Wireless 101

It’s important to ask yourself some important questions when looking for the right wireless system. One way to think of your wireless network is as a “highway” between locations.

You will want to build an infrastructure similar to the roadways you travel over each day. The same issues that a road designer ask themselves, you will need to ask yourself questions such as:

• Who needs access to the system?
• What speed and latency do these users or applications need on the system?
• What are the on-ramps and off-ramps for adding others to the system?
• Do the users need a dedicated, secure lane on the highway or can they use a shared lane with others where the throughput may vary depending on traffic?
• What is the primary purpose of the system?
• What location or locations do I need to connect?
• What kind of traffic will go over this “highway”?

It’s important to ask yourself some important questions when looking for the right wireless system. One way to think of your wireless network is as a “highway” between locations.

You will want to build an infrastructure similar to the roadways you travel over each day. The same issues that a road designer ask themselves, you will need to ask yourself questions such as:

• Who needs access to the system?
• What speed and latency do these users or applications need on the system?
• What are the on-ramps and off-ramps for adding others to the system?
• Do the users need a dedicated, secure lane on the highway or can they use a shared lane with others where the throughput may vary depending on traffic?
• What is the primary purpose of the system?
• What location or locations do I need to connect?
• What kind of traffic will go over this “highway”?

Digital video has become a critical aspect of remote video surveillance applications. Wireless technology has enabled video surveillance to be deployed across wide areas without the costs associated with traditional hard-wired connectivity. Municipalities, public safety organizations and transportation services rely heavily on real-time video monitoring for security, traffic management and emergency operations.

Video surveillance networks can span hundreds of square miles and use hundreds of networked video cameras. Thus, it is critical for the wireless network supporting these cameras — the backhaul network in particular — to have sufficient capacity and lowest latency to carry the aggregated camera traffic to the various video surveillance centers and monitoring agencies.

Capacity needs can add up fast, as high quality video cameras can each generate 0.5 – 3 Mbps of traffic, depending on image resolution, frame rate, video compression type, number of monitoring and recording hours, and whether cameras operate continuously or are event driven.  The backhaul capacity needed to transport traffic from 10 locations with 5 cameras each to a monitoring control center could be as much as 150 Mbps of unidirectional traffic.

Please consult your local wireless integrator for assistance with planning and deploying these types of applications.

900 MHz radios are used in industrial applications, such as oilfield, water/electric utility, and even municipal traffic for supervisory control and data acquisition (SCADA) and various process control applications. Some advantages of 900 MHz over its unlicensed industrial, scientific, and medical (ISM) band cousins, 2.4 GHz and 5.8 GHz, include longer, reliable distance reach and penetration of obstructions such as trees and leaves when faced with Near-Line-of-Sight and Non-Line-of-Sight conditions.

900 MHz wireless solutions provide long distance communications over licensed radio bands, allowing users to interface with both Ethernet and serial devices such programmable logic controllers (PLCs), remote terminal unities (RTUs0, and meters with host monitoring and control systems.

Although 900 MHz supports lower data rates (as low as 50 Kbps) than 2.4 GHz and 5.8 GHz frequencies, for most SCADA operations that is sufficient as the type of data being sent requires little bandwidth. Many times the type of data transferred in these 900 MHz applications is a simple on or off control message.

Lower Latency
More hops in fiber-optic networks lead to more processing latency and noise. A fiber network encompassing a city has to typically pass more points than a microwave to arrive at the final point. The reduced number of hops in microwave networks results in a lower end-to-end latency. Even a gain of a few milliseconds can add up to a sizable advantage for businesses and deliver a better Internet experience with lower latency when compared to fiber- optic networks. For businesses using phone systems such as VoIP, a great advantage of using low latency microwave fixed wireless Internet connection is good call quality in comparison to what is offered when using fiber-optic networks. Also for industries such as finance and stock exchanges, having minimal latency in such networks is extremely critical.

Reliability
When your business operations depend upon connectivity to the Internet, the reliability of your broadband connection is critical. One of the downfalls of fiber-optic networks is that the cable often runs underground, this leaves the network vulnerable to disruption due to damage caused by work being done in the street or the building. In comparison, a microwave fixed wireless connection is a point-to-point connection that meets or exceeds the reliability of fiber optic networks.

