The Opportunities and Challenges of LTE Unlicensed in 5 GHz
David Witkowski, Executive Director, Wireless Communications Initiative
In 1998, the Federal Communications Commission established the Unlicensed National Information Infrastructure or U-NII 5 GHz bands. These are used primarily for Wi-Fi networks in homes, offices, hotels, airports, and other public spaces and also consumer devices. U-NII is also used by wireless Internet Service Providers, linking public safety radio sites, and for monitoring and critical infrastructure such as gas/oil pipelines.

MMD March 2014

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Band Reject Filter Series
Higher frequency band reject (notch) filters are designed to operate over the frequency range of .01 to 28 GHz. These filters are characterized by having the reverse properties of band pass filters and are offered in multiple topologies. Available in compact sizes.
RLC Electronics

SP6T RF Switch
JSW6-33DR+ is a medium power reflective SP6T RF switch, with reflective short on output ports in the off condition. Made using Silicon-on-Insulator process, it has very high IP3, a built-in CMOS driver and negative voltage generator.

Group Delay Equalized Bandpass Filter
Part number 2903 is a group delayed equalized elliptic type bandpass filter that has a typical 1 dB bandwidth of 94 MHz and a typical 60 dB bandwidth of 171 MHz. Insertion loss is <2 dB and group delay variation from 110 to 170 MHz is <3nsec.
KR Electronics

Absorptive Low Pass Filter
Model AF9350 is a UHF, low pass filter that covers the 10 to 500 MHz band and has an average power rating of 400W CW. It incurs a rejection of 45 dB minimum at the 750 to 3000 MHz band, and power rating of 25W CW from 501 to 5000 MHz.

LTE Band 14 Ceramic Duplexer
This high performance LTE ceramic duplexer was designed and built for use in public safety communication and commercial cellular applications. It operates in Band 14 and offers low insertion loss and high isolation to enable clear communications in the LTE network.
Networks International

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December 2013

For Wireless Carrier RF Distribution, Digital is the Real Deal
By Peter Walters, Chief Operating Officer, Dali Wireless

Liam Devlin, CEO, Plextek RF Integration

When the cellular industry began its meteoric rise in the early 1990s, the media was quick to call it the “Wireless Revolution”. With that in mind, the enormous changes that have taken place since the deployment of “4G” certainly qualify as Wireless Revolution 2.0. Compared to even a few years ago, the number of services available on a smartphone or tablet is truly incredible -- and they are available anywhere, or least anywhere there is quality high-speed data coverage. Unfortunately, this often excludes some of the places we’re most likely to be, such as offices, sporting events, and other places where many people gather. Consumers typically blame inadequate coverage for these annoyances, but the problem is more likely a lack of capacity.

This is because the sheer speed at which this revolution has occurred and the data that users generate are overwhelming the ability of wireless carriers to accommodate them. Much has been written about just how much data current high-speed data services are generating, introducing new words like zettabytes (1 trillion gigabytes) to our vocabulary. Although such astronomically high numbers don’t convey anything comprehensible to most people, they provide a pretty good idea of the extraordinary amount of traffic carriers must deal with -- and this is just the beginning. The next generation of LTE (LTE Advanced) will offer consumers speeds that are now available only via wired services like Fiber to the Premises (FttP) and cable. The result is a growing data tsunami that wireless carriers will need to continually stay ahead of.

Consequently, carriers are now using all available means to offload this traffic from their networks, including small cells and even Wi-Fi. However, distributed antenna systems (DAS) combine the ability to provide both coverage and capacity in places where RF energy cannot reach and in dense-traffic areas, while also offloading data from the overall network.

A DAS can simultaneously accommodate Wi-Fi as well as carriers’ small cells, and can accomodate all carriers serving a given area and allocate network capacity to and from specific places. However, to be viable both now and in the future, a DAS solution must first and foremost rely heavily on digital technology with transmission via optical fiber throughout the network, which provides extraordinary flexibility for expansion and reconfiguration.

As most DAS systems are either purely analog or a combination of analog and digital, they cannot reap the benefits that a purely-digital solution provides. Only when the signals remain in the digital domain from where they enter the network to where they are converted to analog for over-the-air transmission can true flexibility be achieved. Only true digital systems also allow control of every element of the network via software, including detailed monitoring, addition of new features, and “plug-n-play” configurability, to name a few.

Finally, the system must be cost-effective and this includes not just being less costly when installed but throughout its life, which will invariably include the addition of new features, changes to wireless standards, new frequency allocations, extensions if required, and maintenance. In all cases a digital system, as it can require fewer components, is inherently more reliable, and can reduce instances of “ripping and replacing” hardware to upgrade the network. In short, while most DAS systems are currently not fully digital, the enormous benefits digital systems provide will ensure that in the future they all will be.

Dali Wireless
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Uncertain Times for DefenseOpen’s Systems and Changes in DoD Procurement: This Time It’s Real
By Barry Manz

The U.S. Department of Defense has a well-earned reputation for inertia. Many proposals for change are made – but nothing happens. The COTS initiative, which promised cost savings through the use of off-the-shelf commercial parts, sounded terrific at the time. It heralded a major departure from standard DoD procurement that more or less guaranteed that every system would be different in part because it used parts that were developed from scratch, leading to “one-off” systems that were very expensive. Read More...

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