Showing posts with label Fibre Optics. Show all posts
Showing posts with label Fibre Optics. Show all posts

Sunday, 18 September 2016

5G Fronthaul: Crosshaul & XHaul

I have written about Fronthaul as part of C-RAN in this blog as well as in the Small Cells blog. I am also critical of the C-RAN concept now that the Baseband Units (BBU) have become small enough to go on the cell cite. I have expressed this view openly as can be seen in my tweet below.

While I am critical of the C-RAN approach, there are many vendors and engineers & architects within these vendors who are for or against this technology. I am going to leave the benefits and drawbacks of C-RAN in light of new developments (think Moore's law) for some other day.

The above picture from my earlier post explains the concept of Fronthaul and Backhaul for anyone who may not be aware. As data speeds keep on increasing with 4G, 4.5G, 4.9G, 5G, etc. it makes much more sense to use Fiber for Fronthaul. Dark fiber would be a far better choice than a lit one.

One thing that concerned me was what happens in case of MIMO or massive MIMO in 5G. Would we need multiple Fronthaul/Fibre or just a single one would do. After having some discussions with industry colleagues, looks like a single fiber is enough.

This picture above from an NTT presentation illustrates how WDM (Wavelength Division Multiplexing) can be used to send different light wavelengths over a single fiber thereby avoiding the need to have multiple of these fibers in the fronthaul.

There are 2 different projects ongoing to define 5G Fronthaul & Backhaul.

The first of these is 5G Crosshaul. Their website says:

The 5G-Crosshaul project aims at developing a 5G integrated backhaul and fronthaul transport network enabling a flexible and software-defined reconfiguration of all networking elements in a multi-tenant and service-oriented unified management environment. The 5G-Crosshaul transport network envisioned will consist of high-capacity switches and heterogeneous transmission links (e.g., fibre or wireless optics, high-capacity copper, mmWave) interconnecting Remote Radio Heads, 5GPoAs (e.g., macro and small cells), cloud-processing units (mini data centres), and points-of-presence of the core networks of one or multiple service providers. This transport network will flexibly interconnect distributed 5G radio access and core network functions, hosted on in-network cloud nodes, through the implementation of: (i) a control infrastructure using a unified, abstract network model for control plane integration (Crosshaul Control Infrastructure, XCI); (ii) a unified data plane encompassing innovative high-capacity transmission technologies and novel deterministic-latency switch architectures (Crosshaul Packet Forwarding Element, XFE).

The second is 5G XHaul. Their website says:

5G-XHaul proposes a converged optical and wireless network solution able to flexibly connect Small Cells to the core network. Exploiting user mobility, our solution allows the dynamic allocation of network resources to predicted and actual hotspots. To support these novel concepts, we will develop:
  • Dynamically programmable, high capacity, low latency, point-to-multipoint mm-Wave transceivers, cooperating with Sub-6 GHz systems;
  • A Time Shared Optical Network offering elastic and fine granular bandwidth allocation, cooperating with advanced passive optical networks;
  • A software-defined cognitive control plane, able to forecast traffic demand in time and space, and the ability to reconfigure network components.
The well balanced 5G-XHaul consortium of industrial and research partners with unique expertise and skills across the constituent domains of communication systems and networks will create impact through:
  • Developing novel converged optical/wireless architectures and network management algorithms for mobile scenarios;
  • Introduce advanced mm-Wave and optical transceivers and control functions;
  • Support the development of international standards through technical and technoeconomic contributions.
The differences are summarised in the document below:

It remains to be seen if C-RAN will play a big role in 5G. If yes how much of Crosshaul and XHaul will help.

Further reading:

Sunday, 20 November 2011

Do we need Fiber?

Click on the image to view full size

From a presentation by Acreo, available here.

Monday, 8 August 2011

Radio-over-Fiber (RoF): The existing alternative to Femtocells

Recently while going through NTT Docomo Technical Journal, I came across an article on Radio over Fibre. This is the first time I have come across RoF but apparently this is a common way to provide indoor coverage before Femtocells.
My intention here is not to compare this with Femtocells as I can think of advantages and disadvantages of both of them.

