There are good reasons to consider LTE small cells for indoor applications. This is true despite the fact that some tout the continued expansion of Wi-Fi® for wireless coverage in homes and offices. Many question the role of LTE and the mobile operator in these environments. But let’s rethink the strategic use of cellular technologies indoors, such as LTE small cells.
In its July 2015 report NFV: Radio Virtualization in the RAN, ABI Research estimates between 80-90% of wireless traffic originates indoors. This makes the case for offering better wireless coverage using LTE compelling. And through the utilization of voice over LTE (VoLTE), mobile network operators are able to converge multiple networks — 2G, 3G, and 4G to just one, all-IP LTE network. At the same time, LTE small cells offer superior voice quality, greater spectral efficiency for higher throughput, and the ability to improve existing Wi-Fi networks.
As an unscheduled technology, Wi-Fi has many well-known limitations:
- Reduced speed at the access point’s edge
- Poor range due to signal propagation interference at high frequencies through building materials
- Constrained ability to scale such that adding access points doesn’t necessarily increase capacity
- Difficulties with interference and congestion due to contention between user uplinks
- Security problems
For these reasons, end users tend to classify their Wi-Fi voice (VoWi-Fi) and data services as “fair” rather than “great”. Specifically, frustrations with poor voice quality, problematic roaming, and degraded performance when others are using the same Wi-Fi access points are widespread. That’s why the time is right for mobile operators to cost effectively bring superior LTE cellular network quality to indoor users.
LTE efficiency abounds
LTE is a scheduled technology. Its sharing mechanism between uplink and downlink lets it overcome Wi-Fi’s inherent limitations.
As shown in Figure 1, LTE delivers greater voice capacity compared to other technologies. Using 20 MHz of spectrum, LTE can support 400 users compared to only 25 VoWi-Fi or 60 via GSM.
Figure 1. LTE provides greater voice capacity than other technologies
Consider Figure 2. In this example, capacity freed by offering VoLTE is aggregated with the capacity freed as a result of LTE requiring 20% less bandwidth than UMTS networks to deliver the same amount of data. This shift to LTE results in a total estimated 60% gain in overall data capacity compared to continued reliance on UMTS. GSM-based networks benefit from a whopping 15-fold increase in data capacity.
Figure 2. Case study of UMTS 15 MHz spectrum re-farming
LTE deployment and VoLTE utilization lets operators re-farm spectrum, thereby providing more profitable or advantageous services. But in order to re-farm spectrum, operators need to reduce dependency on 2G/3G by bringing LTE indoors.
Without bringing LTE indoors, here’s how it would go: When you’re outside using the LTE network, you’d get to use VoLTE. Then, when you step into your home — where there’s no LTE signal — service would fall back to the 2G/3G network and voice quality would degrade. Not cool. In addition, continued reliance on 2G/3G networks means spectrum isn’t being used as efficiently and overall network capacity isn’t being maximized.
VoLTE hands-down winner
Signals Ahead research has conducted multiple comprehensive series of tests of VoLTE versus Skype/ VoWi-Fi using live networks. They have evaluated numerous parameters of these services, including:
- Voice quality
- Resource utilization
- Call set-up time
- Call reliability
- Battery lifetime
Results from their Part 1 study showed that VoLTE is the hands-down winner. In fact, VoLTE had superior Mean Opinion Scores (MOS) across the board. VoLTE delivered better voice quality due to clearer voice and less noise while minimizing use of network resources.
Adding to the good news, call set-up time dropped from 5 to 2.9 seconds, call reliability was comparable to circuit switch fallback, and VoLTE battery life was 56% longer than for Skype. Taken together, these results produced higher customer satisfaction and higher net promoter scores — 2 critical measures of customer experience management.
Looking more closely at the resource utilization results, we see the many direct benefits of VoLTE. VoLTE consumed:
- 10 times less bandwidth
- 7 times fewer resource blocks
- 5 times fewer transmission time intervals
- 6 times fewer physical downlink control channel grants
Moreover, LTE transmitted 4 times less often, compressed the signaling header 89%, and required 2.3 dB less power from the user equipment to the tower. All this means that VoLTE reduces the opportunity cost of delivering voice service. Plus, increased spectral efficiency leaves more capacity for profitable video or data applications.
Greater spectral efficiency and superior voice both benefit users and operators. But how can LTE be integrated into existing home and enterprise Wi-Fi infrastructures?
By using a Wi-Fi boost solution, interference and reduced data rates resulting from user uplink contention are eliminated. A unique combination of Wi-Fi and cutting-edge LTE small cell technology, this boost solution can double aggregate capacity per access point while freeing up Wi-Fi to do what it does best — provide download capacity. This approach also leverages the pre-existing access points and user equipment.
By using LTE in the home for uplink traffic, a single user’s Wi-Fi downlink experience can increase 20-30% (compared to reliance on Wi-Fi alone for both uplink and downlink). In a multi-user environment such as an enterprise, users can experience a 70% increase in downlink speed. On top of that, Wi-Fi range is improved by a factor of 2 or more.
In addition, LTE’s fast uplink speeds and broad range makes for a 10-fold increase (or more) in uplink speed compared to Wi-Fi alone. And, they can use LTE download on hot standby.
All in all, the combination of Wi-Fi with LTE small cells plays to the strengths of each technology. Wi-Fi is best for downlink while scheduled LTE technology is best at handling uplink traffic. And with cost-effective LTE small cells, operators can deliver superior quality of experience to home and enterprise users while opening up the possibility for spectrum re-farming.
T-Mobile USA case study
9961 Multi-standard Home Cell product web page
Wireless Unified Networks solution web page
Our authors look forward to your questions and comments.