• March 23, 2012

10 Things to Know About the Status of Asymmetrical Wireless Backhaul

Paging through the radio spectrum

The ECC held a meeting in March to further consider updating regulations to allow the use of asymmetrical links in microwave backhaul (Photo credit: blese via flickr)

Last autumn we wrote about potential plans from a microwave competitor regarding using asymmetric band plans for point to point microwave communication links. To update this topic, we have put 10 things in parentheses that you should know about the current status of asymmetrical links in wireless backhaul. Last month at an Electronic Communications Committee  SE19 (Spectrum Engineering) meeting this microwave technology subject was discussed again. (1) The proposal under consideration has been reduced in scope and (2) the regulators present still wish to see more evidence regarding the need for change before agreeing to such significant amendments.

Asymmetric Band Plan Altered
A quick reminder of what was originally requested back in the autumn of 2011; a move from channel sizes of 7, 14, 28 and 56MHz to channel sizes of 7, 14, 21, 28, 35, 42, 49 and 56MHz in order to support different granularities of channel widths in all bands from L6GHz to 42GHz. However in March these proposals were altered to reflect channel sizes of 7, 14, 28 and 56MHz (i.e., no change to existing channel sizes) and asymmetric only in the 18GHz band and above.

The national regulatory authorities stated that even the (3) revised proposal cannot be accommodated with existing planning tools so they cannot imagine asymmetric links being deployed alongside existing links in their countries. A few stated that in block allocated spectrum the owner of the spectrum may be able to implement this channelization, but Aviat Networks believes that (4) the complexity of coordinating links even in block allocated spectrum should not be underestimated.

Saving Spectrum?
Traditionally, links are planned on an equal bandwidth basis, e.g., 28MHz + 28MHz, with a constant T/R spacing throughout the band in question. This new proposal would see links of 28MHz + 7MHz and furthermore makes the claim that spectrum would be saved. Numerically speaking this arrangement would save 21MHz for each pair, but (5) saved spectrum is only of value if it is reused. In many cases the “saved” spectrum would be orphaned due to difficulties coordinating it into usable pairs.

Asymmetric Channel Plan Limits Future
In our last blog on this topic we reflected on the fact that while there is some level of asymmetry today, (6) this trend may well be balanced in the near future by cloud services and other services that involve the user uploading content. We believe that (7) committing to an asymmetric channel plan now limits the future. (8) Symmetric channel planning allows networks to dynamically adjust to changing demands. A related concern is the fact that (9) spectrum once reallocated may not be easily clawed back to create symmetric pairs in the future. While some applications are experiencing asymmetry in traffic presently, we should not forget that some traffic patterns are still symmetric and where asymmetry is a feature, (10) the scale of this phenomenon may be overstated. Indeed, a major European operator present at the SE19 meeting voiced skepticism about the need for asymmetric support.

What do you think? Will mobile traffic remain or increasingly become asymmetric? Are asymmetric microwave links needed or can they be practically deployed in existing bands? Answer our poll below and tell us. Select all answers that apply.

Ian Marshall
Regulatory Manager
Aviat Networks

  • February 21, 2012

A Timely Update on Wireless Security

A Timely Update on Wireless Security

Wireless Security Components

Traditionally, microwave networks have been unsecure—unsecure as far as any purpose-built payload encryption or secure management is concerned. Until recently, it was deemed essential only for the most confidential microwave communications of financial firms, defense agencies and government, where the law can require them. But now billions of people around the world rely on the Internet to deliver varies types of data traffic ranging from personal messages to financial transactions. This value and volume of traffic makes it an irresistible target for cyber criminals. As security measures are implemented in other parts of the network (core, access) it is fundamental to implement strong security measures in microwave networks.

Aviat Networks Strong Security suite for the Eclipse Packet Node microwave radio platform prevents the following attacks on the network:

Front door attack: Traditionally microwave networks have not encrypted their payloads. With many networks transitioning from TDM to IP not encrypting payload traffic is the equivalent “of leaving the front door unlocked.” Hackers, cyber criminals and even foreign governments could try to access the air link using methods such as the “man in the middle” to read unencrypted data streams. Aviat Networks’ solution is to implement Payload Encryption that protects all traffic over the air link including user data and Eclipse management data in the payload.

