Is your network PhaseReady?

attend the Phase Ready Seminar from Chronos

Phase Ready?

As you think about the evolution of your network, don't limit your thoughts to the frequency stability you need now. We want to help ensure that network roll-outs today will still be relevant come the explosion of HetNets and Small Cells.

Scandinavian PhaseReady Seminars

Scandinavian PhaseReady Seminars

Supporting phase at the edge of your network is not just a technological challenge. Employing the right technologies in the right places - from the core to the edge of your network – is essential to ensure an available and economically supportable phase delivery network. Chronos' experienced team can ensure that network infrastructure is fit for phase and deliver the tools and services necessary for you to deliver phase wherever and whenever you need it.

Chronos is hosting PhaseReady 2015 events "Supporting your Network Phase" in Stockholm on Tuesday 17 November and Copenhagen on Thursday 19 November 2015.

Join experts from Chronos, Microsemi and Transmode at these free events to assist you with your phase challenges.  Agenda topics include “Delivering Resilient Phase Synchronisation in Transport Networks” and “Phase Synchronisation and Beyond”.

REGISTRATION

Continue reading
1701 Hits
0 Comments

Donut or Doughnut - the wrong question?

Back in March I blogged asking whether you (well your phase delivery network actually) were a donut or doughnut person. The donut would be a ring of PRTCs (Primary Reference Time Clocks) at the edge of your network access layer delivering phase to Gateway devices and eNodeBs.The doughnut would have resilient (perhaps Caesium supported) PRTCs in your network core. The terms of this question were really about a battle of technologies as well as network architecture. I've since realised that this question is really not valid for a reliable supportable phase delivery network for TDD and LTE-A services that you are now on the verge of rolling out.

For me most of the technology issues are resolved (microwave links delivering phase being the most challenging), although implementations will vary wildly and standards have yet to catch up with real world network issues.

I think the key requirement for a phase delivery network is not the timing technology that underlines it but what happens when things fail! For example GPS directly connected at the eNodeB or Cell Site Gateway should easily deliver 1.5us at the air interface, but for how long will it continue to meet this requirement if some kind soul cuts through the GPS cable? Will it be long enough for your field force to get to site and effect a repair before the timing requirement is breached at an economic cost?

With this in mind I believe that the ideal phase implementation may well be a donut supported by a doughnut! I also believe this will be best delivered by an phase system independent of the network equipment. With PRTCs at the donut layer supported by PRTCs in the doughnut; especially if supported by Caesium in the core and Automatic Path Asymmetry Compensation (as implemented in the TimeProvider 2700) at the donut layer; next day mobilisation of field force could still allow fixes before the network edge breaks the 1.5us barrier.

Continue reading
2333 Hits
0 Comments

Chronos Technology and Semtech form partnership to deliver managed, PhaseReady™ network edge monitoring & timing solutions

Dramatically reducing the cost of supporting time-alignment in wireless networks including TDD and LTE-A                                                   

Chronos Technology, a global expert in time, timing, phase and monitoring systems, and Semtech Corporation (Nasdaq: SMTC), a leading supplier of analogue and mixed-signal semiconductors, are pleased to announce that they have developed a range of managed solutions which will reduce the transition to time or phase alignment in today’s advanced wireless networks where technologies such as LTE TDD and LTE-A will require more than just simple frequency alignment.

IEEE 1588-2008 Precision Time Protocol (PTP) has become well established as the leading technology for providing frequency, phase and time-of-day synchronisation over packet-based networks. However, deploying PTP-capable equipment in legacy networks can be highly disruptive and a prohibitively expensive upgrade in many cases. The range of managed solutions from the Chronos/Semtech partnership will address this issue enabling accurate delivery of time/phase, protect from GPS vulnerabilities and allow network monitoring. More>>

 

Continue reading
2524 Hits
0 Comments

Edge Microwave - Transparent or Boundary Clock?

We've been fortunate enough at Chronos to work with several microwave equipment manufacturers in the last year or so, helping them develop and test their implementations of On Path Support for Edge Phase applications. We have seen some quite astonishing improvements in Packet Delay Variation (PDV) of PTP packets when implementing a Transparent Clock; actually in turning the radio link in to a virtual Transparent Clock.

All the manufacturers we have spoken to (of course this is not ALL manufacturers!) are implementing a version of this Transparent Clock. They have come to this conclusion independently, I think because they realise that the many variations that the radio link can encounter due to loading, bandwidth use, scheduling, weather or other external factors means that simply terminating the PTP flow at the link "Ingress" and generating a fresh flow at the "Egress" will not deliver the standard of output clock needed to support a living and breathing network.

I was surprised therefore when I discovered that manufacturers were under external pressure to deliver Boundary Clock rather than Transparent Clock. The main two reasons seem to be that use of Boundary Clock for Phase is now standardised whereas Transparent Clock is not, and that Transparent Clock breaks OSI Layer boundaries.

