Tag Archives: 4G

Commercial 5G RAN Backhaul and Fronthaul Overview

January 24, 2017 Wade Leave a comment

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When looking at the RAN you may not think of backhaul or fronthaul as a component, but it is a critical one. Think about it, without backhaul you have no connection to the core, and without fronthaul, you have no connection between the BBU and the radio.

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Let’s start with the backhaul. The backhaul is the connection between the BBU and the core, not a plug and play device just yet, although the small cell has that aspect of it. At the site, you need to have the components to make the connections happen.

First, let’s cover what the backhaul is. Today’s network will have an all-IP backhaul. What this means is that it will have an Ethernet connection to the router. The formats will all be IP-based for 4G and 5G connections. LTE is an all-IP format, as 5G will be. Remember that LTE is one of the building blocks of 5G.

In the days of CDMA and GSM, what we called 3G, they had traditional telco formats like T1 and DS3. These formats worked great at that time, and they were the foundation for what telco had to offer. However, they were over copper. They had limited bandwidth whereas today, with fiber, we can get more bandwidth. When building these systems, there is a need for more and more bandwidth. While DS3 could supply up to 155Mbps of bandwidth, it took more equipment to take it from IP to DS3 format and back again, so now Ethernet connections are the standard in most carrier backhaul systems.

What do you have in the backhaul and fronthaul components? You have the router at the RAN. Chances are the router will be Ethernet

in and Ethernet out. 3G systems used T1 and DS3 formats for the connection to the internet, but now all connections are pretty much IP in and out.

The standard connections could be copper, fiber, or microwave. Fiber is the most common for macro sites because they can deliver speeds greater than 100Mbps, in fact, as we go to 5G, the carriers will expect 1Gbps and up. Microwave is trying to catch up. You can find backhaul that can do 1Gbps links, but the hops are very short and LOS. You also should worry about latency, which is a real issue with fronthaul. We’ll get into that later.

The Wireless Deployment Handbook Paperback and

The Wireless Deployment Handbook eBook that covers professional carrier end to end deployment of LTE small cells, CRAN, and DAS showing you the proper way to plan for deployment then execute.

Then, out of the router, you will have IP access which may go to a switch to distribute the data among the components in the BTS. While the primary purpose is to connect to the BBU for the backhaul, it also passes more information back to the core such as alarms and BTS status. There is also a control channel for the remote MME to manage the BTS. With the IP connection, there are so many things you can monitor and control Most OEMs already have most of this built into their alarming systems. They even look at temperature and open doors. Some carriers are running video back through the backhaul so that they can see what’s going on at the site when no one is supposed to be there. However, the data to the BBU is the top priority, and video is a convenience at best.

Fronthaul is a connection between the BBU and the radio. In the case of a macro site, you have a fiber run, generally in a hybrid cable, between the BBU and the radio head on or at the tower which could be a simple piece of fiber connecting the 2. The reason they call the cable a hybrid is that it will have 3 to 9 or more fiber strands running through it along with power for the radio heads. The power lines are copper lines for DC power up the tower. There can be AC power on these lines, but it would be low power, chances are DC or AC it will be 48V or less. Does it have to be big enough to carry the current to run 3, 6, or 9 radio heads on the tower? There is loss through the cable that, if the engineering is wrong then you could have problems. Radio heads need power to work.

Fronthaul at the tower is straightforward. However, in today’s world, we have small cells and remote radio heads that are part of CRAN, Concentrated RAN, systems, and we have radio heads that could be part of a cRAN, cloud RAN. The idea of these systems is that the controller, a BBU, will be at a remote location controlling several radio heads from that location. Generally, in CRAN they are called BBU hotels, making maintenance and control of multiple radio heads at remote locations a lot easier when the tech can go to the one location to make changes or upgrades.

So, fronthaul will have a router, and most of the time it is fiber. You could also have microwave. Copper is not too common because they want dedicated connections, fiber and microwave offer that. Copper does not.

The issue with fronthaul is that the latency must be very low, there are communication timing issues between the BBU and the Radio Head and the UE that are critical. You don’t want the packet to time out, so you have distance limitations with fiber and microwave. Fiber is clean and works very well. Some microwave systems have longer delays due to the conversion between the data and microwave which can be an issue when transmitting signals because if they time out, then it causes retransmissions which will cause problems in the network if there are too many. Yes, there are delays through the microwave system usually from converting from IP to RF then from RF to IP on both sides. It takes processing power, and if there is a problem with the link, noise or interference, then the RF side will start data recovery and possibly retransmissions.

Let’s look at the backhaul connection. You can have fiber, copper, microwave, or other connections.

Fiber connections:

The most desired connection to the core. Fiber allows a huge amount of bandwidth. Over 1Gbps of bandwidth is available with the right equipment. You have limitations, but it works well.

What options do you have for fiber?

