I have been wanting to write this article for awhile. When the topic is fresh in my mind I am usually too tired from a day of climbing. By the time things get around the lessons learned have escaped me. So, after a day of being in the sun on a 150 foot monopole I figured I would share some best practices. These are aimed toward the WISP who wants to maximize their climbs.
1.Tighten sector brackets on the ground and other bolts. If it is holding it to the sector tighten it. The idea is the climber wants to be able to position the antenna against the mounting pole as easily as possible without needing extra hands. Sometimes having both hands free is a challenge. If you want to adjust downtilt on the ground the following links can help speed up the process. This is not necessary nor is it a requirement. It just is one less thing to do in the air. Some helpful Links:
I am planning on another blog article about downtilt calculations and my thoughts. We will go into this in a future post.
2.For Wireless backhaul shots in the 0-7 mile range use google earth. Draw a line between the two points and use two reference points to get in the neighborhood. By looking at the below screenshot I know to align my path over the edge of the building almost at the base of the tower. This helped me determine mounting location and get a pretty close aim. You can get fancy with compasses, GPS alignment devices, and other high-tech toys, but people are typically visual people. Having a reference point is easier on the mind than having a number like 121 degrees off north. Microwave shots are a different beast so don’t lump tight beamwidth licensed links into the above statement.
3.Don’t get too hung up on labels. Instead I like to color code things. If I am putting up 3 sectors I will get some colored tape and label them with a blue piece, a red piece, and a green piece. This way if the client wants to have a sector facing north We have the software labeled blue. I can identify color and tell the ground crew I faced the blue sector north. Makes things easier in the high stress environment of being hundreds of feet in the air. The cellular companies have some standardized labeling of their sectors:
Alpha is the North FACING vertical antenna on the cell tower
Beta is the Southeast FACING vertical antenna on the cell tower
Gamma is the Southwest FACING vertical antenna on the cell tower
I would suggest come up with a SOP for all your tower deployments, but be flexible. Due to the various mounting locations it’s not always prudent to cookie cutter a WISP deployment like the cellular folks do. I have installed gear on towers where you have a small corner of a rooftop or grain facility. Due to other things being up there, the fact you are trading service or paying very little, your mounting options may be limited.
4.On a related note color code everything. If you use colored tape, make sure to match the ethernet cables going to the sectors. This way it is easier to identify the cable going to the sector. This also helps in easier identification of where things are plugged in.
5.There are six phases of the a WISP deployment.
Stage one- assembly and staging
Stage two – Mounting radio equipment and antennas
Stage three – Connecting power and connectivity.
Stage four – Physical adjustment and tuning
Stage five – Testing and tweaking
Stage six – cleanup and zip up
Think about each of these. This will be another future blog post.
6.Have a plan of action. Have a flexible order of doing things. Be able to adjust this on the fly due to various factors. Sometimes is makes sense to mount the sectors, backhauls, and any other boxes at the top. Once you have them mounted then make the connections. Other times it may make sense to run the cable when you mount the device.
7. Have a loadout of specific tools in a bucket or tool pouch. I like to include the following:
Knife – Automatic or assisted opening
Slip Joint pliers
Other tools such as ratchet wrenches, different sized tools, power tools, etc. are handy, and can make life easier. However, the above tools will allow you to 90% of what you need to do to install or remove most WISP equipment. The flat screwdriver can be used to pry things loose or for leverage.
8.If you can do it on the ground do it. Terminating and testing cat-5 is easier on the ground than 150 feet in the air.
9. Train the ground crew to think about how this affects someone on the tower. Most of the time folks don’t have the luxury of platforms. So they are hanging off the tower in awkward positions. Doing a pull with 3 sectors attached to a load line might seem like you are saving time, but it might make things complicated for the climber. Sometimes, 3 pulls might make their life easier. They only have to deal with one thing at a time. They aren’t fighting trying to unhook multiple antennas or figuring out what is what. This is where straps come in very handy. A strap allows a climber some extra flexibility to move things around and position them better.
10.Have a checklist of sorts. This can be a running thing as you go along. I routinely tell the ground crew to remind me to do this. If you have someone writing this stuff down they can read it back to you before you come down.
There are a great variety of tools, tricks, and ways of putting stuff on the tower. Many people have their own ways of doing things. These are just some of the best practices I have come up with through experience. We could debate tape vs zip ties and other things for hours. Please leave comments and some tips that make your life easier.
Mimosa B5 Lite
Telrad 3.65 LTE
From the Bitlomat Page:
Bitlomat has developed Passport, an innovative point-to-multipoint TDM-derived protocol with the needs of large scale outdoor networks and wireless internet service providers (WISPs) in mind.
Passport resolves the hidden terminal issue that is the root cause of poor performance in many large scale wireless networks, and provides the network operator with the highest throughput and spectrum efficiency available on the market.
Passport implements an advanced medium access control protocol to allow for fine-grain configuration of the guaranteed bandwidth that each client should have in the network. A WISP can create different classes of traffic and users, providing different guaranteed throughput on the same wireless network based on the access level or SLA that each user has subscribed to.
Passport is available for free for all Bitlomat products and comes embedded in the Bitlomat firmare.
Read More here..
The news that really makes you want to check it out:
Not only does Passport offer major improvements in throughput, bandwidth, latency, etc. but it’s now available for download to be flashed on to your existing network!
Read More here..
