay, delay-variation, corrupted packets, re-ordering, and duplication. That’s been true since the early days of networking; it did not change when newer technologies were introduced, although the specifics did.

Fortunately, with IWL’s KMAX network emulator, you can very precisely emulate a full range of adverse network conditions to learn where your app or device hits its limits. Then, you can build into your signaling protocols ways to measure ambient conditions, so when your customer tries to use your app or device in a 5G network with a problem, your app or device responds appropriately.

The individual components of 5G networks are new technology but they are not creating entirely new classes of impairments. Stay tuned!

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