I found the following extract in the book Femtocells: Technologies and Deployment:

Active Fibre DAS (Radio over Fibre)

Active fibre DAS is the most efficient in term of performance. Optical fibres are used to make the link between the MU and the RU. They can cover very long distances (up to 6 km) and support multiple radio services. With such a system the RU directly converts the optical signal into radio signal and vice versa. The other advantage is that optical fibre is very cheap and easy to install. Radio over fibre is now the most common technique used for indoor radio coverage. As detailed in [16], radio over fibre is today the optimal solution to extending indoor coverage, because it provides scalability, flexibility, easy expandability, and also because the signal degradation is very low compared with DAS using standard connections.

The following is from Wikipedia:

Radio over Fiber (RoF) refers to a technology whereby light is modulated by a radio signal and transmitted over an optical fiber link to facilitate wireless access. Although radio transmission over fiber is used for multiple purposes, such as in cable television (CATV) networks and in satellite base stations, the term RoF is usually applied when this is done for wireless access.

In RoF systems, wireless signals are transported in optical form between a central station and a set of base stations before being radiated through the air. Each base station is adapted to communicate over a radio link with at least one user's mobile station located within the radio range of said base station.

RoF transmission systems are usually classified into two main categories (RF-over-Fiber ; IF-over-Fiber) depending on the frequency range of the radio signal to be transported.

a) In RF-over-Fiber architecture, a data-carrying RF (Radio Frequency) signal with a high frequency (usually greater than 10 GHz) is imposed on a lightwave signal before being transported over the optical link. Therefore, wireless signals are optically distributed to base stations directly at high frequencies and converted to from optical to electrical domain at the base stations before being amplified and radiated by an antenna. As a result, no frequency up/down conversion is required at the various base station, thereby resulting in simple and rather cost-effective implementation is enabled at the base stations.

b) In IF-over-Fiber architecture, an IF (Intermediate Frequency) radio signal with a lower frequency (less than 10 GHz) is used for modulating light before being transported over the optical link. Therefore, wireless signals are transported at intermediate frequency over the optical.

Access to dead zones

An important application of RoF is its use to provide wireless coverage in the area where wireless backhaul link is not possible. These zones can be areas inside a structure such as a tunnel, areas behind buildings, Mountainous places or secluded areas such a jungle.

FTTA (Fiber to the Antenna)

By using an optical connection directly to the antenna, the equipment vendor can gain several advantages like low line losses, immunity to lightening strikes/electric discharges and reduced complexity of base station by attaching light weight Optical-to-Electrical (O/E) converter directly to antenna.

Thursday, 12 August 2010

AT&T on their LTE Backhaul Architecture

Backhaul is a topic that may be giving some operators nightmare. Picked up this slightly old article from Light reading via WirelessMoves.

AT&T network architect Yiannis Argyropoulos addressed the Backhaul Strategies and Core Convergence for Mobile Operators event in New York City and had the following to say:

The lines between wireless and wireline networks are blurring, as are the boundaries between access and core networks, driven by the need to carry the flood of wireless data traffic more efficiently. AT&T is aggressively deploying fiber to its mobile cell sites and migrating from Sonet to Ethernet, but more changes will be needed. AT&T started its fiber push in 2008, and it will take at least seven years to complete, said Argyropoulos.

For the short term, today's metro Ethernet architecture will support LTE, but longer term, the network architecture needs to have less operational complexity, noted the AT&T man. The carrier is in the process of testing new approaches, based in part on work being done by 3rd Generation Partnership Project (3GPP) and the Broadband Forum .

AT&T also is looking for coordination of policy control between its wireline and wireless networks, so that the core network services are the same for end-users, regardless of how they connect to the network. It is no longer adequate for quality-of-service to be delivered piecemeal, within different segments of the network, Argyropoulos stated: "There is a lot of work going on right now to harmonize these."

The early 3GPP scheme for QoS on 3G UMTS networks was too complicated to be implemented, but newer LTE QoS plans from the 3GPP, with nine QoS classes and a smaller number of individual class attributes, look more practical.

The growing volume of data traffic is having an impact on other areas of the carrier's operations, too. The widespread use of bandwidth-hungry smartphone devices is creating new traffic patterns that, among other things, eliminate traditional maintenance windows traditionally scheduled in the early hours of weekend mornings, Argyropoulos pointed out.

"Data traffic peaks at the same time as voice, but it has multiple peaks, and it doesn't ever really subside," he said. That, in turn, is putting pressure on wireless network operators and their vendors to do hitless network upgrades and to build more resiliency into their networks.

AT&T is looking to other means of offloading traffic, including routing optimization that will use gateways strategically placed in the network to direct traffic onto the Internet, and not carry it through the metro and core networks first.

