Backhaul is considered to be in the top three challenges in deploying RAN. With the traditional approach, bringing backhaul to a site takes a long time and requires a substantial upfront investment because in order to deliver the highest speed possible, Service Providers need very expensive backhaul fiber. Backhaul technology requirements should focus firstly on the flexibility of using different types of backhaul – whatever is available at the potential deployment site, secondly, be easily configurable for mass deployments of small cells, and thirdly, be resilient to any type of failures. These three requirements of backhaul flexibility, automation and resilience were taken into consideration when Parallel Wireless developed their backhaul solution.

The backhaul solution that Parallel Wireless has introduced to the market consists of two components. The first one is a base station (Converged Wireless System or CWS) that has access and backhaul in the same form factor. Secure backhaul options on CWS include: Ethernet, licensed and unlicensed nLOS/LOS backhaul mesh, LTE, and satellite. This backhaul flexibility allows operators to use any type of backhaul (including wireless mesh) to route the traffic from CWS site which simplifies site acquisition process and any associated cost.

The second solution piece is a 100% 3GPP compliant RAN orchestrator, HetNet Gateway (HNG). RAN traffic gets aggregated and optimized on HNG. One of the virtualized functions on HNG is real-time SON which makes backhaul self-configurable, self-optimizing, and self-healing. SON on HNG re-balances loads based on the information received from nodes resulting in optimal backhaul capacity. SON also re-routes packets in case of a link failure.

The nodes could connect to each other and the Packet Core via a mesh backhaul – removing the need to lay out expensive fiber. The nodes can also daisy chain this mesh network even further, bringing low cost wireless broadband to hard to reach areas without any additional expenditures.

The mesh is “multi-point to multi-point” link, with no server or client nodes. Each node talks to its neighbors on a different mesh channel. This support for two independent wireless meshes in the same form factor (CWS) allows the nodes to operate on multiple frequencies and to transmit and receive packets independently.

The mesh is also multi-homed where any egress (wired or LTE) on a given node is available to the full mesh cluster. Also, the CWS can provide Ethernet backhaul to external devices as well e.g. external access points, traffic cameras, etc.

The access and wireless mesh frequencies are pluggable modules on CWS, which could be customized to suit SP’s frequency bands and allow in-band backhaul or “donor” backhaul unit deployment scenarios.

In this case, the CWS is configured to aggregate wireless mesh links so that node itself can have either a wired backhaul or use LTE as backhaul to connect to the network. It provides backhaul connection for other nodes with no impact on existing macros.

All backhaul transport options employ advanced authentication and security features. The communication between the CWS’ and HNG happens over a secure tunnel.

Real World Application

On December 2nd, EE has announced that it would connect 1,500 rural communities in the UK to its 4G network by the end of 2017 using Parallel Wireless micro network technology. This technology makes it easier and more economical to reach isolated locations by eliminating the need for cables to provide backhaul as CWS nodes use backhaul mesh and can form self-configuring and self-organizing mesh clusters.

This flexible backhaul technology is the ideal technology for maximizing the value of existing infrastructure for operators worldwide. Currently, fiber roll-out is very expensive and therefore roll-outs are not happening on a large scale in the access network which especially hinders small cell deployments in hard to reach areas. Parallel Wireless backhaul capabilities (including mesh and in-band backhaul) bridge this gap by providing flexible, scalable, optimized and resilient backhaul solutions that helps bring reliable coverage cost-effectively and on an accelerated timeline.

Parallel Wireless backhaul capabilities can eliminate backhaul bottleneck as CWS can actually create more backhaul. In traditional solutions you have to work with what you got on the backhaul side. As CWS has flexible backhaul including multi-point-to-multi-point mesh, each base station can add up to 450 mbps of “free” backhaul in backhaul challenged environments. The reason it is free is because we will use unlicensed or licensed spectrum that is not being used for access, essentially creating free capacity – based on policies and priorities, traffic can be offloaded to that spectrum. Traditionally, fiber capacity (or Ethernet capacity) has to be shared between nodes taking backhaul from a fiber hub. So, if a cluster had four nodes, the capacity of 150 at the hub will have to be split four ways, giving less than 40 mbps each. It is even worse with macros as each sector will take its share. HetNet Gateway on the backend helps with this spectrum aggregation and dynamic routing in the case of any node failure.

CWS can be also augmented to an existing macro deployment to provide “free” backhaul – when CWS only provides backhaul as an overlay to existing macros. In this mode, CWS mesh will be integrated as an overlay into an existing deployment providing only “free” backhaul over unlicensed spectrum – adding more capacity and resilience. SDN-enabled mesh routing can enable resilience against fiber cuts or other failure scenarios. Every so often we read how fiber cuts caused a network to go down; in this scenario, CWS will provide alternative backhaul.

HetNet Gateway also includes a virtualized multi-technology (3G, 4G, and Wi-Fi) C-RAN functionality. By taking advantage of Moore’s Law for baseband chips, this multi-technology C-RAN allows the use of low-cost System on Chip (SoC). This enables our solution to keep BBU functionality on site instead of it being centrally pooled. This permits operators to take advantage of any type of backhaul (Ethernet, fiber, wireless, etc.) without relying on latency-laden and expensive fronthaul.