Dark Fiber – this is an unused dedicated fiber optic cable that to the customer’s purpose. In other words, you aren’t sharing it with anyone. A dedicated connection between the RAN and another site or the core or wherever you pay to have it sent. For dark fiber, the customer, you, will need to provide all the equipment to connect. You can get large amounts of bandwidth through dark fiber, 1Gbps, maybe more. Your limitation may be your gear. It is easy to scale dark fiber. If you run your dark fiber, it can be very expensive because you must get permits, right of ways, pay pole rents, maybe trench, and so on. It can get very expensive.
Lit fiber – this is a shared fiber, and you connect to the carrier’s equipment. The carrier could be a telco or fiber carrier or anyone who offer service. It is usually cheaper, but it is not a dedicated connection. It will still connect between 2 points, but the bandwidth may be limited because you are sharing the fiber. You may have a problem scaling up and need to coordinate with the carrier to make changes.

When is fiber used/not used?

Macro sites that require high-capacity could connect to the core or to another macro site to save on costs.
Fronthaul for low latency and high-capacity to connect the BBU to the remote radio head in a CRAN option.
Small cell sites when heavily loaded or no other option is available.
CRAN Hotel BBUs to connect to high-capacity backhaul and to connect to remote radio heads for fronthaul creating a situation where you would have several fiber runs.
In the case of C-RAN, Cloud RAN, it would be to connect the cell that is connected and controlled by a BBU in the cloud. New in 2016 and being tested in China and the USA.
Fiber is not available everywhere. There are issues connecting to fiber in some areas.
Fiber could be cost prohibitive to run to your specific site which has slowed the growth of small cell sites on remote poles. The cost of getting fiber to the pole may be more than the expense of the small cell and the installation of the small cell. That has been a problem that holds back the mass deployment of small cells.
In some cases, you have only one fiber provider to choose from, and their costs may be probative.

The Wireless Deployment Handbook Paperback and

The Wireless Deployment Handbook eBook that covers professional carrier end to end deployment of LTE small cells, CRAN, and DAS showing you the proper way to plan for deployment then execute.

Microwave Connections:

Point to Point, (PTP) is where you have a dedicated microwave shot between to end points.
Point to Multi Point, (PTMP) is where you have one control point connected to multiple endpoints.
Latency varies, and it is hard to capture in a band. Why? Let’s review this list:
- Distance – just like fiber, the farther the data travels, the higher the latency. In microwave, the longer the link, the higher the latency.
- Equipment – specifically the radio equipment in this case. The longer it holds on to a packet the longer the latency. The longer it takes to process the conversion from RF back to IP, the longer the latency. The longer error correction takes to complete the longer the latency.
Spectrum, microwave can be in many spectrums that serve many purposes. High-level explanations for the US market but they could apply to the world. These are the most common. Remember that the distance and dish size and engineering will affect throughput and latency.
- 6GHz range – general for long-range shots. Point to Point LOS (Line of Site) microwave using larger dishes for longer shots. Licensed. Used early on, but the limitations in bandwidth and the large dish size have made them less attractive to modern sites. The dishes are over 6 feet and over. However, the FCC will allow 3-foot dishes in some situations. The limitations are the spectrum, licensing, and potential interference. The FCC did allow larger channels, but the current licenses in the US make it hard to get larger channels. Antenna size is an issue, but because the propagation of 6GHz is great, meaning it can travel far, it makes it hard to license without causing someone else problems. It was great with voice channels when they could travel great distances. Public safety in rural areas relies heavily on this because many of their sites are spread out.
- 11GHz range – generally used for midrange shots. Point to point LOS microwave using mid-size dishes, around 4 foot or so, but the FCC will allow 2-foot dishes. Licensed. Used extensively I the past and is a good midrange solution. The FCC was going to allow smaller dishes, but this band usage is high and very dense in the USA. The throughput is just over 200Mbps if properly engineered.
- 18GHz range – generally used for short to midrange shots. Point to point LOS microwave using 1 to 4-foot dishes. Licensed. These are an attractive solution with high bandwidth. Do the engineering because these links are heavily affected by weather, specifically, rain. Bandwidth through these links could be 100Mbps up to just over 300Mbps
- 23GHzrange – generally for very short hops. Licensed. Point to point LOS microwave using smaller dishes, around 1 to 4 foot. High throughput, 100Mbps and up. Very prone to rain degradation. Very easy to license in the USA.
- 24GHz range – generally used for short hops. Point to point LOS microwave using 1-foot dishes could go down to 8 inches. Not licensed, very easy to license. With a throughput of 100Mbps, some companies can get this band to over 700Mbps with proper engineering, but rain is a factor when it comes to engineering these links. Very limited on distance. Interference is usually low because of the propagation properties of this spectrum. This spectrum is good for short hops.
- 2.4GHz and 5.8GHz range – the ISM band used for short hops, (although I have seen companies connect 15 to 20-mile links). Could be PTP or PTMP. Could be LOS or Near LOS or in some cases non-LOS. Not licensed. This sub 6GHz license free spectrum is a popular choice among non-carriers because the spectrum is free and the hardware is cost-effective using smaller dishes (or panels) which are easy to install and setup. No license makes it easy to deploy anywhere, and the low-cost equipment makes it affordable to deploy anywhere. A short hop solution but there are claims that are using the right size dishes that it can be a long-haul solution. The downside is that it’s prone to interference because anyone can put them up or any Wi-Fi hotspot may affect it. They are easy to deploy. Throughput varies on the engineering but generally, 10Mbps to 150Mbps. I have seen more throughput, but it takes the right design and engineering to get it.
- E-band 71-76GHz and 81 – 86GHz range – generally for very short distances, prone to weather issues. Dishes are very small, under 2 foot. Point to point hops. Licensed links, but light licensed, so getting the license is very easy in the US and Europe. These are a popular choice for short hops that could need up to 1Gbps of throughput. Very high throughput looks like a fiber connection.
- 60GHz – generally for very short hops. Point to point, but there is talk of a multi-point product coming out. Dishes are 6 inches to 2 foot. Throughput is very high, over 1Gbps.

