What You Need to Know About WiMAX 802.16

July 26, 2018 at 8:00 AM

 

In the IEEE’s world of standards, 802.16 is dedicated to the global deployment of broadband metropolitan area networks. The technology for this standard has been named WiMAX (Worldwide Interoperability of Microwave Access), it is used for long-rage wireless networking for mobile and fixed connections. Though not as popular as Wi-Fi or LTE, WiMAX has much to offer.

 

When compared to similar technologies, WiMAX offers low cost and increased flexibility. It is an OFDMA-based, all IP, data-centric technology ideal for use in 4G mobile. WiMAX can be installed with shorter towers and less cabling, which supports city or country-wide non-line-of-sight (NLoS) coverage. This cuts down installation time and saves on cost when compared to standard wired technology such as DSL. In addition to fixed connections, WiMAX service is offered through a subscription for access via devices with built-in technology. Currently, WiMAX is in many devices such as phones, laptops, Wi-Fi devices and USB dongles.

 

WiMAX is capable of speeds up to 40 Mbps over a distance of several miles. WiMAX can also provide more than just internet access, it can deliver video and voice transmissions and telephone access. All of these capabilities, plus lower cost and faster installation times make it an attractive option for areas where wired internet is too costly or not available. WiMAX can also be used in several other ways: as a backhaul to transfer data through an internet network, as a replacement for satellite internet for fixed wireless broadband access and for mobile internet access comparable to LTE.

 

After many revisions, WiMAX has now evolved into its most current version: WiMAX Advanced, which is backwards-compatible with previous versions (WiMAX Release 1.0 and 2.0). WiMAX Advanced utilizes all of the same capabilities while providing 100 Mbps mobile speeds and 1 Gbps fixed station speeds. Plus, WiMAX Advanced supports additional devices and broadband wireless access technologies, MIMO, beamforming and radio access technologies for operation within a multi radio access network. WiMAX is managed by the WiMAX forum, a non-profit group that certifies and endorses wireless products that are compatible with the 802.16 standard, these include WiMAX Advanced, AeroMACS and WiGRID.

 

Of course, there are drawbacks to WiMAX, speeds can get slower as the source gets further away. Also, when multiple users are connected at the same time, performance can suffer. WiMAX might never be as popular as Wi-Fi, but there are plenty of benefits that make it a good option to consider.

 

A Closer Look at PIM

January 14, 2016 at 8:00 AM

 

We’re not talking about a Personal Information Manager (PIM), or Product Information Management (PIM) or the delicious gin-based British beverage – that’s Pimm’s. The PIM we’re talking about is Passive Intermodulation, which may sound imposing, but here we’ll break it down for you.

 

What it is:

Passive Intermodulation (PIM) is a type of signal interference in a wireless system. PIM can be a problem in almost any wireless network but it can really wreak havoc on distributed antenna system (DAS) and LTE networks. DAS networks are used to distribute cellular and Wi-Fi signals throughout a building or area, and LTE networks support high-speed wireless access for mobile phones, tablets and other mobile wireless devices. With both of these technologies supporting many of our wireless devices, it has become increasingly important to detect and lessen PIM’s effects.

 

Why it happens:

PIM is caused by nonlinearities in the passive mechanical components of a wireless system such as antennas, cables and connectors, especially in places where two different metals come together. As nonlinearities increase, so do PIM signals. PIM in the transmission path degrades the quality of the wireless communication system. Damaged RF equipment or even nearby metal objects such as guy wires and anchors, roof flashing and pipes can also be sources of PIM.

 

Additionally, PIM can be caused by two or more carriers sharing the same downlink path in a wireless network. This practice is becoming more common as wireless networks become increasingly complex with multiple technologies and technology generations at a single site. When two signals combine, it causes signal interference and can significantly impact the performance of DAS and LTE networks.

 

How it's measured:

PIM is measured in decibels relative to the carrier (dBc) or decibel-milliwatts (dBm).  Levels near -100 dBm or less are generally considered good, but the lower the better.  Tests have shown that when PIM levels were increased from -125 dBm to -105 dBm there was an 18% drop in download speeds, even though 105 dBm can be considered an acceptable PIM level.


How to protect your network:

Individual components are often tested for PIM during the design and production processes to make sure that they aren’t significant PIM sources once they’re installed. In the case of a DAS, sometimes the entire system is tested for PIM as well as the individual components. Installation also plays a critical role because proper connections are necessary to keep PIM levels to a minimum.

 

PIM is also assessed during the cellular site placement process. Ideally, this happens before the cell site and antennas are positioned as well as during the installation process.

 

Plus, an increasing amount of test companies are offering specialized equipment to detect, pinpoint and address PIM sources. There are also low-PIM rated products now available to help keep PIM at bay. 

 

PIM-certified equipment is becoming more common. For example, antennas may be PIM-certified to a level of -140 dBm and those requirements are becoming increasingly strict.

With so many devices dependent on strong wireless signals, PIM could definitely throw a wrench in the system.  Fortunately, there are steps that can be taken to identify and prevent the adverse effects of PIM. 

 

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