We are actually beginning some tests in the next week or so to start to characterise some microwave links' PDV and their effect on Boundary Clock performance. In my opinion the fact the the standards bodies can't keep up with technology should not be a brake on development, and is no surprise to any of us in any case! The Layer Violation argument seems a bolt on excuse to me - if the manufacturers believe Transparent Clock is the best way to deliver On Path Support then we should get on with supporting them in the standards!

A poorly working compromise will simply not do in the urban Small Cells space. We're in a different world now and what works should be what is implemented.

Continue reading
2953 Hits
0 Comments

Small Cells Summit Roundup

Continue reading
1970 Hits
0 Comments

Small Cells World Summit - sync is creeping on to the agenda!

Had the pleasure of contributing to a panel discussion at the Small Cells Backhaul Summit at the ExCeL last week. We had half an hour on the topic "Time and timing distribution for small cells". My co-panellists were Martin Kingston, Principal Designer at EE and Richard Strike, Business Development Manager, Ethernet Access at ADVA Optical Networking; and it was ably moderated by Rami Yaron. The discussion really centred on getting phase to the edge of mobile networks, and how the business case stacks up to achieve this.

Now half an hour doesn't seem like much, and in fact the discussion could have gone on for a LOT longer, but it is half an hour more than last year's event! There were a lot of presentations in the Backhaul Summit that mentioned to various degrees how difficult getting phase to the network edge is going to be, but no real expansion on that at all.

I was pleased that my view of the world chimed pretty well with Martin's; I've known him for many years now and respect his judgement and so if we are in accord I know I'm doing something right! Interestingly the area where we parted company was an unexpected one for me. I've thought that Small Cells would be more expendable than Macro Cells, and that operators could probably stand availability levels less than the five-nines we're used to in the Core. Martin was quite clear that if it is on his network it needs to be available! This will have quite an impact on timing and backhaul technologies; and pose some interesting questions for Small Cell holdover capability.

Continue reading
2972 Hits
0 Comments

Donut or Doughnut? Where will your Phase come from?

I've spent a lot of time since the beginning of the year talking to carriers and equipment vendors about the problems using PTP to get phase sync to the edge of networks. This includes talking to both the carrier and vendor about a network that is being installed this year and will need edge phase sync down the line. I've also spoken to two mobile carriers with very different philosophies of likely network rollout to achieve adequate phase sync, and another operator planning a network for rollout in a couple of years still to make such choices.

The fundamental choice seems to boil down to this - are you a donut or doughnut person? In much of the world a donut has a ring shape - hollow in the centre (center if we're following the spelling of donut!). Many believe they can deliver phase sync from "the edge of the core" or access layer. This would involve a layer of GPS PRTC / Boundary Clocks a minimal number of hops from the network edge - a phase sync "donut".

Here in the UK a doughnut is a disc shaped confection with no hole but a large amount of jam (jelly?) in the middle. In this case a smaller number of larger capacity and more resilient GPS PRTC devices would be deployed in the network core; disseminating phase sync through a network path that would probably demand full PTP awareness and on-path support.

Of course many factors in your network design could tip you from the donut to the doughnut - will you be deploying in largely legacy sites or is this a "green field" project; is it planned to have some or all of your traffic carried through a third party Managed Service; will you be using third party "dumb pipes" to transport your PTP packets for at least part of their journey to the edge?

Even if your LTE-A plans are a year or two away, you need to be thinking whether you are a donut or doughnut network. We at Chronos are developing "Phase Ready" tools to help carriers make these decisions, then implement and monitor them.

Continue reading
2284 Hits
0 Comments

An Independent Sceptic?

Very early in the development of PDH and SDH networks, carriers removed the timing functions from the network elements and implemented independent systems for time and timing dissemination and management. Interesting therefore that as timing requirements for edge applications are probably more stringent and difficult to achieve than ever, a large amount of timing dissemination and management is being taken back in to the network equipment!

What does that mean for you as a carrier? If you're a "bell head" traditional transmission person its a headache; if your a "net head" then perhaps not so much so. Fundamentally though to move microsecond phase coherence to the edge of your network you will need on-path support throughout (although don't jump to the conclusion that if you have on-path support that you will necessarily be successful in meeting all applications requirements).

But how well do these transparent and boundary clocks perform? What about the network in between them, especially if it is not in your control? Will the equipment vendor continue to support and improve their clock implementations for the long term? How do you manage failure scenarios? If you are using a managed service' phase implementation, how do you monitor its performance and hold them to account?

I think we at Chronos, and specialists like us, have a role to play in developing and maintaining your phase networks going forward. We can be that independent sceptic you need; one who understands the issues, can help with phase network design, verification, dimensioning and commissioning.