When is Microwave used/not used?

Microwave is a cost-effective alternative to fiber, but can only be used in specific cases. Your paying for the hardware, so CapEx is higher. The OpEx is lower because the only reoccupying cost is license renewal and tower rent if you’re paying it, and maintenance.
Microwave works for macro and small cells for backhaul or fronthaul.
Microwave does have its drawbacks because it is a limited solution, although a very cost-effective one if you’re looking at OpEx.

So, when looking at fronthaul or backhaul you have:

Router.
A connection from point a to point b, fiber, microwave, or copper.
Switch (if needed).

What is LTE UE backhaul?

It is backhaul that uses the carrier’s spectrum, just like the UE, User Equipment, your smartphone. If you have ever used your smartphone as a Wi-Fi hotspot, then you know the concept, using the carrier’s backhaul to create a new hotspot. Now imagine taking your usage and multiply by hundreds or thousands of megabits. The UE backhaul device in something that will use the carrier’s LTE spectrum for backhaul. This is something that is commonly used for internet access when there is no Wi-Fi available. The carriers all sell these units and many of today’s smartphones do something similar. However, they just use the standard signal. Using it for a tiny hotspot and for an eNodeB are 2 different things.

Let’s talk hotspot. Many vendors provide equipment that a user can add coverage quickly and easily. It is a quick Wi-Fi connection to the internet using the carrier’s LTE to connect to the internet. Everyone has Wi-Fi, and there are devices that create an instant hotspot. Verizon has the Mi-Fi, or you can use your smartphone as a hotspot. Every carrier has a wireless modem that you will provide a Wi-Fi hotspot. I think anyone who is reading this knows about the hotspots. I thought it would be a good example to get started.

What is a cell extender? There is a practice where many carriers will use a cell extender that will have a UE relay backhaul to extend the signal. This is also like a smartphone hotspot or a Mi-Fi unit because it was just to help a few customers but extends the carrier’s signal instead of Wi-Fi. This is a type of repeater to extend the macro’s signal, a cell extender. This is a way for the carrier to extend the coverage just a little bit farther. It’s a way to provide coverage someplace quickly and easily. These were common in 2G, 3G, and now LTE. It is a simple and quick way to install a repeater to extend carrier coverage down an ally. In the old days of DAS, this is what they did. They would take the signal where it was strong or use an antenna and amplifier to increase the strength to get it into a dead spot. People paid a lot of money for these systems.

It’s not a simple cell extender, and let me tell you why. Now you are talking about putting the small cell in an area where there is a loading issue. This goes beyond coverage. The data and spectrum usage could go through the roof! If you set it up like a cell extender with backhaul to the macro site, then guess what! You will see an overloaded macro sector! The macro not only has to deal with all its users but all the small cell or Mini macro users too. This sucks up all the spectrum and bandwidth for that sector. What can be done? Read on!

I am bringing this up because now there is talk about using the UE backhaul for small cells, mini-macros, and macro cell sites. It’s making a more powerful cell extender. It sounds like a great idea on the surface. This is a cheap, quick and easy backhaul. However, what is the drawback? It’s not as easy as you think, the carrier needs to set up the donor site properly. I mentioned it earlier, and it is not something you just throw out there to feed a cell site. It draws a ton of data. It sounds like a great idea on the surface. It looks like a cheap, quick and easy backhaul.

The donor site needs to break the bottleneck. You need to dedicate spectrum in the macro eNodeB that will be feeding the UE backhaul. This will alleviate the spectrum usage for the regular users on the macro sector. We don’t want them to get knocked off if the small cell US backhaul overloads the macro. This will make it so that the users on the macro don’t get shut knocked off if the small cell pulls the entire spectrum of its users. This will allow the small cell UE backhaul to have a dedicated pipe. It needs to have dedicated spectrum for this purpose. Then the small cell will know how much backhaul spectrum it has to available. By the way, not an easy change, changes in the eNodeB and possibly the core need to be considered as well as neighboring sites. This “dedicated backhaul spectrum” needs to be set aside for this sector and others too. It takes some planning and changes.

