SoftBank Japan - rapid small cell deployment in the urban jungleUrban small cells deployed at street level are the next logical step to meet growing data

traffic demand in city centres. Practical solutions need to be quick and easy to install,

adapt seamlessly with tactical evolution and be resilient during outages. SoftBank

installed CCS Metnet self-organising microwave backhaul in the challenging metropolis

of Tokyo, delivering valuable insight into the behaviour of 5G microwave.

The world’s only self-organising microwave backhaul

Enabling 5G

Ultimate flexibility

Planning deployment of urban small cells involves trade-offs between

three key capabilities – backhaul, power and site availability.

Network Topology

Planning deployment of urban small cells involves

trade-offs between three key capabilities – backhaul,

power and site availability. Seven nodes were

installed on existing telegraph poles, with two directly

connected by Gigabit fibre backhaul. The simplest

links were direct line-of-sight along the street, which

coped with reflections from buildings on both sides.

The most remote node had three wireless links

(hops) to reach fibre backhaul. The topology of the

deployment shown below is a live screenshot from

the Management System.

The site preferred by RF planners may not have

electrical power; fibre backhaul may be unavailable

and/or have long lead times to install; some sites

may be much more costly or inaccessible than

others. Flexibility is critical for success.

In the SoftBank implementation, CCS Metnet

simplified the planner’s dilemma by providing high

capacity, highly resilient wireless backhaul which

was able to be quickly deployed in the rapidly

changing environment of Tokyo.

Operating in the 26GHz band that is normally

constrained to Line-of-Sight, this live trials in

downtown Tokyo has proven NLoS (Non-Line-of-

Sight) as part of the mix.

Live screenshot of the deployment topology taken from the Management System.

No skilled tuning or calibration was required for these links – Metnet

automatically senses, filters and adapts to optimise performance and minimise

interference. This is a continuous on-going process, adapting to environmental

changes such as traffic movement, weather and foliage growth.

Rapid installation

All nodes use identical hardware with a single radio per

location. Single RF channel operation does not require any

RF planning, speeding and simplifying installation.

The node shown on the right is a typical street alley

deployment with its neighbour node further along the

canyon.

More unusual were NLoS (Non-Line-of-Sight) links

such as one shown below, where Metnet resolved and

adapted to multi-path reflections from nearby buildings.

The 270 degree wide angle 16 antenna array built into

each Metnet node captures a wide range of signals for

extensive processing and filtering. This is much easier

and more flexible than Point-to-Point radio links which

require alignment, where instead Metnet nodes with their

270degree antenna array automatically detect all possible

LoS and NLoS links and select them accordingly.

Metnet nodes installed on the streets of Tokyo (see purple circles)

Our customer’s experience with Metnet

Dense environments such as this are likely to have small cells spaced closer than 50 meters apart. One link was

32 metres measured as a direct path, with NLoS reflected signals travelling 49 metres. The adjacent nodes had 37

different possible RF links with varying attenuation levels, for which the best options are automatically calculated and

continuously reviewed. This demonstrated the high degree of multipath reflection that occurs in a typical street level

urban canyon. All potential Metnet links are shown in the diagram below.

This link achieved an average signal-to-noise ratio/

modulation of 12dB, supporting backhaul data

throughput of 135Mbps. The link achieved 100%

availability throughout the trial period. Round trip

latency ranged from 0.5ms (1 hop) to 0.88ms (3 hops).

The latest dual channel Metnet radios are capable of

delivering 1.2Gbps using 256QAM in a typical 112MHz

single channel pair.

Operating in a single channel pair without the need to

radio plan, the SON algorithm select the best possible

links and topology, and runs a dynamic spatial TDMA

schedule which dictates exactly which node and

antenna pair can transmit and receive so as not to cause

interference in the cluster. This is made possible by

the thousands of measurements which are taken every

second to determine the real time state of the mesh.

This cognitive approach to microwave networking

Automatic problem-solving

provides a robust and flexible platform in the most

challenging or urban environments.

Metnet addresses many of the issues of urban small

cell deployment, simplifying, adapting and ensuring

resilient high capacity backhaul can become available

to all.

A live deployment in downtown Tokyo is the

ultimate challenge for a small cell backhaul system.

Our engineering team was impressed with Metnet’s

unique MPtMP mesh architecture and approach, and

we wanted to test how this self-organising, self-

optimising, and self-healing microwave solution

performed in a dense urban area.

We designed the trial principally to assess Metnet’s

automatic support for NLOS, and its ability to cope

with multiple RF paths in a multipath propagation

environment – all while delivering optimal performance

and quality of service. Metnet’s capabilities fulfilled our

expectations. The trial has provided a valuable insight

into the behaviour of microwave and mmWave systems in

future 5G bands, and the results of our trial demonstrate

that Metnet can be well positioned to support these fifth

generation networks.”

Tomohiko Furutani

SoftBank Corp. Technology Strategy Office2

Speak to our team todayIf you’d like more information on this subject or CCS products,

please don’t hesitate to contact our team.

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