CloudAIR 2.0 unleashes all-spectrum potential

2018.06.06 By Hao Fei

At Mobile World Congress 2018, Huawei's CloudAIR solution won two awards: GSMA’s Best Mobile Technology Breakthrough and CTO’s Choice for Outstanding Mobile Technology. These were in recognition of Huawei's innovations in the field of radio air interfaces, a critical technology for mobile broadband networks. According to one judge, “Cloudification of the RAN is still in its early stages, but the actual benefits in commercial deployment helped to separate CloudAIR 2.0 from other solutions.”

30 commercial deployment cases

Future networks will be deployed on multiple frequency bands, accommodate multiple Radio Access Technologies (RATs), and have greater requirements on power. To address these demands, CloudAIR allocates air interface resources on-demand, including spectrum, channel, and power, according to traffic demands or mobile user location. Mobile operators can then optimize network spectral efficiency, capacity, and user experience.

Huawei introduced CloudAIR at the 7th annual Mobile Broadband Forum (MBBF) in November 2016 and showcased the solution at MWC 2017. The early version of CloudAIR, which included sharing GSM and UMTS spectrum and also GSM and LTE spectrum, has been deployed widely by operators across the world.

Vodafone Turkey and Huawei achieved unparalleled overlap by using 900 MHz for GSM (2G) and LTE (4G) services. Huawei’s solution enabled greater flexibility in the way that blocks of 900 MHz spectrum could carry both 4G and 2G traffic and assign spectrum dynamically between 4G and 2G services based on customer demand. GL spectrum sharing raised average downlink user throughput by 58 percent and uplink user throughput by 44 percent over a standard 5 MHz block of LTE bandwidth.

CloudAIR has been widely commercially deployed across Turkey. India’s Bharti Airtel implemented CloudAIR to deploy LTE within the same 900 MHz band as GSM and UMTS, significantly improving LTE coverage and the mobile user experience. Compared with an alternative approach for deploying LTE in a higher frequency such as 1800 MHz, 900 MHz LTE required 30 percent fewer sites to achieve the same coverage and enabled Airtel to increase network traffic by 20 percent.

CloudAIR has proven to be a valuable solution allowing different RATs to share spectrum resources dynamically, instead of using traditional spectrum refarming solutions. The solution has been deployed in over 30 commercial networks, including in Thailand, Turkey, Indonesia, Uganda, and Bulgaria. It has enabled operators to improve mobile network quality and user experience and save network investment.

How it works

CloudAIR 2.0 features new technologies that dramatically increase spectrum sharing and support LTE and 5G NR on the same spectrum.

Deeper spectrum sharing for dynamic allocation and adjusting spectrum resources: To deploy new radio technologies such as 5G or LTE, mobile operators need to release blocks of spectrum from legacy radio technologies such as UMTS and GSM. However, releasing blocks of spectrum can reduce capacity and worsen user experience. But, if operators wait for traffic to decrease on existing radio technologies to unlock spectrum, they risk hindering network development, which will in turn stifle new growth opportunities.

Another approach is to acquire entirely new spectrum, but this involves buying more spectrum at hugely expensive auctions. For example, in 2015 Bharti Airtel paid US$236.3 million for a band 1 (2.1 GHz) 5 MHz spectrum covering 110 million people. In the same year in Thailand, True paid US$2.16 billion for a 10 MHz paired spectrum in 900 MHz.

The spectrum sharing capabilities of CloudAIR 2.0 enable the deployment of different RATs in the same spectrum. This solution can dynamically allocate and adjust spectrum resources according to changes in mobile traffic and avoid legacy RATs taking up prime spectrum, improving spectrum efficiency.

Doubling the spectrum sharing ratio enhances network performance: Compared with Huawei’s first release, CloudAIR 2.0 doubles the spectrum sharing ratio, which greatly improves network performance.

Without CloudAIR 2.0, an operator can typically deploy three GSM carriers and LTE 5 MHz within 10 MHz of spectrum. With CloudAIR 2.0, the operator can deploy the same three GSM carriers and LTE 10 MHz simultaneously with a 4.4 MHz sharing spectrum block between both technologies. Compared with a 5 MHz LTE carrier, a 10 MHz LTE carrier with sharing spectrum offers a network capacity gain of around 90 percent, saving 4.4 MHz of spectrum for the operator.

Full coverage for all services on a low frequency: Spectrum sharing is not limited to two coexisting radio technologies. CloudAIR 2.0 supports spectrum sharing with multiple RATs in the same frequency. This solution is ideal for operators looking to extend LTE and cellular IoT coverage on a low frequency.

Cellular IoT represents important growth opportunities for mobile operators looking to expand their business beyond traditional voice and data services. At the same time, VoLTE is a next-generation voice solution that offers better call quality than 3G or 2G. As users migrate to the new service, the spectrum used for 2G can potentially be repurposed to increase the capacity of LTE networks.

However, most operators have limited spectrum bandwidth in low frequencies, such as 900 MHz, which is currently used by legacy technology such as GSM and UMTS. Therefore, operators cannot deploy VoLTE and cellular IoT on a low frequency until the spectrum is released or they acquire more dedicated spectrum.