You could still have the data bottleneck at the macro’s backhaul. That’s another issue that needs planning.

So now you dedicated part of the band to the UE backhaul, which seems OK. Remember that the carrier paid a lot of money for that spectrum and now they are choosing to use it for backhaul. So the pipe is limited based on coverage and availability. It is a quick and easy to add UE backhaul, but is this the best use of the spectrum? Will you lose something in this backhaul? Yes, you have delay issues, timing issues, and neighbor issues. All of this is a problem when building a site for any type of real loading. Go to the links below to learn more.

However, what’s the real issue? Is it all the problems I mentioned above? They are all technical issues that good engineers will resolve. This appears to be a cheap and quick solution. But that’s not the real issue, is it? The carriers paid a crap ton of money for spectrum. Is backhaul a smart way to use this resource? Is that billion-dollar investment there to save some CapEx for the company? I thought it was for the customers! Backhaul could have been something in the unlicensed band for a lot less money. It could be a fiber link for more money. Is this an easy out or will it cause problems down the road because the spectrum is only going to get more and more valuable? Do investors want to see that spectrum used this way? I don’t see the auctions being a cheap alternative to providing backhaul.

So just because it looks cheap and easy doesn’t mean it’s a good move strategically. Don’t get me wrong; the UE relays, the repeaters serve an important purpose for coverage and filling holes, I am just saying be strategic and think it through. For more information hit the links below to learn about these solutions.

If delays were lower, this would be a great technology for fronthaul, now that would be something!

Resources:

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Wade4Wireless BlogCast

IWCE 2016 Review on Next Generation of Wireless Networks

March 28, 2016 Wade Leave a comment

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I got back from IWCE 2016 exhausted. There was so much going on at that show that I can’t begin to tell you everything. So what I will go over is what I was able to attend.

Of course, my sessions were really important! To me anyway. I talked about LTE deployment on Monday with others who talked LTE in the session M201 – Next Generation Wireless Networks: 4G, LTE and Broadband.

Mary Walsh of LBC Consultants and Services moderated the session and did a great job of introducing us all and moderating.

I was on the stage with Wim Brouwer of Nokia who spoke of Wi-Fi and how it could be leveraged to maximize LTE coverage. Wim spoke of how Wi-Fi can be used to extend the connection of your device back into the core. How now Wi-Fi does not have to have a specific SSID to connect to the core, but the device would connect through the Wi-Fi to the core. The way I understood it was that the Wi-Fi was merely a pipe to the internet that could connect to the core.

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Patrik Ringqvist, the VP and CTO of Industry and Society for Ericsson spoke about LTE and the progression into 5G. His presentation spoke of the roadmap of VoLTE being ready for services and 5G will use LTE as the foundation to build the newer 5G network.

Dan O’Malley a senior product manager of Cisco gave his talk on what is broadband. While he gave a strong Cisco position it was very interesting. He was able to show us the LTE options and how the broadband system was not only the RAN, but the applications all the way to the core. It was really quite interesting.

Sami Honkaniemi, the managing director or the Mentura Group, gave a great talk on how hybrid systems of the current PTT and LTE systems can co-exist and work together now. This was showing how for mission critical system the LTE would have to have solutions to bridge the open gap between your data on LTE and your mission critical voice on your PTT system which could be DMX, TETRA, P25, or anything else. It looked really cool!

Deploy with the Wireless Deployment Handbook eBook that covers professional carrier end to end deployment of LTE small cells, CRAN, and DAS to show you the proper way to plan for deployment then execute without the mistakes.

Mohan Tammisetti, the CTO and Co-Founder of Virtualcomm, and Gary Monetti, founder and managing director of Monetti and Associates, talked about how the LTE systems can be expanded by using a small interface and a LTE hotspot for emergency situations. This small LTE system extender was really a hit and something that people are interested in because you can expand the network in a crisis situation with little effort! (If the FAA would allow it, which by todays rules, they don’t.) Then you could launch a drone with the hotspot and connect back to the mini core with either Wi-Fi or a back channel, and use that for the first responders on site. If only the FAA could clear up the drone rules for business and emergency use.

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Mohan Tammisetti was planning to do a demo later that evening. I would have loved to have seen the demo but I could not make it. They were going to show the connectivity of the LTE through their tiny core and the hotspot. It was a proof of concept.

I went over the actual LTE Wireless deployment. This was the session that I thought would really highlight what the deployment teams do for LTE. Remember, without the deployment teams, RF Design, installers, tower climbers, optimization teams, site acquisition teams, and all the people that put the system out there, not of the above systems will work. They mean nothing if you keep them in a lab, when they are deployed, that is when they make money!

I was able to absorb quite a bit of information, don’t be afraid to click here to see all of my IWCE 2016 sessions.

I hope that sums it up for you!

Remember, be smart, be safe, and pay attention!