PDF Release notes can be found at http://community.cambiumnetworks.com/t5/ePMP-1000/New-ePMP-Release-2-3-1-now-available/m-p/37067#U37067
o RFC1213 supports standard interface MIBs. Items such as Ethernet interface Tx/Rx and
corresponding stats are now supported per the standard RFC. This allows users to utilize 3rd party monitoring tools that support RFC1213
• Separate Management IP when SM is in NAT mode
o Separate Wireless Management IP will provide the ability to separate management traffic from user traffic when the SM is configured in NAT mode providing separate management access to the SM. This includes the ability to have a separate management interface when PPPoE is enabled on the SM.
• ARP table display
o Displays all the ARP entries for interfaces present in the routing table
• VoIP helper functionality under NAT
o When the SM is in NAT mode, ePMP inspects SDP packets and automatically creates appropriate
Some of you have been asking for some photos of the Bitlomat CPE in real life.
The last photo is side by side compared to a UBNT M5 Nano
Almost all the time I get asked: “How many clients can an AP handle?” . My answer is always a very long and drawn out one. There is no set in stone answer. There are many factors which can affect this. I will go into some of these and then explain how to calculate this.
Some things that we will assume.
1.You are calculating on an 802.11N Ap with some kind of polling (TDMA, NSTREME, AIRMAX, etc)
2.You know the MCS values and/or data rates at channel widths.
3.When I say in an ideal situation I mean basically in the lab. This is our baseline. This means no outside noise, everything is working properly, and all the connected clients are excellent.
Before I get into what affects how many clients can an AP handle we need to shift our thinking a little. We don’t think in terms of how many clients can an AP handle. We need to think in terms of how much capacity an AP has. This is very important to think in these terms. If you do so things will become more clear and more quantifiable.
So now, on to what affects the total capacity of an AP.
1.The channel width. In and ideal situation you will get more Capacity out of a 20 mhz channel than you will a 10mhz channel.
2.Noise. In the real world you will have interference. If you have interference the noise floor drops, customer signals can’t reach maximum modulation, and there are retransmits.
3.Plain old signal. Things such as trees, distance, fresnel zone, and antenna gain all affect signal
4.The speed you are giving to each customer.
5.Overselling. The concept of overselling has been around since the dial-up days. You are betting your customers are not all online at the same exact time doing the exact same stuff. So you can oversell your capacity. I will explain this a little more in a bit how this factors in.
Okay, so let’s dive into this. I am going to use a Ubiquity Rocket M5 as an example. Again, this can be applied to any polling type N radio.
Say we have a Rocket M5. At a 20MHZ channel the best modulation this M5 will do is MCS 15 at 130 Megs of over the air. What do you mean Over the Air? Well there is a difference between actual throughput and the Wireless Data Rate (aka over the air). Your actual throughput/capacity will be 1/2 of the over the air rate minus a little for overhead. I factor in 10% overhead for easy figuring.
Back to our figuring. You have 130 megs of capacity on your AP in an ideal situation on a 20 mhz channel. If we do our math:
130 / 2 = 65 Megs of Capacity to sell on the AP.
Now here comes the overselling part.
If we oversell at a 2:1 ratio we have 130 Megs of capacity on the AP.
If we oversell at a 3:1 ratio we have 195 megs of capacity on the AP.
We can do higher ratios, but it starts to become a moving target. With the spread of Netflix, Youtube, Hulu, and other streaming services the average customer is sucking down more and more bandwidth for longer periods of time. Think of a restaurant with so many tables. If your customers are staying longer and longer, you don’t have as much seating capacity to turn over for new people to sit down and consume your food. This is for another blog post.
So, let’s say we are overselling at 3:1. We have 195 megs of capacity. We now need to think about what packages we are selling to our customers. If they are all say 5 meg packages, this means we can safely sell 39 connections to the AP. 195 / 5 = 39. You can figure up the math if you have 3 Meg, 10 meg, or a mixture.
Now to the real world (aka why do my customers hate me and my AP sucks?).
The following is a real AP in the wild. Blacked out to protect the innocent from script kiddies.
20 MHZ Channel
Capacity at 45% . This is more important than anything, even CCQ.
43 clients associated.
Let’s apply our math we learned earlier. We know a 20 mhz channel nets us MCS15 – 130 Megs
Here is the kicker. Our capacity is at 45%. This means we only have 45% of 130 megs of Over the air capacity. Take this in half (130 / 2= 65 45% of 65 = 29.25.
This means all 43 of these customers are sharing 29 megs of capacity on the AP. And the quality isn’t the greatest (37%). So this means there are retransmissions going on between the client and the AP. The client can’t talk as fast as it is capable of in most cases. This means you can’t oversell the AP as much due to the quality of the signals being poor. It is important to note I am talking about the quality and capacity of the signals, not signal strengths.
If those 43 people are all paying for, let’s say, 2 Megs download. That means your AP needs to support a minimum of 86 megs. Thats without overselling. We only have 29 megs in the current state!
We need to get those capacity numbers up. How do we do that?
1. Channel selection. A noisy channel will drag everyone down.
2. Antenna gain. This can be done at both the client and the AP. A higher gain or better quality antenna can cause the clients to “hear” better. You might not get an increase in signal strengths, but you are looking for an increase in quality. I use a loudspeaker metaphor. You can hear a loudspeaker from a far distance, but you might not always be able to make out what is being said. If you can somehow make out what is being said more clearly, then you don’t have to have the speaker turn up the volume.
3. Shielding. This helps eliminate the amount of stuff a client or AP hears.
4. Channel Width. Sometimes dropping the channel width down can increase signals, thus raising the overall capacity. Keep in mind it will lessen the overall capacity of the AP.
5.Simply getting rid of customers that shouldn’t be installed. We have all done installs that were iffy. These can drag down the overall capacity.
I hope this has helped understand. The biggest thing I want you all to take away from this is think in terms of the amount of capacity you have to sell, not the number of connections.