Backdoor attack: Unsecured NMS can be used to change the radio configuration, sabotage or divert traffic using network management. With Aviat Networks’ Secure Management all Eclipse Packet Node management and control commands are secured over unsecure networks.

Insider attack: Disgruntled employees or cyber criminals that have obtained inside access to the network can use this access to divert traffic or upload malware to the network. Aviat Networks implements complete AAA (Authentication, Authorization and Accounting) capability through a RADIUS server that can be used to prevent, or if happens, track and identify an inside security breach.

Covering all vulnerable areas of a microwave network, Aviat Networks’ Strong Security provides the toughest standards-compliant security protection in the market.

Eduardo Sanchez
Marketing Engineering Specialist
Aviat Networks

  • November 24, 2011

How Many Radio Options Are You Juggling?

Juggling Radio OptionsBalancing cost and performance is a tough act for most operators dealing with telecom networking, especially when it comes to equipment procurement.  Getting all the bells and whistles can sometimes result in having a lot of options to choose from.   Often times microwave users have to juggle with a variety of radio options that suit a particular site requirement, for example, having to select between low power or high power radios to meet varying distance or system throughput/gain needs.  Depending on location and licensing requirements, this may even translate into different products types for different frequency bands.  More products result in more spares to maintain in inventory, along with added support and maintenance, inevitably leading to higher costs.

To help address this challenge, Aviat recently unveiled the industry’s first universal outdoor unit (ODU) to support software- defined base and high power modes in a single ODU, with Aviat’s unique Flexible Power Mode (FPM) capability.  FPM allows operators to optimize both cost and performance, minimizing their overall total cost of ownership, by paying for the power they need only when needed.  As a result, operators can procure a single ODU for multiple locations and via a simple software licensing mechanism, remotely adjust the transmit output power to meet the needs of a particular site.  No need to spare multiple radios, nor deal with the operational burden of managing and supporting a variety of product options.

Additionally, operators can apply this flexibility to migrate from legacy low power, low capacity radios to a high power and performance ODU  to support much greater link throughput, without having to change their installed antennas. This minimizes both their CAPEX and OPEX while migrating their network from a legacy low capacity TDM microwave link to a high speed Ethernet one.

So while juggling may still be a well needed skill to survive in Telecom, Aviat is reducing the load when it comes to microwave networking. Click here to find out more.

Errol Binda
Senior Solutions Marketing Manager
Aviat Networks

  • October 18, 2011

What is Asymmetrical Link Operation?

Introduction
Last year one of our microwave competitors introduced a new development for the point-to-point licensed microwave market – asymmetrical link operation. There are some very real challenges with the growth of mobile multimedia that are driving interest in this approach. However there are numerous harsh realities involved in introducing such a ‘radical’ technique into the relatively conservative licensed microwave industry. The myriad of Regulatory studies and approvals that will be needed to enable asymmetric operation to be deployed in existing bands means that it could be years, if ever, before asymmetric links can be deployed in most countries around the world.

Today’s Licensed Microwave Bands are Exclusively Symmetric
In current licensed microwave bands and all commercially available equipment today, transmission is symmetric – i.e., the same capacity and bandwidth in both directions. Frequency bands are arranged for frequency division duplex (FDD) operation, where two identical channels are used for Tx (‘go’) and Rx (‘return’). Asymmetric operation is usually reserved for unlicensed time division duplex (TDD) radios, which use a single channel for both go and return.

Spectrum Borrowing
The proposed Asymmetrical scheme is based upon a concept called ‘Spectrum Borrowing’, where frequency spectrum is taken from the upstream direction of a lower capacity link, and given to the downstream direction of an adjacent higher capacity link.

What is Asymmetrical Link Operation?

Before - Symmetrical Microwave Network

A second (but related) proposal has been also tabled to amend the standard channel options from the current 7, 14, 28, 56 MHz to an n*7MHz arrangement (i.e. 7, 14, 21, 28, 35, 42, 49, 56 MHz), which is required to support the asymmetric concept.

What is Asymmetrical Link Operation?

Asymmetrical Microwave Network, after Spectrum Borrowing

What is driving the need for this Asymmetry?
The underlying rationale is that in 3G and 4G mobile networks, a majority of the traffic over the network is increasingly web- and video- based, meaning more capacity is needed in the backhaul network in the direction towards the base station, and less in the opposite direction back to the core.