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Wade4Wireless BlogCast

A Story of RF Radiation Poisoning, Blogcast Podcast.

June 7, 2014 Wade

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Hello everybody. I have something special for you today. I have an interview with someone who had RF Radiation poisoning. I wrote a blog a few weeks back that had information in it about the climber that got RF poisoning years ago. His name is Bruce Elle and he was kind enough to let me interview him and broadcast it on my Blog Cast podcast. You can listen to it here or get it on iTunes. It is over an hour so it’s not something that you can fly through.

I did edit out some swear words, the best I could. This is an adult conversation so be aware not to have children around for this. It is over an hour so make time to listen.

Bruce and I have a goal of alerting people of the hazards of RF radiation.We would like make sure you get the point that safety matters. Although we jump around in our conversation we want to drive home that the more you know the more you respect yourself. Respect yourself by looking for ways to keep you healthy, now and in the long run. You have the tools available to ensure that you will be safe barring a major failure, which happens in this business.

We start out by going into Bruce’s background as a climber and the history of the climbing business. Many people think that the way things are now is how it’s always been. Let me tell you it has come a long way. The advances in climbing and safety have been greatly advance through training and education. The thing about climbers is that they hate to change the way they do things. So the key is to show them how it will help them improve their work and be safer. It is hard to slow down a seasoned climber because they want to race up the tower and get the job done. The focus is changing now to make sure that the job is not only done right but safety is the focus.

Focus, this is one thing that we all seem to have a problem with today. When you are going to head up the tower you need to have focus. Someone needs to be looking out for you. That is why I say the crew needs to work together, so that each person is looking for something that they other person may have missed. But, back to the interview.

Bruce talks about how he climbed up the tower that day he got radiated. He was working on the antenna 550 feet up in the air. This was in February and he was sweating while sitting on the antenna. The beacon was on the antenna. For all of you guys that do cellular work may not understand that broadcast antennas were huge and the beacons were on the antenna itself. The antenna would be a huge steel structure made to be mounted on top of a tower. The engineering that went into these was amazing because it would not only radiate but it would need to be a solid steel structure, in this case 50’ high, that you could climb on and it had a beacon on top.

So he was sitting on the antenna was on low power, which in this case was 35,000 watts coming out of the transmitter. This was considered safe at that time, can you believe it? This was considered safe for someone to site on the antenna to change out the beacon. This was considered a normal day at work.

Bruce didn’t have any real pain right away, he just felt really hot for the middle of February. He didn’t feel anything out of the ordinary until he got home that night, then the fever hit. He had to take an ice bath to break the fever. This was the beginning of so many problems that he still deals with today.

Back then he didn’t have RF alert meters, RF suits, or anything like that. Today you have the opportunity to prepare for the unseen hazards of RF radiation by preparing yourself with those tools. Bruce is telling this story so that no other human goes through the pain and suffering he has endured. OK, get it, he is trying to help all of you by sharing his experience. Listen carefully if you want to live a healthy life. Quality of life matters.

Listen to the interview, Bruce lead a climber’s life, not always perfect but he learned on the way. If you are new to this business you will learn a lot about the lifestyle. You can learn from his mistakes and set yourself up for success. Come up with a plan that will work for you. Think about how you can improve your life by reviewing the safety and lifestyle changes that will make you a better person in the long run. Bruce did this to help you all live a better life, he is here to help.

Let me know what you think. I am here to get the word out. I have a book for new climbers here. Like me on Facebook!

Here are some links, old and new, that will shed some light on RF Radiation poisoning.

1980 News on RF Radiation

2013 News on RF Radiation

Wade4Wireless BlogCast

Small Cells? What hell is a small cell?

June 6, 2014 Wade

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OK, what the hell is a small cell? Well, let me tell you about small cells. It’s like putting the cell site where the people are, I mean right where the people using the most data. Suddenly you have a cell that can service a group of people with little RF loss and high data throughput. This is a great thing for carriers because it relieves the macro from the loading it would have from one area in its larger coverage area. That is the goal of the small cell, to alleviate the loading and add coverage. I will concentrate on the outdoor small cells for this article but the indoor may be very similar, just less up front work.

So putting a small cell in should be easy, right? I mean if any of you worked with Wi-Fi you would think you can just pop up an access point and you have an instant hot spot. Well, there is so much more to it than that. The carriers will need to do some work up front is they are to put it in their system. They need to do the RF design, loading study, and coverage analysis. They will probably study the analytics to see where the need is based on coverage and macro cell loading, (data and voice). This is prior to placing the small cells in the macro coverage area. They will look at each sector of a Macro site.

The other challenge is putting the backhaul in. It usually will be fiber, about 10 to 100Gbps backhaul provided to the router connected to the small cell. This is usually a Service Aggregate Router, (SAR). Backhaul quality is everything because you have to make sure you have quality of service. Here is where the LTE small cells have a huge advantage because they have a complete IP backbone, unlike most 3G stuff out there, LTE will be a cleaner deployment. All this is done before they decide to deploy anything.

