Demonstration of TLPS
A couple of weeks ago, I had the opportunity to observe a demonstration of Globalstar's TLPS, which has been installed in a school in the Washington, D.C. area. Regular
Lens readers know that I have been writing about TLPS for some time now. TLPS, or terrestrial low power service, uses a slice of spectrum licensed to Globalstar in the 2.4 GHz band, combined with unlicensed spectrum, as a supplemental channel for Wi-Fi. Currently, channels 1, 6, & 11 in the 2.4 GHz band are used for Wi-Fi. Globalstar has petitioned the FCC to allow it to open channel 14, which would add much needed capacity to a congested Wi-Fi band.
We all know, and experience, the congestion and capacity issues of Wi-Fi, due to the multitude of competing devices and demand for data. Over the past couple of years, additional channels in the 5 GHz band have been opened up for Wi-Fi, a result of the hard work by key players such as Google, industry groups, and the FCC. Globalstar's petition, if successful, would open up Channel 14 in the 2.4 GHz band, providing needed additional capacity and also, potentially, some relief in the crowded channels 1, 6, & 11. The FCC is giving serious consideration to Globalstar's petition, and could possibly make a decision in the coming months.
During this period, Globalstar has hosted numerous installations, demonstrations, and simulations of TLPS. I had the opportunity to see a demo of the TLPS deployment at the Washington School for Girls in Washington, D.C. Also at the demo were FCC Commissioner Pai and Gigi Sohn, Counselor to FCC Chairman Wheeler. The purpose of the deployment is to integrate Channel 14 into the existing wireless network and measure the results.
The space is 12,500 square feet on the second floor of the Town Hall Education Arts Recreation Campus (THEARC) in S.E DC. Multiple 2.4 GHz wireless networks are used in the building, by the school and other tenants. Due to the number of users, networks, and somewhat challenging building environment and layout, there had been issues with the performance and reliability of existing Wi-Fi.
In this deployment, three Ruckus APs, capable of operating on Channels 1, 6, 11,
and 14 were added to the existing school network of three Aruba APs running on Channel 11. Globalstar supplied 25 Chromebook computers to the school as part of the deployment.
Results are shown in the table below, per AP assigned to a specific channel and aggregated across channels the channels. In the baseline test, 4 APs using channels 1,6, and 11 were used. In Scenario #2, Channel 14 was added.
|
Measurement
|
Scenario
|
DL (Mbps)
|
UL (Mbps)
|
|
Baseline
|
4 laptops connected to one AP;
4 APs operating on Channels 1,6,11
|
20-30
102 aggregated
|
18-27
89 aggregated
|
|
Network with TLPS enabled
|
Previous test but with Channel 14 added
|
28-30 on 1,6,11;
59 on Ch.14
147 aggregated
|
23-28 on.1,6,11;
40 on Ch.14
120 aggregated
|
As the table above shows, the addition of Channel 14 resulted in a downlink capacity increase of 45% and an uplink capacity increase of 34%. Additionally, there were modest performance improvements in Channels 1, 6, and 11. Not only did Channel 14 operations have no negative impact on the performance of the other channels, but their performance actually
improved with the addition of Channel 14 as traffic on each channel was lessened when Channel 14 became available.
In addition to the quantitative results shown by the tests, we heard from the school's network manager and had informal conversations with a couple of teachers and administrators. All noted that Wi-Fi performance had improved significantly, both in terms of speed and reliability. The addition of channel 14 from the end-user perspective was seamless - there was no special configuration required for channel 14, and the performance of channels 1, 6, and 11 was not negatively impacted. The general observation was that Wi-Fi was faster and performance more consistent.
We know that there are efforts on multiple fronts to increase network capacity and performance: In Wi-Fi with additional channels at 5 GHz.; and in cellular with upcoming 600 MHz spectrum auctions, 2.5 GHz deployments by Sprint, the possibility of LTE-Unlicensed, and various LTE-Advanced approaches such as channel aggregation.
TLPS provides an important near-term opportunity to open up new space in the 2.4 GHz band for a premium type Wi-Fi service, while also improving performance of Wi-Fi on existing channels.