With CloudAIR 2.0, both VoLTE and cellular IoT can be deployed on limited bandwidth coexisting with GSM and UMTS, which allows a low frequency to become a fundamental network layer to support all services. A typical lower frequency coverage layer requires 30 percent fewer sites than a higher frequency, saving operators a significant amount of investment.

Spectrum sharing for full network coverage by LTE and 5G: The deployment of a nationwide 5G NR network with dedicated infrastructure and frequency is a costly investment, both in infrastructure and resources. Furthermore, low 5G mobile penetration in the early phases will result in light network loads that lengthen the ROI period.

C-Band, a globally harmonized frequency allocation for communications satellites operating between 3.4 and 4.2 GHz, will be the key spectrum for 5G. However, its coverage radius is less than the popular LTE frequency 1.8 GHz.

In December 2017, the first 3GPP 5G NR standard was finalized. According to the 3GPP standard, many 5G NR frequencies have been defined which are the same frequencies as for LTE, making it possible for operators to deploy LTE and 5G NR in the same frequency.

With the joint efforts of leading operators and ecosystem partners, LTE and 5G NR spectrum-sharing has already been accepted in 3GPP, and will be supported in 3GPP R15. Both LTE and 5G use Orthogonal Frequency Division Multiplexing (OFDM) or a variant scheme that defines frequency and time-domain resource blocks.

Therefore, LTE and NR spectrum sharing allows for the flexible sharing of more frequency and time-domain resource blocks, deepening the spectrum sharing ratio and increasing spectrum efficiency. Theoretically, with proper system design, the allocation interval for spectrum resources between 5G NR and LTE can be implemented in a millisecond.

Accelerating 5G deployment and monetize spectrum assets with LTE and 5G spectrum sharing: In many countries, C-Band has already been deployed for LTE. With LTE and 5G NR spectrum sharing, 5G NR can be activated instantly by sharing spectrum dynamically. This will help operators accelerate 5G deployment and shorten TTM for 5G services.

Conversely, operators that have deployed 5G NR using dedicated spectrum need to improve network efficiency, which will have low utilization rates due to lower 5G penetration in the early adoption phase.

With LTE and 5G spectrum sharing, 5G and 4G traffic can share the same frequency, enabling operators to monetize spectrum assets and improve network ROI.

Extend C-Band coverage by decoupling uplink and downlink: C-Band is expected to be one of the most popular frequencies for deploying 5G in many countries, including Japan, South Korea, China, and some European nations. C-Band gives operators abundant spectrum resources; however the shorter coverage in uplink remains a significant issue. If an operator wants to use C-Band to ensure seamless coverage, site requirements could be three to four times higher than for 1.8 GHz.

Using paired spectrum for both downlink and uplink, FDD LTE is a popular approach for radio technology in many countries. Most mobile applications generate more downlink traffic, leaving uplink spectrum in the network idle.

Spectrum sharing combines the advantages of the larger downlink bandwidth of high bands and better uplink coverage of low bands. By multiplexing LTE and 5G NR in an existing LTE uplink frequency and using C-Band’s abundant spectrum resources for 5G NR downlink frequency for uplink and downlink decoupling, operators can significantly extend C-Band coverage.

Huawei’s joint field test showed that C-Band coverage has been extended by around 73 percent, which is equal to 1.8 GHz LTE coverage. Thus operators can reuse the existing 1.8 GHz LTE site resource to deploy C-Band as a seamless network, instead of undertaking costly new site acquisition.

Multi-band power sharing improves network connectivity: Most modern radio networks reduce TCO by using SingleRAN or similar solutions. The multi-carrier and multi-mode features of SingleRAN radio units enable operators to share transmit power in a single radio unit at the same frequency.

In addition to intra-band transmit power sharing, Huawei CloudAIR 2.0 features a new multi-band radio unit that can support inter-band power sharing to improve network connection speed at the cell edge, as well as cell throughput.

Mobile networks evolve toward All Cloud

CloudAIR schedules and utilizes air interface resources, including spectrum, power, and channels, to more efficiently deploy services and improve the mobile user experience.

CloudAIR 2.0 enables spectrum sharing for most of the popular radio technology combinations between GSM, UMTS, LTE, and 5G NR. It can dynamically allocate and adjust spectrum resources according to changes in traffic, helping operators enhance spectrum efficiency.

LTE and 5G NR spectrum sharing can accelerate 5G deployment and shorten 5G service TTM. Unlike deploying 5G NR on a dedicated frequency, operators can monetize spectrum assets. The uplink and downlink decoupling scheme extends C-Band coverage to equal 1.8 GHz, which can slash network investment.

Power sharing and on-demand power allocation across multiple carriers, RATs, and frequency bands represent breakthroughs in OPEX.

As mobile networks evolve towards All Cloud Networks, they will go beyond current boundaries and create unlimited possibilities, becoming the basic architecture for digitalization across all industries and creating new business opportunities in the mobile industry.