Demystifying Private Cellular for the Enterprise

New private cellular spectrum, technology, and products now enable enterprises to own and operate their own private LTE and 5G networks. This has sparked widespread interest in the basic differences between conventional enterprise wireless with Wi-Fi and the new enterprise cellular wireless with LTE, 5G, and Citizens Broadband Radio Service (CBRS).

As enterprises continue to deploy Wi-Fi while embracing new private cellular wireless, getting a grip on some of the key technical differences between these two technologies is a first critical step to maximizing the investment of both.  Here are some differentiators and features to consider.

Ecosystem: When it comes to client support, Wi-Fi clearly has an advantage.  But because CBRS is simply another 3GPP band that can be supported by the LTE and 5G modem chipset, support for this band is quickly becoming commonplace.  

Coverage: Due to range limitations and interference concerns surrounding Wi-Fi, determining the best coverage models for any environment has become a costly, cumbersome, and time-consuming task. CBRS alleviates most of this pain, allowing much higher power limits to be used for wireless transmissions.

A single outdoor cellular base station, or AP, has a maximum power limit of up to 50 Watts EIRP to provide coverage up to a mile or more. Indoors, a single CBRS cellular AP at 1 Watt EIRP can cover 10K-30K square feet or more of space due to underlying LTE or 5G technology with consistent performance. This compares to about 4 to 10 Wi-Fi APs to cover the same indoor area. Outdoors the coverage models are even more dramatic, often a 10 to 1 ratio.

Interference: Each Wi-Fi AP or device transmits packets over the air whenever it gets an opportunity to grab the channel and all other APs and devices in the vicinity that can “hear” and decode the preamble back off. While this has worked well for basic Internet access, as more sophisticated applications with strict latency and throughput performance requirements come online, Wi-Fi struggles to maintain the guaranteed QoS. Wi-Fi 6 introduces some enhancements such as OFDMA to help improve the performance, but each AP still needs to compete for access to the channel.  

LTE and 5G don’t work this way.

All wireless transmissions are completely coordinated and scheduled within the network. In a private enterprise network deployment, co-channel interference is managed through this advanced mechanism with APs scheduling transmissions of data for both the uplink and downlink.

Each client device continuously reports the channel quality to the serving AP on the control channels, and each AP schedules downlink and uplink packets using the required network resources to ensure deterministic performance and greater overall network throughput per given amount of spectrum.

Capacity: As more devices come online, it becomes harder to densify Wi-Fi networks because each packet transmission results in silencing others nearby. Usually, the solution is to allocate different spectrum channels for each AP. But this means less spectrum per AP hence less capacity as a network.  

In LTE and 5G, when APs transmit at the same time, they don't back off. Clients can also transmit simultaneously. The transmissions from the other APs or clients on the same channel effectively raises the noise floor. This allows the network to precisely control the desired signal to noise ratio (SNR) for each link achieving better spectral efficiency than Wi-Fi.

In most cases, enterprises should realistically have access to 100 MHz or more spectrum in the CBRS band. While this seems like quite a bit less than Wi-Fi, efficient usage of the spectrum enables high network capacity. For example, a typical mobile network operator (MNO) uses only 100 to 150 MHz of total spectrum for their entire macro cellular LTE network.

Performance: Wi-Fi has had a clear advantage over cellular networks in terms of bandwidth or peak data rates. But these advantages quickly evaporate as client density, interference, range, and a myriad of other factors impeding signal strength lower realized user data rates.

Without these impediments, LTE and 5G provides a more consistent connectivity and stable wireless performance experience. As the capacity demand increases, the network can be densified with more LTE APs linearly without the complications of interference and channel allocations. With the availability of 5G in CBRS, cellular networks are poised to increase data transfer speeds to multiple Gbps data rates.

Architecture: Perhaps the most profound difference between Wi-Fi and cellular technology is the underlying core architecture. 5G introduces a software-defined architecture with stateless network functions and a service-based network framework. Essentially, the entire networking stack is built in a cloud-native design.

This a fundamental departure from conventional Wi-Fi campus networks because the 5G network operating system inherits all the scalability and dynamic compute power that the cloud offers.

Stateless network functions running as microservices enable a fully resilient and redundant solution running as multiple node clusters. Different network slices with specific QoS attributes can be provided to external applications through network exposure functions in a dynamic and automated fashion.  

With Wi-Fi, the cloud management and orchestration have effectively been retrofitted to equipment that still operates using monolithic operating systems.

The 5G cloud-native approach also provides resiliency with clustering. Dynamic and elastic scalability can be achieved by simply provisioning additional compute resources rather than forklift replacement of hardware appliances.

Configuration: When an LTE or 5G CBRS AP comes online, it automatically initiates a spectrum access request to one of the FCC-certified spectrum access system (SAS) providers. With a “global” knowledge of the entire wireless spectrum, the SAS allocates available bandwidth and channel assignments.

Through self-organizing network (SON) capabilities, clean spectrum is made available for each radio in the enterprise campus while power levels are all optimized centrally to minimize interference and maximize capacity.

This approach is a radical departure from the established Wi-Fi model, where each AP senses its own environment and figure things out on the fly.

Integration: One early concern about the adoption and deployment of enterprise LTE and 5G technology has been its integration with the existing L2/L3 enterprise infrastructure. 

New CBRS-capable APs can plug directly into existing LAN cabling, eliminating the need to deploy a parallel network.  Advanced systems directly integrate with existing enterprise networks by providing flexible options for user traffic forwarding into the existing enterprise network through VLANs, routing, policy, or network address translation (NAT) functions already in place.

This is a big change from how traditional LTE cellular networks that have no integration capabilities and assume a carrier backhaul network. Enterprise policy controls also allow corporate IT departments to map application service level objectives to client device groups and traffic handling policies to integrate with existing security solutions, eliminating the need to define new network and application architectures.

Roaming: As Wi-Fi clients move in the network, the signal strength from different Wi-Fi APs constantly changes. Because clients are making the decision on the best AP to connect to at any given time, consistent connectivity and reliable performance becomes a major issue due to inconsistent implementations by different device vendors.

With cellular wireless, roaming and handoffs between access points are coordinated and controlled by the network infrastructure. As devices move throughout the network, they report channel quality to their serving APs. The network infrastructure decides exactly when to perform handover from one AP to another AP to ensure no loss of connectivity or any data providing a consistent and uninterrupted user experience.

Security: A critical issue for every enterprise, security is handled much differently between Wi-Fi and cellular wireless technologies.

With cellular, there's no concept of an unsecured network with open SSIDs. Data is always encrypted and built into the network core as well as user devices.

Wi-Fi typically requires users to manually enter credentials or IT staff to install certificates on client devices. Cellular wireless is authenticated through either a SIM card provided by the organization or electronically through a programmable embedded SIM (ESIM).  As long as the SIMs are activated within an enterprise system, they will authenticate those devices onto the network. This obviates the need to rely on external radius or AAA servers for cellular-capable clients.

Conclusion

While Wi-Fi will continue to be the workhorse wireless connectivity method for enterprises, the recent introduction of locally available cellular spectrum like CBRS together with the LTE and 5G technology and products will become a much welcome complement to some of the inherent latency, reliability, and coverage challenges organizations face with Wi-Fi as they look to bring greater mobility to essential business applications.

More importantly, with its cloud-native SDN architecture, LTE and 5G technologies give enterprises the ability to finally realize the network agility, scale, and flexibility in their campus networks, essential for business in the 21^st century.

Mehmet Yavuz is the Co-Founder and CTO of Celona.