Microwave networks, particularly those above 23 GHz, can suffer some degradation due to rain fade or fog, but most modern microwave manufacturers incorporate adaptive modulation schemes so that when such conditions occur, the throughput is squelched down some, rather than the link going down completely.

Microwave Fixed Wireless is as Fast as Fiber Networks
Most businesses are looking to subscribe to an Internet connection in the 20Mbps to 500Mbps range, and beyond. Microwave fixed wireless can easily achieve these speeds, even into the 1 Gbps + range (i.e. GigE), with higher reliability than fiber-optic networks. Technically, fiber has unlimited bandwidth, but as with most technologies, is limited by the electronics that are driving it.

Installation time
Having leased lines or new fiber equipment installed can be a time-consuming venture. Obtaining permits, rights-of-way, etc. are time consuming, not to mention the construction process itself, which is often disruptive of city roads, businesses, etc. Alternatively, unlicensed or light-licensed microwave links can be procured and installed within 4-5 days, and 4-6 weeks for licensed microwave.

Dependability
Fiber and leased lines are not infallible. Businesses typically turn to fixed wireless Internet solutions after losing their fiber data connections due to a number of reasons. Some also install microwave as a backup/redundancy to fiber to manage the risk of communication loss and minimize downtime.

Cost
The ROI with a wireless network, as opposed to fiber-optic, can be achieved in months instead of years. The cost of installing dark fiber in a metropolitan area, or even rural, can be exorbitant for factors previously mentioned. Not to mention the cost of repair and maintenance. With leased lines there is no ROI per se, as it is a fixed monthly cost.

Point-to-multipoint (PMP) wireless links are deployed between locations where the client wireless devices are in line-of-sight (LOS) or near line-of-sight (nLOS), with the device acting as the base station. In a PMP wireless network that works using the license free 5 GHz band (for example in the 5.8 GHz or 5.4 GHz license-free bands) or using the 4.9 GHz public safety band we suggest to deploy the link in where there is LOS, because above 2.4 GHz, LOS operations provide more reliable performances. Point to multipoint networks working on frequencies around 900 MHz or in the UHF band (400 MHz) can operate reliably in nLOS conditions. However, recent advancement in technologies among the vendor community has yielded significant nLOS performance improvement in the 2.4 GHz – 5.8 GHz PMP space.

The next evolution of PMP technology is LTE. LTE (Long Term Evolution) is a wireless communication standard originally developed to provide high-speed data for mobile phones, data terminals, and other municipal and utility applications. With increasing demand for bandwidth in industrial networks, it is also being deployed as an alternative to traditional 900 MHz SCADA radio networks. LTE offers mobile telecommunication providers the ability to increase broadband wireless backhaul and allow for future expansion. The LTE specification provides downlink peak rates of 300 Mbps, uplink peak rates of 75 Mbps.

Air Interface Protocol is the technology used for the radio transmission between a base station and it’s subscriber or mobile units in a wireless network. It is the wireless counterpart of the physical layer 1 in the OSI model.

See https://en.wikipedia.org/wiki/Air_interface

A Radio Frequency (RF) Study is a feasibility study typically used in the design of one or more microwave radio networks. This is typical done in two phases: preliminary frequency path analysis and an on-site radio frequency survey.

The frequency path analysis is typically performed via a program such as Pathloss or similar for computer-generated path profiles. This program performs automated linking and design features for point-to-point radio links. This includes the design sections for terrain data, antenna heights, diffraction, transmission analysis and reflections/multi-path analysis. The receiver threshold degradation and the resulting increase in the outage probability is then determined taking into account the fade correlation for rain and multi-path fades.

The on-site radio frequency survey (or radio feasibility study) takes the results of the frequency path analysis and tests them at the actual sites. This will ensure that the designed is accurate and will work. Aside from rooftops or towers, bucket trucks or man lifts may be utilized to simulate the heights needed that the path analysis states. Pictures are taken and visual line of sights are confirmed. The path will be driven to confirm structures, trees, and terrain in the path. RF spectrum analyzers, or in some cases demo links, are utilized to examine various frequencies and noise floors.

