Deep fibre - Fibre for 5G infrastructure connectivity

The future is 5G and there is no 5G without fibre! In Europe, 70% of towers are connected by microwave links, as data goes from 6GB to 98GB/mth/user by 2025 we need fibre to every tower. 

Deep Fibre for 5G 

The future is 5G and there is no 5G without fibre! In Europe, 70% of towers are connected by microwave links, for both 4G Advanced Pro and 5G this will need to change as data consumption goes from 6GB/mth/user to 98GB/mth/user by 2025 with peaks of 300GB+, we will need fibre backhaul to every tower.

Many mobile networks today are centralised, with say 3 to 6 Data Centres (DCs) and backhaul from these DCs going out via fibre, ethernet and microwave links to the base stations. The DCs will all sit on dual fibre rings. Going forward many operators will look to push these DCs closer to the edge, eg Three UK has 21 DCs, with the dual backbone fibre rings not only connecting them all together but also each DC has its own fibre rings to connect to the nearby towers, roof tops, etc. In the UK, the ubiquitous Monopole will today be connected via leased line or ethernet or microwave. The sites will have typically 300Mbps to 600Mbps connectivity.

4G Adv Pro build out will continue across Europe for the next 4 to 5 years, and that will bring a 1Gbps connectivity requirement as a minimum for each and every tower.

For initial 5G (Non-Standalone) launches the 5G radio is added to a 4G core, so microwave will still be dominant with initial central city sites getting 1Gbps or possibly 10Gbps backhaul links using both microwave and fibre.

For 5G Standalone (2021/23) most all sites will need to be fibre connected with 10Gbps or at worst 1 to 5Gbps 70/80GHz microwave links. Then mmWave Small Cells could need up to 24 or 40Gbps Dark Fibre connections. Here the gNodeB direct connects to the DC, latency <10ms becomes a key requirement.

The challenge for the industry is that the current rush to build out FTTH/FTTP doesn’t really help, often the network architecture is all wrong (centred on linear street connections, existing ducts at street level and possibly BT or equivalent exchanges) and the technology (GPON/xGPON/Ethernet) doesn’t fit with 10Gbps dark fibre (future 5G minimum).

For 4G/5G in the UK there are over 47,000 physical sites and close to 63,000 base stations each needing 1 to 10Gbps in a star and hub approach back to the DC. These sites are on rooftops (not street level), in brownfield locations (industrial) and of course in fields, beside roads – not in residential streets. These transmission links are expensive; however the future should see local data breakout (5G Standalone User-Control plane split) which will help reduce costs in the near term by putting user traffic straight out to the internet and open up new capabilities, e.g. Edge Computing.

When Small Cells become important to increase capacity in dense urban locations, then fibre will be needed at street edge or front of buildings, here it would be good if local councils assisted by including ducts [for fibre] when they update street lighting (LEDs) or add kerb side EV charging points.

The mobile operators are tackling these challenges with different approaches as they look to expand their legacy 4G transmission networks with new fibre connections and as new high-speed microwave technologies come on stream, eg 143GHz microwave links providing 10Gbps on each connection, with multiple connections per site.

Peter Curnow-Ford from Viatec Associates - Email Peter or follow on Twitter

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