I will be developing these themes in the coming weeks and months. This is the biggest change in timing networks for at least twenty years and I believe we have the expertise and tools to help you make this process as pain free as possible!

Continue reading
2504 Hits
0 Comments

Is the "Phase Ready" message getting through?

A couple of contrasting situations in big European Mobile Carriers demonstrates that the message is starting to get through - but there's still a lot of work to be done!

One major carrier who work closely with us at Chronos on sync and timing are busily engineering their edge network to be as symmetrical as possible to make sure their PTP for phase performance is a good as it can be. They currently have NO projects that require phase, although they use both SyncE and PTP for edge frequency.

I also heard this week of a carrier that committed only last year to a large rollout of Ethernet Microwave radios for backhaul, but selected a platform that cannot support PTP on path support. This is a supported product and so no criticism on selecting this for the project they had at the time, but they are now considering a trial of LTE-A requiring phase at the edge via a backhaul pipe that will impair phase performance with no upgrade path to help!

It really does make sense to think of the phase supporting future when considering frequency only projects today. This future is not as far away as you may think, and is likely to be in the lifetime of equipment you are currently considering for use.

Continue reading
1906 Hits
0 Comments

If the clock delivers, who cares about packets?

The most direct, and often least complicated, way to give visibility of whether packet timing technologies are delivering the expected synchronisation performance is to measure the produced or synthesised signals at the slave clock. Whether sync is delivered across a Carrier Ethernet, Microwave, or IP/MPLS network using IEEE 1588v2 (PTPv2) the ‘business end’ and proof of slave clock performance can be ascertained via the frequency, pulse, or time-code produced by it.

Connecting to a frequency, 1PPS or time-code output of a slave clock is often much quicker to perform and the, subsequent results simpler to analyse, than the more complicated procedures required to measure the performance or Packet Delay Variation (PDV) of an Ethernet or IP timing flow.

If the measured output performance is within specification for that part of the network, it doesn’t matter that PTPv2 packets may be occasionally dropped in the network or that the PDV sometimes strays outside the nominal quality levels because as long as the application is getting the quality of clock it requires then packet performance is of secondary importance.

Packet Delay Variation of the PTPv2 flow worries some engineers and they can, and do, invest valuable time and resources trying to unnecessarily find and solve perceived issues. From experience and sync monitoring projects, Chronos experts know that well engineered networks and PTPv2 clients will produce in-specification clock in many types of network conditions and this can be verified by monitoring the frequency, pulse or time-code from a test point. Of course if the measured clock is not within specification then investigation into the incoming flow is required but it does not need to be the first step.

Continue reading
2869 Hits
0 Comments

And You Thought Phase Would Be Tough?

I must admit that over the last year or so I thought, as far as PTP is concerned, that "frequency is done". From the early development days of PTP for frequency we went from "you can't trust it over more than 3 hops" to moving frequency through long networks of switches and microwave links without batting an eyelid. In this context the crusade to ask "Is Your Network Phase Ready?" began.

Intriguing then that I know of a situation TODAY where a Gateway device from a very reputable manufacturer with embedded PTP client is incapable of delivering adequate FREQUENCY to Node Bs after only a few network hops with even moderate traffic levels. This leads me to reinforce a view I've spoken about before - just because something is PTP aware doesn't mean it works!

We're seeing the drive today for full on path support in sync networks delivering phase to the edge, and people wanting to play in the Small Cells space (like Microwave Backhaul providers)  realise that they will have to interact with these PTP packets and will all be implementing a variety of boundary and transparent clock type solutions to do so.

I am still very much of the opinion then that your sync network should be INDEPENDENT of your transport network, or at least independently monitored and qualified for time and timing performance.

If you can't move adequate phase performance to the edge of your network you WILL have a negative impact on your customers' experience. Can you trust this key performance element to the people who supplied and support your transport network?

Continue reading
10502 Hits
0 Comments

Distributing Phase using PTP

Continue reading
6572 Hits
0 Comments

Beyond G.811? Standards Supporting Phase Requirements

Continue reading
Tags:
12017 Hits
0 Comments

Beyond G.811? Time Accuracy Requirements

Continue reading
Tags:
50749 Hits
0 Comments

Tested Against What?

There was an interesting question from the floor during our Phase Ready Seminar on Wednesday; basically questioning the need for independent benchmarking and monitoring of phase in a network when manufacturers are building in an array of synchronisation performance statistics into their PTP Aware Switches and Routers.

From our perspective the response is simple - what are these statistics actually measuring and what are they measuring against? Of course in day to day operations the data available from within the end to end network management platform will be a key to deciding what actions if any are required should a particular set of circumstances arise. However, we think that, at the very least, these performance metrics should be calibrated against a set of independently verified and traceable measurements to put them in greater context.

This is why we are working with several equipment vendors to integrate SyncWatch into their EMS and OSS systems.

Continue reading
3860 Hits
0 Comments