The changing RF landscape for WISPs

Recently, there have been some discussions on Facebook about waining support for 2.4GHZ .  KP Performance recently published a Future of 5GHZ and beyond blog post. So why all this focus on 5GHZ and why are people forgetting about 2.4?

To answer this question, we need to update our thinking on the trends in networks, not just wireless networks.  Customers are demanding more and more speed. Network backbones and delivery nodes have to be updated to keep up with this demand. For anything but 802.11 wifi,2.4GHZ can’t keep up with the bandwidth needs.

One of the significant limitations of many 2.4 radios is they use frequency-hopping spread spectrum (FHSS) and/or direct-sequence spread spectrum (DSSS) modulation. Due to 2.4GHZ being older, the chipsets have evolved around these modulation methods because of age.  When you compare 2.4GHZ to 5GHZ radios running OFDM, you start to see a significant difference.  In a nutshell, OFDM allows for higher throughput. If you want to read all about the differences in the protocols here ya go:

Secondly, is the amount of spectrum available.  More spectrum means more channels to use, which translates into a high chance of mitigating interference. This interference can be self-induced or from external sources. To use an analogy, the more rooms a building has, the more simultaneous conversations can happen without noise in 2.4GHZ we only have 3 non-overlapping channels at 20mhz. Remember the part about more and more customers wanting more bandwidth? In the wireless world, one of the ways to increase capacity on your APs is to increase the channel width. Once you increase 2.4 to 30 or 40 MHz, you do not have much room to deal with noise because your available channels have shrunk.

One of the biggest arguments in support of using 2.4GHZ for a WISP environment is the physics.  Lower frequencies penetrate trees and foliage better. As with anything, there is a tradeoff.  As the signal is absorbed, so is the available “air time” for transmission of data.  As the signal travels through stuff, the radios on both sides have to reduce their modulation rates to deal with the loss of signal.  Lower modulation rates mean lower throughput for customers.  This might be fine for customers who have no other choice.  This thinking is not a long term play.

With LTE especially, the traditional thinking is being uprooted.  Multiple streams to the customer as well as various paths for the signal due to antenna stacking are allowing radios to penetrate this same foliage just as well as a 2.4 signal, but delivering more bandwidth. These systems are becoming more and more carrier class.  As the internet evolves and becomes more and more critical, ISPs are having to step up their services.  The FCC  says the definition of broadband is at least 25 meg download. A 2.4 radio just can’t keep up in a WISP environment.  I am seeing 10 meg becoming the minimum customers want. Can you get by with smaller packages? Yes, but how long can you maintain that as the customer demand grows?

So what is the answer? Cell sizes are shrinking.  This is helping 2.4 hold on.  The less expensive radios can be deployed to less dense areas and still provide decent speeds to customers.  This same trend allows 5GHZ cells to be deployed as well. With less things to go through, 5GHZ can perform in modern networks at higher modulation rates.  Antenna manufacturers are also spending R&D to get the most out of their 5GHZ antennas. More money in the pipeline means stronger products. My clients are typically deploying 3.65 and 5GHZ on their towers.  LTE is changing RF WISP design and taking the place of 2.4 and 900.

Cambium Linkplanner 5.1 released


New or changed features

  • PTP 820
    • Addition of PTP 820E in the 80 GHz band
    • Added 7 GHz FCC band to PTP 820C HP and PTP 820F RFU-D-HP
    • Added warranties for PTP 820F
  • ePMP
    • Add ePMP 3000L, Force 300-CSM and Force 130

These products are only available in the 5 GHz band and please note that the Force 300-CSM and Force 130 are not supported in United States, Canada and associated FCC countries.

  • PMP 450 family
    • Added notification of pending End of Life for PTP 450 and PMP 450 SM
    • PMP 450b SM changed to use the new parts which can be used for either PTP or PMP
  • General
    • Warranties – updated default warranties in line with changes to warranty options
    • Changed the best server to process in batches and report high level results at the end of each batch to show progress when analysing large projects and reduce “Not responding” issues.
    • Discontinued RF Elements SH horn antennas and added similar HG3 horn antennas
    • Added a “Highlight AP” function to the offline map which when selected will grey out all other APs and associated SMs to allow focus on the SMs connected to the selected AP.


Select the new icon, shown in the red box above and then select the AP that you want to highlight, remember that you can use the up and down arrow keys to toggle between overlapping APs to select the one that you require. Click outside the AP coverage area to return the screen to normal but leaving the highlighter enabled or click on the pointer option on the toolbar to disable the highlight function.

Bug Fixes

  • Corrected memory leaks when loading a project, which was introduced in V5.0.0 and affected opening large project files
  • Added missing dual splitter to PTP 820C 4+0 Cross-Polar and 4+0 XPIC
  • Corrected issue if all the text is deleted in a table cell
  • Stopped errors when deleting AP or SM from the Subscriber Site List tree
  • Force the proxy port settings to be an integer
  • Added missing power cord in PMP 450i AP BOM
  • Prevented errors when creating hub level reports
  • Ensure that HCMP Expert mode DL and UL slot allocations are loaded correctly
  • Corrected error on PTP 550 2+0 when changing regulation
  • Improved Options dialog label formatting
  • Prevent errors when changing quantities in the hub BOM
  • Corrected error when selecting the original PMP 450i integrated AP on 5.2 GHz/Canada
  • Allowed custom clutter categories to load correctly from project file
  • Mac only – Disabled Delete option on the hub using the right-click menu in the tree
  • Mac only – corrected issue preventing users from selecting antennas in the BOM Estimates and equipment templates
  • Mac only – prevent errors when clicking quickly multiple times in BOM quantity cells