So mounting the unit will not be too hard, but the connection of the backhaul will require fiber skills. They may have wireless backhaul in some areas, if they connect from the wireless backhaul to the SAR it will be using a fiber jumper. Fiber will be the key to most small cell backhaul connections. The one exception may be if the cable companies step up with a cable backhaul for small cells, they call this Data Over Cable Interface Specification, (DOCSIS), which should be a game changer if it becomes mainstream. Then you could use a standard cable connection for backhaul. This may or may not work because carriers seem to like a dedicated connection back to their core or to one of their cell sites. This is a dedicated connection that would give them security and complete control. It’s what most of them want to do. They don’t just tie into an internet connection like a Wi-Fi connection would. It’s just not that easy at this time. If you’re interested in LTE backhaul, there is a good overview at http://lteuniversity.com/get_trained/expert_opinion1/b/skrishnamurthy/archive/2013/04/01/why-ethernet-backhaul.aspx to explain in more detail.

So let’s look at what we’ve done, we’ve completed the engineering, defined the spots where we wanted it. We then narrowed the spot by finding a mounting location, a pole or a building top, then we found a mounting location that has a fiber connection near it, (fiber is not everywhere), now we finally have the exact location to mount it. Then we have to get a lease, this is all part of site acquisition! We need to work out all of those headaches. If you are not familiar, you don’t just go out and mount it to a pole. You need to find out who has rights to the pole or building, who you lease it through. Then you may or may not need to do a structural analysis on the mounting asset. You will need to do a site design drawing for the documentation prior to the mounting of the asset. What about permits? The local municipality or city wants to take their cut and they want to know what is mounted where. So you will need to make sure all the permitting is completed, this usually slows down the process even more and cost money because you need to file paperwork and often need to hand deliver the documentation.

OK, location found, fiber nearby, mounting asset identified, leasing completed, permitting completed, now we can mount and move ahead, right? OK, now we need to follow the engineering, install the unit, connect the fiber, power to the unit. Did you say power? Did anyone order power? This is something else that needs to be taken care of, power at the pole. So now, at a pole we need fiber and power. Both have a long lead time.

OK, pole, permitting, lease, power, fiber, so now we can mount, and connect it up. Then we’re off to the races. Well, it is mounted to the pole so we are good there. We connected the backhaul to the SAR, we are good there. We now power it up and it should work, right? Make sure the antennas are facing the proper direction and the tilt is set up properly. Now you need to make sure it is provisioned properly, that means that the SAR has to be integrated, then the small cell has to be integrated, then the carrier will want to make a test call and they may or may not want to optimize it with someone doing a walk test. Remember, if the cell has any problems it could create more problems with self interference. The engineering has to take that into consideration. Self interference is taken very seriously because it will create dead spots.

Once the small cell is up and running, life is good in that area, loading is off the macro and on the small cell. The carriers plan to put 10s of thousands of these in. I believe that if the FCC allows more bandwidth to be freed up for LTE, this will be the way that utilities will access their fixed networks. Public Safety already is carving out their chunk of LTE bandwidth. I think that they will rely heavily on small cells because they need coverage in specific areas. Let’s face it, LTE and small cells will be an amazing thing as the world of data takes over. Video will not be just for entertainment, it will be the requirement both ways, video streaming up to the network and down to a device.

OK, now I gave you a background, how does it affect the field worker? Well, you may need to be certified to mount the small cell by the OEM. Remember that the warranty will be affected if you mess something up. Also, this is going to have intricacies that may be affected by how you mount it. Antenna direction, fiber skills, and power connection could all play into this. The Power Distribution Unit (PDU) may be mounted at a different location to power the SAR and Small Cell. You need to know what you are doing to make the connections. It will take skills. Chances are good that you will need to make a test call for the integration phase, provisioning, to be completed. You may need to program the SAR by connecting your laptop to it and uploading a specific configuration file. You need skills! This isn’t Wi-Fi, it’s carrier grade equipment. If you do tower work you know the difference.

I plan to do more on small cells in the future. This is something I have been working on and I have more information to share.

Let me know what you’re struggling with out there in the field. I would like to write about something that could help. Let me know what you think by leaving a comment or hitting me up on Facebook or reach out to me on LinkedIn at www.linkedin.com/in/wadesarver/! I am looking for tower pictures on Facebook page! I am working on a new book, an aid for the field worker and I plan to have a new website ready soon. I have been very busy on other projects but I think that it should happen soon.

Hey, I talk about learning fiber training and I see that JDSU has free webinars on fiber, go their website here and see if you can learn more about fiber! The webinars are free!