However, while this is true today, new emerging mobile applications such as video chat, video uploading, P2P sharing, and new cloud based services (eg: iCloud), have the potential to change the imbalance between upload and download demand over the longer term. This presents a challenge for the proposed asymmetric implementation, which is fixed in nature, not dynamic. This means that the link has no way to adapt to instantaneous uplink/downlink traffic demand, or to change over time as more uplink capacity is needed. Changing this ratio could prove to be very difficult once an asymmetric link is in place and has been operating for several years.

Regulatory Approval
Making substantial changes in the way that licensed microwave bands are used is not a simple process, since strict regulations and standards at the international and national level have been put in place to ensure that links deployed in these bands are assured to be virtually interference free.

A proposal has now been submitted to the Electronic Communications Committee (ECC), the Regulatory Body responsible for amending the channel plans for the existing frequency bands, a part of the European Conference of Postal and Telecommunications Administrations (CEPT), representing 48 countries throughout Europe and Russia. The ECC has agreed to set up a study group to examine the proposal, which is due to report their finding in February 2013.

If the ECC agrees to amend the channel plans to permit asymmetric operation, which may not happen before 2015, the national regulator in each CEPT country will then have to decide whether or not to adopt the recommendations. Further lobbying will also be necessary beyond the CEPT region, for example with the FCC in the USA, to successfully influence regulatory policy in favor of Asymmetrical operation.

A Long Road to (Possible) Adoption
In summary, asymmetrical operation may be a potentially useful technique to improve the efficiency of backhaul networks and frequency utilization. However, introduction of this technique will be extremely difficult within existing congested frequency bands, and will face significant and lengthy regulatory scrutiny and approval before we will see widespread adoption.

Stuart Little
Director of Marketing

  • July 29, 2011

‘The Cloud’ and What it Means for Wireless Technology

Cloud

Image via Wikipedia

The cloud is an all-encompassing thing that’s actually been around for a while (e.g. distributed computing, Network Attached Storage). Most of it exists today in the enterprise but is being pushed to the Internet and rebranded “The Cloud.” This affects three wireless networking segments: consumers (e.g., you, me, mom, dad), Internet providers (e.g., mobile operators, ILECs, CLECs) and wireless solutions vendors (e.g., Symmetricom, Aviat Networks).

For consumers, it represents the ability to store information—pictures, music, movies—virtually and access them wherever we go from devices of our choice. No longer do we have to worry about backing up smartphones, tablets or laptops. The downside is that this magic is going on in the background all while your data caps are being reached. So, watch out….

On the mobile operator side, this will represent a substantial increase in bandwidth used. In addition, bandwidth usage starts to become more symmetrical as more uplink bandwidth is utilized while uploading to the cloud. This also means more frequency consumption on the RAN-side as subscribers stay “on” more often. Operators need to figure how to get users off the air interface as quickly as possible. This calls for greater throughput and potentially much lower latency. Trickling data to end users compounds the air interface problem. For the most part, subscribers won’t realize what’s happening and data caps are more likely to be reached. This translates into either more revenue and/or dissatisfied customers. Clearly, operators must monetize transport more effectively and at the same time provide more bandwidth.

Lastly, for wireless solutions vendors this translates into increased sales of wireless equipment to ease the sharp increase in bandwidth consumption. This also translates into more intelligent and robust network designs (e.g., physical and logical meshes, fine-grained QoS controls) as subscribers rely more on network access for day-to-day activities. As for the cloud in general and the overall effect:

  • Traffic starts to become more and more symmetrical (i.e., photos and videos automatically upload and then downloaded to all individual peer devices (e.g., your iPhone video uploads to the cloud and then syncs to your laptop and iPad)
  • Lots more bandwidth will be used. Today, content drives bandwidth demand (e.g., you open a browser and connect to a website, you launch your Facebook mobile app and upload photos). Tomorrow, those activities will happen automatically and continuously
  • Over the Air (OTA) updates to the phone are now downloaded over Wi-Fi or 3G/4G networks. Seemingly, updates are the only things that have changed, but it still amounts to about 150 MB per phone per update—another bandwidth driver
  • More prevalent use of video conferencing—low latency, sustained bandwidth demand

Therefore, the amount of bandwidth consumption will rise dramatically this September when Apple releases iOS 5 and iCloud. Android has already driven much bandwidth demand, but it’s not nearly as “sexy” as what Apple is releasing for its 220 million users—or alternately total iOS devices: iPod touch, iPad, iPhone). It’s more than just bandwidth—it’s quality, reliable bandwidth where QoS and Adaptive Modulation will play significant roles—of this, I’m certain.

