Bringing 5G and optics together through the MOPA initiative

With everything in our information society happing so fast with new technologies, capacities and application impacting every aspect of our lives, one can’t help sometimes to reflect a bit on the history of communications. Looking specially at 5G and optics, it is interesting to note that both these technologies were first researched as far back as the 1960s and 1970s, reaching wider commercial use the following decade. But what I think is even more interesting is that these two technologies would not impact or intersect with each other in a significant way until the present era of 5G.

Spectral efficiencies and spectrum allocations of previous mobile generations (2G, 3G and even 4G LTE) did not crank out more than a few hundred megabits per second. These are of course very useful bitrates for mobile broadband subscribers, and the many other uses of cellular technologies, but they do not really challenge the capabilities of optical technologies, which are instead driven by data centers, residential broadband, and the aggregate dataflows of transport network.

With 5G, that picture is changing. 5G radios and basebands are equipped with 25 gigabits-per-second optical pluggable ports to handle the much higher data rates possible with broader 5G spectrum allocations.

This, together with the requirements on 5G optics to be very reliable, the cellular networks need to work for first responders and other life critical services, handle high and low temperatures of outdoor environments around the world, and be very cost-effective, means that 5G optics suddenly require the full attention of mobile network operators, systems vendors and optics vendors.

What is the MOPA initiative and why are we doing this?

Now that optics is one of the critical technologies for 5G, it is important that the optics needed for the 5G network rollouts are available at the right time and at the right cost. In order to secure that, some things need to come in place:

1. The industry needs to have a common and shared view of what are the right optical pluggable variants. What data rates? What distances? What wavelengths? And so on. Compared to the relatively structured and aligned view on the needs and evolution of mobile networks coming from 3GPP, the optical space is much more diverse with many different architectures and solutions proposed.
2. In order for that to happen the industry needs have a common and shared view what the most important deployment cases are.
3. To achieve this common and shared view, the leading systems and optical pluggable vendors need to jointly work out and document these deployment cases and make this work publicly available.

A 25 gigabit-per-second optical pluggable, used in 5G radios and basebands

The MOPA initiative is doing exactly this: 23 experts from Ericsson and Nokia – two leading radio access network (RAN) vendors and three leading optical pluggables vendors, II-VI, Lumentum and Sumitomo Electric, have produced a joint technical paper describing for the first time the most important optical solution deployment cases for 5G transport networks.

The Ericsson team of myself and my colleagues Antonio Tartaglia, Fabio Cavaliere and David Sinicrope who are among the best collection of people I have ever worked with, has been instrumental in driving the production of this landmark work.

Here are some benefits of the MOPA initiative:

• All industry players (mobile network operators, systems vendors, and optical pluggable vendors) can gain from this common and shared view to make it easier, and with lower risk, to estimate and plan the evolution of networks and products.
• R&D work can be done faster and more effectively with reduced risk.
• Better ecosystems with more stable and sustainable supply chains can be produced.

Without the MOPA initiative, mobile network operators face greater risks of using solutions and pluggables that are not optimized from a total cost of ownership (TCO) and future-outlook perspective.

What does the MOPA technical paper include?

The background to, and evolution of, 5G is one of our industry’s biggest success stories. As such, it is worth recounting it from an optical transport perspective. The MOPA technical paper does exactly this, starting with the background, evolution, and future broad strokes of needs.

General requirements are then established before the optical solutions and the pluggables are described in the context of optical blueprints, where each describe one of the most relevant deployment cases.

Each optical blueprint comes with an illustration and table of relevant characteristics. The technical paper contains 19 blueprints, divided into the popular RAN deployment cases of distributed RAN (DRAN), centralized (CRAN) and virtualized RAN (VRAN). For each, the pluggables for the important bitrates and interfaces of low-layer split (LLS), high-layer split (HLS), and backhaul are included. The optical blueprints use the most suitable technology for that deployment: gray optics, dense wavelength division multiplexed (DWDM), or packet aggregation. This is unlike many other standards and technical papers that only focus on one interface (e.g. LLS, often described imprecisely as fronthaul) and one technology (such as DWDM). Now, for the first time, we have a combined collection of the most important solutions in one technical paper.

For future needs identified, with technologies not yet available commercially, and technical solutions not yet agreed to be mainstream, MOPA has additional chapters as a guide to the industry.

MOPA general requirements

The multilateral MOPA team felt that it was important, and spent a lot of time, to specifically establish the general requirements on optical pluggables and solutions for 5G. Again, for the first time.

A mast with many radios and antennas, arranged with three radios for each band.

The main areas of requirements are as follows:

• Loss budget of fiber, connectors and components: Fiber plants for mobile transport are often newer and better than the oldest fibers plants an operator have. But it is also not as controlled and good as an indoor fiber network. Therefore, the MOPA team felt that it was worthwhile to define a table of the channel insertion loss vs distance for the fiber, connectors and wavelength components that are used in mobile transport. This table is a balanced compromise between excessive margins, which become costly, and sufficient margins to assume good quality in real networks.
• Lifespan: Since the radios may need to be in service for a long time, and it is costly to have field personnel replace optical pluggables in the radios up in the masts, the pluggables need to have a lifespan of 15 years with low failure rates.
• Tunable and automatic self-tuning DWDM pluggables: For DWDM networking, it is impractical to have inventory of 48 or 96 different pluggables. Thus, tunable lasers are preferable even when coming at a cost premium. Moreover, pluggables should be self-tuning to reduce manual configuration.

What’s next?

The MOPA technical paper is launched June 8 after a very intense but rewarding work in the MOPA team. Being publicly available on the Ericsson web pages, anyone interested in the areas of optics and 5G transport is highly encouraged to take a look at the paper!

MOPA is anticipated to become a significant element of future 5G optical transport rollouts and the start of new, improved dialog and progress in the industry.

An easy goal shot for 5G optics?

Read our new MOPA paper

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