To learn more about LTE and Small Cells;

http://lteuniversity.com/get_trained/video_tutorials/default.aspx

http://www.alcatel-lucent.com/solutions/small-cells

http://www.thinksmallcell.com/

http://www.qualcomm.com/solutions/wireless-networks/technologies/1000x-data/small-cells

http://www.3gpp.org/hetnet

http://www.ericsson.com/res/thecompany/docs/press/media_kits/hetnet_infographic_vertical_04.pdf

http://en.wikipedia.org/wiki/Small_cell

http://www.wilson-street.com/2013/10/how-to-deploy-metro-cells-infographic-3-part-1/

http://www.wilson-street.com/2013/10/how-to-deploy-metro-cells-infographic-3-part-2/

http://www.wilson-street.com/2013/07/public-access-small-cells-roadmap-to-successful-deployments/

http://electronicdesign.com/engineering-essentials/understanding-small-cell-and-hetnet-movement

Wade4Wireless BlogCast

RF Awareness, are you aware? Seriously, are you? Episode 002.

June 4, 2014 Wade

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Hello all,

To listen in a new window go here BlogCast!

I am not sure if you are aware but David Horn wrote a blog at http://www.lbagroup.com/blog/fcc-contractor-rf-training/ about the mandate issued by the FCC, http://www.fcc.gov/document/verizon-pay-50k-resolve-radiofrequency-exposure-investigation%20 about Verizon Wireless getting slapped with a $50K fine. So now working there you are required to take RF Awareness training. Why? Because of RF exposure on 2 east coast rooftops. Look at the links, then come on back and I will tell you a story of someone who reached out to me about his RF exposure nightmare. Special thanks to Clifford Wilcox for sharing this on Facebook!

So, I was conversing with someone, (I will reveal his name if he would like me to but not until he explicitly gives me permission) on Facebook about his RF exposure experience. He was working close to an antenna, broadcast, and had major problems afterwards. I am going to quote exactly what he sent to me. He got ill and went to an expert to find out what the problem was, this is the report he got back from them. Let me point out that all of these problems happened in exposure that was less than 45 minutes. It was broadcast so it was high power and this is analog, which as far as I know is no longer used in the US, so things have changed.

Here is the edited report, I removed names and the identification information;

“I have gone through an analysis to try to bracket what I think you may have been exposed to. This is an estimate only! It would take considerably more time to model the batwing elements in detail. Hence, I have used a simple dipole element to estimate local fields near the element and what you might have been exposed to.

My assumptions: Frequency of exposure: NTSC analog TV signal Antenna: 12 bay batwing, Harris TAB-12H Power gain: 11.3 FCC licensed ERP for station at the time: 316 kW

Based on these assumptions, if the station were operating at FULL power of 316 kW ERP, this would imply approximately 932 watts of rms (average) power into each bay of the antenna. If the station was operating at 10% of normal power while you were working on it, the power would be, of course, one-tenth as much, or 93.2 watts per element.

I calculated the electric field strength parallel to a dipole radiator (I realize that the element is really a batwing design but that would take a lot more time to model) and found that at a distance of 1 foot from the element, the maximum electric field strength would be equivalent to a plane wave equivalent power density of about 46 milliwatts per square centimeter at full power or 4.6 milliwatts per square centimeter at one-tenth normal power. Please keep in mind that this is a value where the RF field will be maximum along the radiating element and at a distance of 1 foot from it. Since you were sitting on the element itself, the RF field that at least part of your body would have been exposed to would be much greater. I did not explore calculations at closer distances to the element since this would take additional time to make sure that the theoretical model is calculating correctly.

The accepted maximum permissible exposure (MPE) for occupational exposure in the channel 7 frequency band is 1 milliwatt per square centimeter. These results would suggest that at the presumed safe operating power level of one-tenth normal power, your exposure could easily have been as much as 4.6 times the MPE. Because you were actually sitting right on the element, I would expect your exposure to be substantially greater than my one-foot number but without more careful and detailed analysis, I can’t say exactly what it might have been.

Based on my own experience in climbing towers to make RF field measurements, I know that sometimes there can be miscommunications between the field guys and the tech controlling the station. While I have no information to suggest that this might have been the case, it is relevant to understand that were the station actually operating at its normal full power, the exposure would have been substantially greater, namely, about 46 milliwatts per square centimeter. This is, then, 46 times the MPE and would have resulted in very significant thermal loading on the body!

If the body is exposed to a uniform RF field over the whole body equal to 4.6 times the MPE, the thermal load imposed on the body could be about 130 watts. This power would be distributed throughout the body and while above the accepted limit of about 28 watts (equivalent to exposure at the MPE), would likely have been felt but, in my opinion, not necessarily hazardous. I say this because the MPE has a built-in safety factor of 10 in it. But, if you were exposed to the full power of the station, the thermal load on your body could have been in the neighborhood of 1,300 watts! This is a completely unacceptable value and would be almost five times the hazard threshold (i.e., the hazard threshold can be thought of as a power deposition of about 10 x 28 watts or about 280 watts – in other words, the safety factor of ten has been removed and we are now right at the hazard threshold).

