Mobile services have changed rapidly over the past decades, bringing significant benefits to our lives. Networks providing these services transmit data using specific radio access technologies (RATs) across specific spectrum blocks, with specific power levels, via specific channels (antenna). Such radio technologies and communication elements are tightly coupled, which inconveniences mobile operators and lowers network efficiency. 
Present Challenges
Extremely high spectrum costs
Spectrum is the most precious asset for mobile operators in the wireless communication era. To deploy new radio technologies such as 5G, mobile operators must remove certain spectrum blocks from LTE, UMTS, GSM and other existing technologies or buy entirely new spectrum. 
The removal of spectrum blocks from existing technologies reduces capacity and degrades user experience.
Waiting for traffic to decrease naturally on existing technologies and releasing more spectrum to accommodate new technologies postpones network deployment, and deprives operators of the opportunity to cultivate high-end mobile users during the market initialization phase.
The cost to operators of buying more spectrum through spectrum auctions is extremely high. In Canada, Rogers paid 3.29 billion USD for 22 paired spectrum blocks, covering 33.36 million people in 2014. In the US, the AWS-3 spectrum auction cost operators 44.9 billion USD in 2015. In India, Airtel paid 236.3 million USD for a band 1 (2.1 GHz) 5 MHz spectrum, covering 110 million people in 2015. In Thailand, True paid 2.16 billion USD for a 10 MHz paired spectrum in 900 MHz in 2015.
Slow deployment of new technologies
When introducing new-generation radio technologies (such as 4G), good network coverage helps operators build a strong brand. This in turn inspires customer loyalty and grows market share.
Unfortunately, it takes most operators 6-7 years to build a network with nation-wide coverage when introducing new technologies. For example, a mobile operator in Germany began deploying LTE in 2011, yet their network is expected to need until 2017 to cover more than 95% of the population. In reality, this operator achieved nation-wide GSM coverage by using 900 MHz several years ago. They cannot however deploy LTE on this frequency as the spectrum is still occupied by GSM.
Static resource allocation for changing traffic volume
GSM and LTE usage peak at different times in most networks due to different patterns in voice and packet traffic. Traditional refarming solutions allocate dedicated and static spectrum blocks regardless of the daily changes to voice and packet traffic volume.  
For example in China, GSM networks bear the brunt of voice traffic,which peaks just before midday. Packet traffic volume peaks in the evening around 8pm.

Degraded user experience in high-population-density areas
In a traditional network, every site has fixed cell coverage and experience is inconsistent across different locations due to radio signal attenuation. Service tends to be strong at the cell center and weak at the cell edge. In denser areas, the network experience at the cell edge may suffer further due to radio interference across cells and a complicated radio environment.
In response to these challenges, Huawei introduced the CloudAIR solution at the 7th annual Mobile Broadband Forum in November 2016. CloudAIR redefines radio communication with the cloud philosophy to create a more efficient network. This solution shares static resource allocation to specific radio technologies to dynamic sharing on demand.
CloudAIR covers 3 technical areas of cloudification: spectrum, power, and channel.
Spectrum cloudification
Refarming technology allocates dedicated spectrum to both existing and new radio technologies. Wide-band communication accounts for most types of new technologies designed to be deployed across a defined bandwidth block. For example, LTE bandwidth is designed to support 3 MHz, 5 MHz, and 10 MHz spectrum blocks. Meanwhile the legacy radio technologies such as GSM is defined with 200 KHz carrier bandwidth. If the spectrum vacated from GSM is not sufficient to cover LTE’s defined bandwidth, the spectrum cannot be fully used by refarming technology.
The voice traffic and packet traffic have different patterns, resulting in different peak times for GSM and LTE networks. The static spectrum allocation scheme used by refarming technology can’t accommodate this variety, leading to low spectrum utilization across the network.
Refarming is widely used across modern networks to deploy multi-RATs in the same frequency band, dividing spectrum blocks into several sub-blocks and assigning every spectrum sub-block to a specific technology. Spectrum cloudification enables multiple RATs to dynamically share the same spectrum in a modern radio network.  
By deploying smart scheduling and interference mitigation, these technologies may now share the whole spectrum block (except frequencies used for broadcasting system information).
Spectrum cloudification is designed for most modern radio technologies, including GSM & UMTS co-deployment and GSM & LTE co-deployment. LTE & 5G co-deployment may also benefit from spectrum cloudification in the near future. 