Beamforming is a signal processing technique used to control the directionality of the transmission and reception of radio signals. It is considered an important companion to 4×4 Multiple Input Multiple Output (MIMO) technology for Wi-Fi wireless networking. When it is included, it enables dramatic improvement in Wi-Fi 802.11ac/n performance, reliability, range and coverage.

See https://en.wikipedia.org/wiki/Beamforming

A Fresnel zone refers to the elliptical path on which a radio wave travels. Calculating the Fresnel clearance simply refers to determining the path for radio waves, while taking into account straight lines, elliptical patterns, and reflective surfaces, interference and obstacles in the path of the radio beam.

For a more in-depth explanation see https://en.wikipedia.org/wiki/Fresnel_zone

Point-to-Multipoint (also called star topology, PMP, or PTMP) is a common network architecture for outdoor wireless networks to connect multiple locations to one single central location. In a point-to-multipoint wireless Ethernet network, all remote locations do not communicate directly with each other but have a single connection towards the center of the star network where one or more base station is typically located.

The remote locations at the edge of the networks are typically called  “subscribers” or “client” locations, and the central location is called the “access point” or “base station”. Most outdoor point-to-multipoint networks implement a centralized medium access control protocol or employ a TDMA-based (time division multiple access) protocol synchronizing all radio devices with a GPS device.

Carrier Grade v. Enterprise Grade v. Consumer Grade Power & Cabling

Wireless systems can be designed and installed with differing levels of reliability and performance. Power system and cabling can vary from consumer grade to carrier grade. What does this mean?

Consumer Grade – the wireless link is installed with just enough attention to detail to “get it working” without regard to how well it holds up in weather conditions such as high winds, storms, rain or environmental conditions such as UltraViolet rays from the sun, other users stepping on cables, or bumping the antennas. In some cases this is enough, such as in temporary systems or in systems where there is no budget to do anything better. An example is a power supply that may be plugged into power and left to dangle by its power cord or cable laid on a roof or hung on a tower with no protection from being stepped on or vibrating in the wind.

Enterprise Grade – An enterprise grade power system may be a rugged power supply designed to withstand a normal temperature range plugged into a UPS, the UPS may be sized to power the radio for 15 to 45 minutes in event of a power failure. Sometimes each radio has it’s own lightweight power supply plugged into a surge power strip that is plugged into a battery backup system. The power system may have a fuse to protect the load in event of an issue with cabling or electronics.

There’s no warning or indication when the AC power fails, unless the UPS has some kind of monitoring, no reserve power and a trip to the site is usually required to diagnose the problem and a second trip is sometimes required when the problem is diagnosed and the replacement parts are procured.

Enterprise cabling usually has the cables attached to the tower with UV rated cable ties or placed across a roof on sleepers to keep the cables above standing water but not protected from sun or accidentally footprints. Cable penetrations into elevator penthouses or from outdoors to indoors may simply be a hole drilled through the wall sealed with silicone seal and a drip loop on the cable. Lighting protection may be an economical device that acts like a fuse to protect the equipment, the equipment is protected in event of a lightning event, but a re-trip and replacement may be required.

Usually an Enterprise Grade system is enough, particularly if the systems are not mission-critical and are easily accessible where truck rolls to diagnose and repair are not expensive.

Carrier Grade – Carrier Grade power systems usually an industrial grade power inverter and a battery system designed for existing and projected future loads with backup power to keep a system running for 8 to 24 hours. The power system will have redundant power supplies that fail over automatically and provide notification when they do. The system will have SNMP monitoring that will connect to some kind of network management & monitoring system that will notify key people in event of primary power failure. The SNMP system will monitor the health of the battery system, status of connections and loads and support reporting and trending reports. In some cases the carrier grade system will include environmental and security monitoring including temperature ranges both indoors and outdoors, water detection, motion and door lock sensors, air quality and other sensors may be tied into the system.