At a recent TNMO event they were talking about LTE-Advanced and leveraging the cloud for virtual hard drives. Imagine, no physical hard drive in your computer. Laptops are connected via 4G wireless/5G LTE wireless to a cloud-based hard drive, equating to lots and lots of bandwidth plus stringent latency requirements….

Steve Loebrich
Director of Product and Solutions Marketing, Aviat Networks

  • July 1, 2011

Antennas: Why Size is Important for This Wireless Equipment

Antenna tower supporting several antennas. The...

Image via Wikipedia

In response to the recent FCC docket 10-153, many stakeholders proposed relaxing antennas requirements so as to allow the use of smaller antennas in certain circumstances. This is an increasingly important issue as tower rental costs can be as high as 62 percent of the total cost of ownership for a microwave solutions link. As these costs are directly related to antenna size, reducing antenna size leads to a significant reduction in the cost of ownership for microwave equipment links.

The Fixed Wireless Communications Coalition (FWCC), of which Aviat Networks is a major contributor, proposed a possible compromise that would leave Category A standards unchanged while relaxing Category B standards. The latter are less demanding than Category A, and after some further easing, might allow significantly smaller antennas. The rules should permit the use of these smaller antennas where congestion is not a problem, and require upgrades to better antennas where necessary.

A further detailed proposal from Comsearch proposed a new antenna category known as B2, which would lead to a reduction in antenna size of up to 50 percent in some frequency bands. This would be a significant cost saving for link operators.

At the present time, the industry is waiting for the FCC to deliberate on the responses to its 10-153 docket, including those on reducing antenna size.

See the briefing paper below for more information.

Ian Marshall
Regulatory Manager, Aviat Networks

Related articles
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  • Small Cell Mobile Backhaul: The LTE Capacity Shortfall (aviatnetworks.com)
  • Ireland Issues Spectrum Consultation on Wireless Communications (aviatnetworks.com)
  • Network Services from Aviat Networks’ Network Operations Center (aviatnetworks.com)
  • June 24, 2011

Mobile Security Requires More Than Secure Wireless Devices

Person with PDA handheld device.

Image via Wikipedia

When people think of mobile security, they usually think of encryption for their smartphones, tablet computers such as the BlackBerry PlayBook or other wireless devices. Or they think of a remote “wipe” capability that can render any lost device blank of any data if some unauthorized party did in fact try to enter the device illegally. These wireless solutions are all state-of-the-art thinking in the mobile security community. And many wireless equipment OEMs and third-party mobile security providers offer them.

But they only protect the data on the devices. They only protect so-called “data at rest” once it’s been downloaded onto the iPhone or iPad. They don’t speak to the need to cover “data in motion” as it is transmitted over the air. Some parts of the over the air journey are protected by infrastructure in the form of Wi-Fi and GSM. One is notoriously subject to human failing to enable security and the other has been broken for sometime. And then there is wireless security for backhaul. In this area, there has not even been an industry standard or de facto standard established. And most microwave solutions providers don’t even offer options for wireless security on the backhaul.

Fortunately, this is not the case across the board. Strong Security on the Eclipse Packet Node microwave radio platform offers three-way protection for mobile backhaul security: secure management, payload encryption and integrated RADIUS capability. Read the embedded overview document in full-screen mode for more details:

  • May 20, 2011

Ethernet OAM Meets Demands on Microwave (Wireless) Networks

Ethernet OAM (Operations, Administration and Maintenance) can help mobile network operators and other transport providers meet the ever-growing demands for increased bandwidth across the backhaul network as well as meeting the equally important demand for quality and reliability of service.

This white paper will look at how Ethernet OAM can help the evolution from TDM to Next Generation Networks (NGN), with a focus on microwave-based NGN radio networks.

  • May 13, 2011

Comprehensive Embedded Security in Microwave (Wireless) Networks

The current and ongoing migration toward IP networking on backhaul networks supports rising data volumes, which is increasing the opportunities and motivations for data and call interception. As data volumes rise in wireless networks and their associated microwave backhaul, security has become of greater concern.

This white paper presents a look at security issues, and the broad portfolio of solutions for remediating such concerns for microwave operators.