Save spectrum investment and accelerate network deployment (one-click for full coverage of RATs)
Spectrum cloudification enables spectrum sharing between new and existing technologies and eliminates the need for dedicated spectrum. By leveraging this aspect of CloudAIR, operators are free to deploy new radio technology without waiting for traffic to decrease and vacate the spectrum. Operators also avoid significantly impacting legacy network capacity, degrading user experience, and buying new spectrum at high cost. New technology can now be deployed at lower cost and coverage can be extended nation-wide in a shorter time.
Expedite 5G network deployment
In a future of standardized 5G, spectrum cloudification helps operators deploy 5G more easily by sharing spectrum with other technologies. When they share through spectrum cloudification, both technologies have the same amount of coverage. In other words, operators with nation-wide 800 MHz LTE networks can use spectrum cloudification to ensure equivalent 5G coverage in record time. 
Maximize spectrum efficiency
Spectrum cloudification allocates spectrum to different technologies according to traffic volume. When traffic across the GSM network increases, more spectrum will be allocated. While traffic across the GSM network is low, LTE could use more spectrum to provide higher speeds and a better user experience. This on-demand spectrum allocation scheme significantly enhances spectrum efficiency. 
Smooth Phasing-out of Legacy Network
The number of GSM mobile users in Europe has been in decline for the past 10 years. Owing to the long-tail phenomena however, remaining users still enjoy notable penetration rates. There are also M2M applications that do not require a high-speed data connection, such as point of sale terminal and cargo tracking devices using GSM connections to enjoy wide coverage. Consequently, mobile operators run a GSM network with high costs and low resource efficiency. The GSM network occupies ‘golden spectrum’ such as 900 MHz, which has good propagation properties and abundant site resources. To guarantee good coverage for the GSM user, such limited ‘golden spectrum’ is unavailable to LTE and other new technologies. This makes it difficult for mobile operators to promote ‘golden spectrum’ and extend their LTE coverage. Without ubiquitous coverage, operators need to pay more in marketing costs to persuade customers to use their new radio technology network.
As a result of on-demand spectrum allocation, ‘golden spectrum’ may support both GSM and LTE, assuring strong coverage across both networks and minimizing the side effect of running a GSM network.
Power cloudification
Most modern radio networks reduce their TCO by using SingleRAN solutions. This means that multiple radio technologies are deployed on the same base station hardware. Resource sharing between multiple carriers and multiple radio technologies is essential. The ability to transmit power is critical to determining coverage and connection speed.
Mobile operators could use power cloudification to improve power resource utilization and in turn, network capacity. Different carriers and different radio technologies could share transmitting power in the same physical radio unit. This will make radio technologies transmit more power to improve network connection speed at the cell edge, which will increase cell throughput as well. 
Channel cloudification 
Traditional networks are designed to be network-centric. If users are close to the base station (cell center), they will receive good service. Conversely, users at the cell edge receive degraded service due to weak signals. Moreover, cell edges are also known as overlapping coverage areas in that they are designed to receive signals from adjacent cells for handover purposes. All signals from adjacent cells interfere with and deteriorate the radio signals from the original cell, degrading user experience.
Channel cloudification aims to transform communication between network and mobile users from network- to user-centricity and offer a no-edge experience. Channel cloudification leverages multiple signals received in an overlapping coverage area to improve communication quality as well as multi-user MIMO technologies to increase network capacity. Meanwhile, channel cloudification schedules which base stations serve as active clusters depending on dynamic user location. User experience and network capacity is improved significantly in high-density areas such as stadiums and indoor scenarios.
Spectrum cloudification enables dynamic sharing of the same spectrum by multiple RATs in modern radio networks. Compared with refarming, this changes the way operators deploy new wireless technologies at lower cost, shorter time, and wider coverage. Since spectrum cloudification applies to technologies up to 5G, areas with 4G coverage now enjoy 5G coverage. Thus, 5G coverage is faster and further.
Power cloudification improves resource utilization of transmission power. This improves the capacity of networks shared by different carriers and technologies.
Channel cloudification converts the network to a user-centric model for consistently good experience especially in high-density scenarios.
Huawei cooperates with global partners in promoting the CloudAIR solution. In India and Nigeria, Huawei used CloudAIR to co-deploy GSM and UMTS in the same spectrum block. Similarly, CloudAIR was used to co-deploy GSM and LTE in Turkey and Thailand. Channel cloudification has been deployed in China and Japan to improve network performance in highly populated areas.
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