"Most of the mobile data traffic is coming from the Internet and going to the Internet."

It will also be important to offload subscriber traffic generated in the home onto a domestic Internet connection, he added.

To get an Idea of the mobile backhaul load, see my earlier post here.

Along with Fiber, Microwave is also an option and you can read more about it in Daily Wireless blog.

Also came across this blod dedicated to mobile backhaul, that is available here.

Tuesday, 8 September 2009

Improved LTE backhaul via Alcatel-Lucent's 10G GPON

“The PON vendor landscape got interesting in the fourth quarter of 2008, with Alcatel-Lucent, Motorola, and Tellabs each grabbing 10% of worldwide revenue share, behind perennial leader Mitsubishi and the now number-two player, Fiberhome. In the fast-growing GPON segment, front-runner Alcatel-Lucent is being seriously challenged by Motorola, which increased its quarterly GPON revenue share 5 points in 4Q08. Meanwhile, the EPON segment, long dominated by Mitsubishi and Hitachi, is seeing some action as Sumitomo, Fiberhome, and Dasan Networks all moved up.” - Jeff Heynen, Directing Analyst, Broadband and Video, Infonetics Research

I have blogged a bit about GPON and Backhaul before. Click on the links if you havent seen the posts before.

During this year's Broadband World Forum Europe, Alcatel-Lucent not only shows that it masters next-generation wireline and wireless access. The company also highlights that Long Term Evolution (LTE) and next-generation passive optical networking (PON) technologies converge seamlessly for a smooth delivery of the most demanding, high-speed broadband services.

The live demonstration in Alcatel-Lucent's Paris demo center shows LTE's capability to deal with multiple concurrent video streams and fast channel change - and is complemented by a high-capacity 10G GPON backhaul solution for future-safe backhaul via fiber.

Alcatel-Lucent is at the forefront of developing cutting-edge technologies long before they are standardized. Even though the 10G GPON standards are still being ratified, Alcatel-Lucent shows it is ready - when needed - to meet the request for higher capacities in its customers' access networks.

Alcatel-Lucent is engaged in over 95 FTTH projects around the world, over 80 of which are with GPON (as-of Q2, 2009). In Gartner's latest FTTH Magic Quadrant assessment, Alcatel-Lucent was positioned in the leaders quadrant for the fiber-to-the-home space.

Alcatel-Lucent is also opening up details of its optical management and control interfaces (OMCIs) in a bid to help create a true multi-vendor gigabit passive optical networking (GPON) infrastructure.

Announced at this year's Broadband World Forum Europe in Paris, the first version of the OMCI Interoperability Implementer's Guide is aimed at helping other optical network terminal vendors integrate their hardware with Alcatel-Lucent's.

Tuesday, 17 March 2009

IPHOBAC's advanced photonic technologies: Up to 12.5 Gbit/s @ 60 GHz

With much of the mobile world yet to migrate to 3G mobile communications, let alone 4G, European researchers are already working on a new technology able to deliver data wirelessly up to 12.5Gb/s.

The technology – known as ‘millimetre (mm)-wave’ or microwave photonics – has commercial applications not just in telecommunications (access and in-house networks) but also in instrumentation, radar, security, radio astronomy and other fields.

Despite the quantum leap in performance made possible by combining the latest radio and optics technologies to produce mm-wave components, it will probably only be a few years before there are real benefits for the average EU citizen.

This is thanks to research and development work being done by the EU-funded project IPHOBAC, which brings together partners from both academia and industry with the aim of developing a new class of components and systems for mm-wave applications.

The mm-wave band is the extremely high frequency part of the radio spectrum, from 30 to 300 gigahertz (GHz), and it gets it name from having a wavelength of one to 10mm. Until now, the band has been largely undeveloped, so the new technology makes available for exploitation more of the scarce and much-in-demand spectrum.

It recently unveiled a tiny component, a transmitter able to transmit a continuous signal not only through the entire mm-wave band but beyond. Its full range is 30 to 325GHz and even higher frequency operation is now under investigation. The first component worldwide able to deliver that range of performance, it will be used in both communications and radar systems. Other components developed by the project include 110GHz modulators, 110GHz photodetectors, 300GHz dual-mode lasers, 60GHz mode-locked lasers, and 60GHz transceivers.

