FOA Guide to Fiber Optics

Topic: Comparing DAS, Small Cells And WiFi

Table of Contents: The FOA Reference Guide


Comparing DAS, Small Cells And WiFi

If you say "wireless" to an IT or LAN person, they think WiFi. But to a telecom person they think cellular. FOA's involvement is based on trying to understand the infrastructure to support wireless, OSP or premises, WiFi or cellular, tower site or small cell. We're basically outsiders on the technology looking at the infrastructure to support them. Recently we've been trying to understand the technologies, markets and applications for both to better include the two technologies in our training and certification programs.

The initial question we had dealt with distinguishing DAS (distributed antenna systems for cellular) and small cells (also cellular). In most ways they seem to be very similar, except perhaps DAS is indoors and small cells outdoors.

We've started to interview insiders in both technologies to try to understand how they work and why we should have both. Right off, we found that there appears to be a general lack of technical understanding about the other from almost everybody we talk to who works with one of them. And we're talking real basics - what frequencies are used, protocols, coverage, bandwidth, etc. etc. etc. Even the jargon is different, but that's not unexpected. So we've tried to consolidate information on the three different premises wireless technologies appropriate for general usage. Over time we expect to refine this comparison with more data and user feedback. (got any? send it to us)

Based on the current evaluation, WiFi is essential to premises spaces and because of the ubiquity of WiFi, it is inexpensive. However, WiFi connections for cellular mobile devices appears to have not yet been refined sufficiently to provide reliable coverage for cellular voice, but data is good and video, maybe. Given the cost structure of data plans, using cellular for video can be very expensive but WiFi is preferable since it is only limited by bandwidth.

The choice between small cell and DAS in premises spaces is simple - small cells are generally single carrier connections and that is too limiting for most users. DAS is similar technology but has the advantage of offering multiple service providers. If better cellular service is desired indoors and WiFi connections for cellular calls is unreliable, a DAS is the best solution.

Small cells appear to be a good solution for better cellular service outdoors in metropolitan areas but the capital costs for building systems is quite high - Deloitte, you might remember from an earlier FOA Newsletter, forecast a cost of over $200 billion. It makes one wonder if the carriers can make that investment while simultaneously investing in 5G.


Premises Wireless
WiFi DAS (Cellular)
Small Cell (Cellular)
Connects to: PCs, tablets, phones, many other devices Phones, tablets, some other devices Phones, tablets, some other devices
Usage Free, sponsored Paid Paid
Origin Private, LAN Public, telco Public, telco
Frequency Ranges Unlicensed
2.5GHz (802.11n, 14 - 40MHz channels, 3 max non-overlapping)
5GHz (802.11ac or 802.11n, 24 -  80 MHz channels, 23 max non-overlapping)(more bandwidth, less range)
Licensed
3G:  850, 1700, 1900, 2100 MHz
4G/LTE:  600, 700, 850, 1700, 1900, 2100, 2300, 2500 MHz
CBRS (Citizens band Radio Service, shared, unlicensed): 3600 MHz, 20MHz channels,
5G: Eur: 24-27GHz, US: 37-48GHz, 71-74GHz
Licensed
3G:  850, 1700, 1900, 2100 MHz
4G/LTE:  600, 700, 850, 1700, 1900, 2100, 2300, 2500 MHz
CBRS (Citizens band Radio Service, shared, unlicensed): 3600 MHz,
20MHz channels,
5G: Eur: 24-27GHz, US: 37-48GHz, 71-74GHz
Connects to: Internet Multiple telco carriers Single telco carrier
Mobility Log in to each new private system required, limited handoffs between WiFi systems or WiFi and cellular
Seamless handoffs Seamless handoffs subject to coverage
BYOD (bring your own device) OK OK Depends on service provider device connects to
Optimized for Data 3G: voice
4G/LTE/5G: data
3G: voice
4G/LTE/5G: data
Data: Max data rate: 802.11n: ~35-300Mb/s
802.11ac: ~400Mb/s - 7 Gb/s (MIMO)
4G/LTE: ~100Mb/s
5G: ~Gb/s (proposed)
4G/LTE: ~100Mb/s
5G: ~Gb/s (proposed)
Voice VoIP: good
Cellular on WiFi: not optimal, depends on device/carrier/implementation
Good with proper coverage Good with proper coverage
Video Good 4G/LTE: marginal, expensive
5G: Good (proposed), cost?
4G/LTE: marginal, expensive
5G: Good (proposed), cost?
Cabling (typical)
Fiber backbone to Cat 5, POE
Fiber, sometimes Cat 5
Fiber, sometimes Cat 5
Summary
Best for data on PCs, tablets, smartphones, good for VoIP systems, marginal on cellular devices
Best for cellular devices since can cover all service providers, not optimal for high throughput data (today, future 5G ?)
Good for cellular devices but can cover only one service provider, not optimal for high throughput data (today, future 5G ?)

Learn more about how small cells and other technologies contribute to "smart cities."

More On Fiber For Wireless
FTTA- Fiber To The Antenna  
Testing FTTC Fiber  
DAS - Distributed Antenna Systems  
WiFi - Premises Wireless  






 


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