The 1,300 watt thermal load figure is approximately 12 times the body’s basal metabolic rate of 105 watts (i.e., the thermal generation of your body just sitting still). This kind of thermal loading would have been distinctly felt by you as getting hot! It is my understanding that you were told that the station was operating at the so-called safe level of only 1/10th normal power. And, if this is true, then your exposure, while still above regulatory limits, might not have been sufficient to result in a hazard. But, IF, by chance, the station was operating at full power, your exposure would have not only been way, way above regulatory limits, you would have, in my opinion, been sort of cooked. I am only trying to give you some perspective on your possible exposure. Apparently, we don’t really know for absolute sure what power the station was operating at. A first start would be to get copies of the station’s log book during the time you were working on the tower to see if there is validation of what they told you about what power they were really operating at.

In summary, even at the one-tenth power operation, I think that there is a high likelihood that you would have been exposed to RF fields exceeding the worker MPE, though it might have not resulted in reaching the actual hazard level of energy absorption rate. On the other hand, if the station were to have operated at full power, your exposure would have not only exceeded the worker MPE, but it would have likely resulted in significant body heating, well beyond the level that is believed to be hazardous. Because you were exposed while sitting on the top batwing for at least 30 minutes, the issue of time-averaging is not relevant.

One other point. The exposure limits are based on limiting the rate of energy absorption in the body as a whole, what I have been discussing above, and in local parts of the body. You can think of this as though there is a power deposition limit as averaged over the whole body mass as well as a power deposition limit for any given specific point in the body. I have only addressed the case of the average over the whole body in this analysis. The issue of what the localized RF absorption rate may have been in various parts of your body is another question.

I hope this provides useful information to you in regard to your exposure while working on the tower”

USA TV broadcast frequencies [http://en.wikipedia.org/wiki/North_American_television_frequencies]

OK, there are a lot of “what-ifs” in this report but it doesn’t change the fact we all need to be educated and aware. So RF awareness is something we all need! You need to be aware of what is on the tower. I say it all the time, there are more risks than the fall. Wake up people! We need to work together to provide a safe work environment. Let’s learn from these mistakes and make it a safer future for all wireless field workers. Awareness is the first step! Jimi Hendrix asked, “Are you experienced?” [ https://www.youtube.com/watch?v=zg2segLZoeA ]so I am asking you, “Are you aware?” [I don’t have a video, sorry]. Aware of the risks out there beyond the fall. Wake up and be aware! This is a brotherhood and a team, together we learn and teach each other. It’s more that climbers, it’s the wireless field workers that need to work together.

After I put this together I feel we should consider having everyone wear RF alert monitors while working, especially on rooftops. I would only wear them at broadcast sites if I climbed, but I am thinking we should make them standard equipment for all workers at the tower site. Let me know what you think.

OK, shameless plug time. My new book is out, I create a Wireless Field Worker’s Aid for Tower Site Work

I am working on getting out on Amazon, not quite there yet.

PDF on Gumroad (Credit Card) https://gumroad.com/l/RSJZ

PDF on Sellfy (PayPal) https://sellfy.com/p/kxAw/

If you want to reach out to me, Facebook is the best way, Feel free to Twitter or Google+ or email wade4wireless@gmail.com to reach me as well. Or leave a comment on this blog.

Wade4Wireless BlogCast

Tower painters, be smart! Episode 003.

June 4, 2014 Wade

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Hey all,

To listen in a new window go here BlogCast,

If you paint towers then be aware that there may be more dangers than paint dripping on your truck. There are studies out about the long-term effects of inhaling paint. The good news is you will be outside and it’s usually windy when you do it. However, the risk is there. If you can make sure you take the precautions needed so you don’t inhale anything bad. When Utility workers were surveyed who worked with painted for a long time, here is what was reported. This is from a report in PaintSquare,

“The research examined memory, attention and processing speed in 2,143 retirees who had been potentially exposed to three types of solvents in their careers:

33 percent had been exposed to chlorinated solvents;
26 percent had been exposed to benzene; and
25 percent had been exposed to petroleum solvents.

All three solvents are widely used in various products throughout the paint and coatings industry.

The workers’ average lifetime exposure was ranked as none, moderate or high, based on company records, the nature of their jobs, and on when their last exposure occurred.

Participants took eight tests of their memory and thinking skills an average of 10 years after they retired, when they were an average age of 66. (Ninety percent of workers retired between ages 50 and 60.)

Researchers also accounted for factors such as education level, age, smoking and alcohol consumption. They did not control for factors such as cardiovascular disease, diet or physical activity and concede that these may play a role in cognitive functioning.”

Remember that there are more hazards out there than falling. Falling is obvious, it’s the long-term hazards that everyone ignores until they are in the business for 10 or more years. For me it’s my rotator cuffs that just ache, what is it for you?

For more information go to; http://www.paintsquare.com/news/?fuseaction=view&id=11416&nl_versionid=4091

Hey, if you can like me on Facebook and Google+ and Twitter.

My next book is ready, I should release it as soon as I update my website. I am slow but I am trying to get you quality as well as information. Let me know what I can do to help you guys out. If you want me to talk about something, then let me know. I have more about small cells to talk about.

Wade's Working Tips

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