The next generation of wireless technologies will require creative approaches to spectrum. Each radio upgrade brings diminishing leaps in terms of mobile performance and so it becomes more important to be able to harness more spectrum, and use what is already available more efficiently.
That will involve many techniques in 4G expansion and 5G, some of them being developed in the 3GPP standards process, some emerging from individual vendors. The table summarizes the main options which will be available to MNOs in the coming years.
Some of these solutions, including full duplex and advanced cognitive radio, are still in their infancy, but other emerging techniques are immediately usable and, initially at least focused on existing and even legacy technologies.
Huawei’s CloudAir is one example, which Wireless Watch has been monitoring with particular interest since it first appeared in 2016. This works alongside the vendor’s Cloud-RAN, Cloud-Edge and other virtualized offerings. It manages spectrum from a cloud platform and supports dynamic allocation of spectrum bandwidth across multiple bands.
With CloudAIR, different RATs can share the same spectrum, and spectrum resources can be allocated automatically where traffic requires. This maximizes spectral efficiency and helps get new RATs online more quickly, while also preventing legacy terminals from occupying spectrum for long periods of time.
Now India’s Bharti Airtel has become the first MNO to deploy three radio standards – GSM, UMTS and LTE – within the same band, using CloudAIR to support all three technologies dynamically in 8.8 MHz of bandwidth in the 900 MHz band.
Indian operators are particularly sensitive to issues of spectrum efficiency, since – despite recent consolidation and auctions – they still have insufficient capacity in many markets to support rapidly rising mobile usage and improve quality of service. By using its 900 MHz spectrum to support all its three networks, simultaneously, Airtel is maximizing the usage and value of its frequencies, increasing spectral efficiency, addressable capacity and boosting user experience.
“CloudAIR gives us the ability to deploy LTE within the same 900 MHz frequency alongside GSM and UMTS,” Airtel CTO Abhay Savargaonkar said. “This improves our LTE coverage significantly, which means our customers enjoy superior data experience and HD voice quality even in indoor locations.”
“We launched the CloudAIR solution to help reshape the air interface,” said Edward Deng, Huawei’s president of wireless solutions, when the offering was first launched. “Our focus is on improving the efficiency of the air interface, enabling operators to deploy services more flexibly and, of course, enhancing user experience. CloudAIR is designed to enable more efficient sharing of air interface resources like spectrum, power, and channels.”
Also being added to the platform are support for sharing power, RANs, spectrum bandwidth and cell sites between operators, laying the foundations for multi-operator networks. Like spectrum flexibility and virtualized RAN, multi-operator support may be optional in 4G, but will be essential to many aspects of the 5G environment, especially ultra-dense networks – though the barriers in its way are not just about technology, but about operator resistance and regulatory roadblocks.
Another interesting aspect of CloudAIR is support for channel sharing driven by artificial intelligence (AI), a technique in which operators are showing increasing interest as a way to automate the management of their resources in a highly flexible way. AI-based scheduling enables received signals to be recognized as available multipath resources to enable better site selection.
Huawei says CloudAIR is deployed in about 30 commercial networks, but this is the first one to support three radios. Most are using the technology across 2G and 3G, in order to balance data and legacy services in small amounts of spectrum. In future, however, the techniques which CloudAIR pioneers will clearly be applicable to 5G, and will have far greater potential to improve the MNOs’ business case there.
CloudAIR aims to accelerate the shift from localized, discrete deployments to an end-to-end strategy encompassing most of the network, since Huawei claims it will significantly improve the cost justification for a cloud core and RAN, as well as allowing operators to make far better use of their most precious asset, spectrum. Like its stablemates, it is designed for implementation with LTE/3G/2G networks, the catalyst often being a move to LTE-Advanced and a broader virtualization roadmap.
But it also clearly prepares the network architecture for future migration to the 5G radio, given that the most important aspects of 5G are expected to be its software-driven nature, its programmability and its extreme flexibility, including network slicing. These are changes to the network, but also to organization and culture, which the operators need to start making in their current systems, rather than having to go through a big bang reinvention of their entire architecture when they decide to adopt the 5G radio – which may not be until the mid-2020s for many.
The new addition to Huawei’s portfolio is perhaps the one which is most clearly geared up for 5G. Deng said: “Air interface is the most valuable resource that operators have. And if this most valuable resource doesn’t support efficient, on-demand, and agile network deployment, then a mobile network isn’t truly cloud-based.”
The main justification for 5G migration, particularly an early-stage one, will be its ability to support many services, enterprises and service providers, each of them with different requirements in terms of network behavior (data rates, quality of service, security, bandwidth, signalling load and so on). The ability to virtualize the network from RAN to core to backhaul will be critical to the business model, to deliver virtual ‘slices’ for each service, on-demand and optimized for its particular requirements – whether those are sub-ms latency of multi-Gbps speeds, or even both.
CloudAIR takes a step towards making this high concept into practical reality, because it supports flexible sharing of spectrum, power and radio channels.
Deng argues that MNOs will have to adopt a cloud-based architecture if they want to move beyond their current (and struggling) mobile data model, and to adopt 5G in a commercially meaningful way. He said that, to support service diversity – which is emerging on mobile networks for the first time as everything gets connected, not just handsets – “a modern network needs efficient resource utilization, on-demand module deployment, and agile service provisioning if it hopes to achieve long term development. And building a cloud-based network is the only way to make that happen.”
CloudEdge provided the first step in this direction, supporting multiple radio access technologies (RATs) and looking ahead to slicing networks in order to deliver “tailored scenario-based solutions”, as Huawei called them.
CloudRAN became commercially available last year. It has passed business verification tests in China, Italy, South Korea and Japan and has been in trials with several operators, sometimes in pre-commercial form, and heavily tailored for individual carriers’ architectures.