Carrier Grade cable systems reduce the long term costs of the system by reducing re-trips and maintenance. Multi-conductor cables are installed to a breakout near the antenna to make it easy to install additional systems and additional capacity without the expense of re-cabling a tower with new cables and hangers. Data interfaces are sometimes converted to fiber to eliminate the chances of power surges from lightning or other sources disabling sensitive Ethernet interfaces. Surge protectors designed to react quickly to electrical events that will take multiple hits without failing. Building penetrations may have multiple ports for future cable and a watertight seal. Surge protection may be installed at both ends of cables to protect both radios and indoor equipment. Extra attention is applied to bonding and grounding to divert any surge currents away from radios or cables.

SNMP & Remote monitoring

SNMP (Simple Network Management Protocol) is a method used to remotely monitor and manage devices on a network. In it’s simplest terms, SNMP can be configured to send a message whenever an event (called a “trap”) happens to the device, such as the temperature outside of a predetermined range, or the power supply voltage drops below a specified level.

These events are usually sent to a NMS (Network Management System) were status of the events is tracked and notifications are sent to responsible parties via text messages, pages, e-mails or other means.

More advanced configurations involve trending; tracking changes over time. Parameters such as temperature, power supply voltages and error rates. Tracking over time enables early diagnosis of potential problems and some warning of changes that may affect the reliability of the system. A range of acceptable levels is defined and if a parameter goes outside of the range, an amber or red alert may be triggered by the NMS system.

SNMP can also be used to monitor the status of power systems and the environment, from door contacts, water detection of are conditioning failure.

If you need to connect location A to location B, this is what were refer to as a Point-To-Point system. Licensed or unlicensed technology can be used for Point-To-Point systems.  Just like a roadway, the questions to be answered include:

• Type of traffic
• Capacity of traffic
• Latency
• Reliability
• Scalability

Do I need to connect two specific locations or multiple locations to one location?  Connecting multiple locations is what we refer to as a Point-To-Multipoint system.

Outdoor point-to-multipoint (PMP) wireless solutions are very common both for wireless Internet service providers (WISPs) and for outdoor video-surveillance systems.
In outdoor wireless video-surveillance systems, each camera in the field is connected to a wireless client device and then a base station is mounted on top of a tall building and acts as the central device and coordinator of the PMP wireless network. In a point-to- multipoint wireless CCTV (closed circuit television) system, all video streams from the remote cameras are collected at this central location at the center of the PMP wireless system and then transmitted to a control room using a point-to-point (PTP) wireless or fiber backhaul.

Licensed Radio Systems

Licensed radio systems generally cost more than unlicensed systems as they are manufactured in smaller quantities. Licensed radio systems have these advantages and disadvantages:

Advantages of Licensed Systems

• Interference Protection – with licensed systems there is some degree of protection from foreign noise sources, allow the radio to perform to more optimum specifications
• Licensed system typically out-perform unlicensed systems over the same distance, noise and interference conditions or same size of RF spectrum channel, this can be due to a more advanced air-interface protocol or the fact that some licensed systems are full duplex and have a separate channel for each direction.
• Licensed systems are generally lower latency that unlicensed systems

Disadvantages of Licensed Systems

• Licensed radio systems require the system to be licensed or registered with the FCC, this can take time and money. See the details of FCC licensing here
• Licensed systems have to be relicensed if they are removed or modified
• Licensed systems can cost more

Unlicensed Radio Systems

Advantages of Unlicensed Radio Systems

• Unlicensed systems can be deployed without waiting
• There is no cost with the FCC to register or license a system
• Some unlicensed systems can move between frequencies or channels to avoid noise; sometimes this feature can be a benefit, other times this feature can cause issues.

Disadvantages of Unlicensed Radio Systems

• No protection from interference for other users or radios. You can install a wireless system and someone else can come later and install a wireless system and you have to live with the results.

New fiber installations can be a time-consuming and expensive venture. Obtaining permits, rights-of-way, etc. are time consuming, not to mention the construction process itself, which is often disruptive of city roads, businesses, etc. Aerial cable is typically less expensive than buried cable, but you still have to deal with many of the same issues.

The ROI associated with a fiber-optic network, as opposed to say wireless, is realistically years instead of months. The cost of installing dark fiber in a metropolitan area, or even rural, can be exorbitant for factors previously mentioned. Not to mention the cost of repair and maintenance.