  • April 29, 2011

Synchronization Over Microwave Mobile Backhaul Networks


Synchronization is creating quite a stir in the mobile backhaul industry as operators are wrestling with a variety of synchronization technology options including Synchronous Ethernet (SyncE) and Precision Time Protocol (PTP) a.k.a. IEEE 1588v2. This paper reviews unique microwave backhaul characteristics that need to be taken into account in support of synchronization, and how each particular synch approach can be addressed.

  • April 20, 2011

Unlocking Capacity Block Through Higher Order Digital Modulation

If you are reading this post, then you probably have heard about “4G”, the 4th generation cellular network. For a cell phone user, 4G means improved data speeds that allow faster delivery of multimedia-based applications, see our previous post, What is 4G?, for more details. On the other hand, the network operator desires to spend a minimum on upgrading network infrastructure and prefers to buy a backhaul solution that supports current and near future capacity demands of a cellular network.

Thus, it is important to improve the capacity of wireless backhaul links. To increase transmission capacity, wider channel spacing can be used. However the wireless spectrum is expensive and may not be available in some countries. Using transmission in high frequency bands, such as 60 GHz and above, provides the bandwidth needed to increase capacity. However, very high radio frequencies increase the cost of radio components. In addition, 60 GHz links limit transmission range due to high absorption of radio waves by the atmosphere, making this solution somewhat cost inefficient. One efficient way of improving the capacity of a communication link is to increase the order of the digital communication modulation scheme used for transmission.

In simple terms, digital modulation is the process of mapping a group of data bits into an information symbol that gets transmitted, after up-conversion to the radio frequency (RF) of the link. The most popular digital modulation scheme used in wireless radios is known as quadrature amplitude modulation (QAM). For a given symbol rate, increasing the modulation order, or equivalently packing more bits per symbol, would be an effective way to increase the capacity of a microwave link. For example, each symbol in a 64-QAM signal represents 6 data bits, while for 256-QAM and 1024-QAM signals it represents 8 and 10 data bits, respectively. Therefore, 1024-QAM provides (theoretically) a 25 percent increase in capacity over 256-QAM and an impressive 67 percent increase in capacity compared to 64-QAM.

The price paid for achieving such an increase in capacity is more complex signal processing algorithms and stricter requirements for channel quality, e.g. higher signal-to-noise ratio (SNR) at the receiver is required. In that case, increasing the modulation order for some networks under normal operating conditions can have a diminishing return on throughput. This is due to the fact that the required SNR for an acceptable receiver performance rarely can be met.

Why this is the case? Let us briefly discuss the challenges in increasing the modulation order. Higher modulation order results in larger pool of symbols available for transmission. For example, for 64-QAM, there exists 64 symbols in a 2D grid (known as constellation points) compared to 1,024 symbols for 1024-QAM for the same grid size. Clearly, increasing the number of symbols (assuming fixed power) makes the symbols closer to each other in this 2D grid. Thus, data detection at the receiver becomes more susceptible to errors due to impairment.

In practical terms, receiver circuits are affected by thermal noise, clipping and non-linearity of power amplifiers, phase noise and many other distortions that are beyond the scope of this post. It is worth mentioning that increasing the signal power beyond some limits results in actually decreasing the received SNR since many of these distortions associated with RF circuits are dependent on the transmitted power. Rather, the way to increase the modulation order is to improve the detection schemes and build circuits that are less susceptible to power-related distortions, along with improving the correction mechanisms at the receiver for phase noise and other impairments.

At Aviat Networks, we have the expertise and knowledge to build the highest quality microwave radios that can work at cutting edge signaling schemes. We will make sure that our customers see a sizable return—not a diminishing one from increasing the modulation order. Our pledge is that microwave backhaul will always exceed the capacity requirements of our customers.

Ramy Abdallah,

Senior Signal Processing Engineer, Aviat Networks

  • April 15, 2011

White Paper-Deploying IEEE 1588v2 Synchronization over Packet Microwave Networks

Joint Application Note with Symmetricom and Aviat Networks.

Mobile Backhaul Networks are evolving to packet, driven by 4G evolution, requiring high data and video traffic and growing number of apps, users, smartphones and tablet devices. 1588v2 microwave are a perfect match for Mobile Backhaul evolution. Paper covers 1588v2 overview, unique considerations for microwave and typical deployment scenarios (multi-hop, ring).

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