Project coordinator Andreas Stöhr says millimetre-wave photonics is a truly disruptive technology for high frequency applications. “It offers unique capabilities such as ultra-wide tunability and low-phase noise which are not possible with competing technologies, such as electronics,” he says.

What this will mean in practical terms is not only ultra-fast wireless data transfer over telecommunications networks, but also a whole range of new applications.

One of these, a 60GHz Photonic Wireless System, was demonstrated at the ICT 2008 exhibition in Lyon and was voted into the Top Ten Best exhibits. The system allows wireless connectivity in full high definition (HD) between devices in the home, such as a set-top box, TV, PC, and mobile devices. It is the first home area network to demonstrate the speeds necessary for full wireless HD of up to 3Gb/s.

The system can also be used to provide multi-camera coverage of live events in HD. “There is no time to compress the signal as the director needs to see live feed from every camera to decide which picture to use, and ours is the only technology which can deliver fast enough data rates to transmit uncompressed HD video/audio signals,” says Stöhr.

The same technology has been demonstrated for access telecom networks and has delivered world record data rates of up to 12.5Gb/s over short- to medium-range wireless spans, or 1500 times the speed of upcoming 4G mobile networks.

One way in which the technology can be deployed in the relatively short term, according to Stöhr, is wirelessly supporting very fast broadband to remote areas. “You can have your fibre in the ground delivering 10Gb/s but we can deliver this by air to remote areas where there is no fibre or to bridge gaps in fibre networks,” he says.

The project is also developing systems for space applications, working with the European Space Agency. Stöhr said he could not reveal details as this has not yet been made public, save to say the systems will operate in the 100GHz band and are needed immediately.

There are various ongoing co-operation projects with industry to commercialise the components and systems, and some components are already at a pre-commercial stage and are being sold in limited numbers. There are also ongoing talks with some of the biggest names in telecommunications, including Siemens, Ericsson, Thales Communications and Malaysia Telecom.

“In just a few years time everybody will be able to see the results of the IPHOBAC project in telecommunications, in the home, in radio astronomy and in space. It is a completely new technology which will be used in many applications even medical ones where mm-wave devices to detect skin cancer are under investigation,” says Stöhr.

You can see their demo here.

Sunday, 7 October 2007

The GPON Standard

Towards the end of 2008, HSDPA+ will offer up to 28mbps download and 5,8mbps upload speeds, and in the second half of 2009, HSDPA++ will offer 42 mbps download and 12 mbps upload speeds. In the same year long-tern evolution (LTE) technology will push mobile data throughput to 100 mbps download and 50 mbps upload speeds and take the networks from 3G to 4G technology.
Another broadband technology in the pipeline is Gigabit Passive Optical Networks (GPON), which will provide high-speed fibre cable to the home at 100 mbps over distances up to 20km, and will be available in two to three years time. Unfortunately with so many technologies in evolution it is difficult to kep track of all the new things happening in Telecom world but here is my attempt to explore these new technologies.
In April Freescale made the following press release:
The delivery of rich digital content to the home and small office via fiber takes a major step toward reality today with the introduction of the MSC7120 from Freescale Semiconductor – the industry’s first voice-enabled Gigabit Passive Optical Networking (GPON) SoC.

The multi-core MSC7120 integrates a Power Architecture™ CPU, a StarCore™ DSP and a data path engine to deliver a complete PON sub-system in a single device. It addresses the high data forwarding throughput requirements of several applications including the delivery of “triple play” (voice, video and data) broadband services to the home or small business.
GPON technology supports the convergence of IP over optical networks, offering connection speeds much higher than today’s DSL- or DOCSIS-based networks. It is a key enabler for bandwidth-hungry “triple play” applications such as HDTV and Video on Demand.

Analyst firm IDC forecasts that worldwide consumer and small business broadband subscriptions will grow to approximately 400M subscriptions by 2010.

As the number of broadband subscribers worldwide expands, GPON is recognized as an emerging solution to challenges that threaten to constrict delivery of rich content to end consumers over “last mile” infrastructure.

“Over the next few years, GPON technology will become a viable solution for increasing bandwidth in today's access networks, especially as carriers address the increasing demand for video as a key element of their ‘triple play’ services,” said Aileen Arcilla, senior research analyst at IDC.
Wikipedia has good introduction on PON standards:
Early work on efficient fiber to the home architectures was done in the 1990s by the Full Service Access Network (FSAN) working group, formed by major telecommunications service providers and system vendors. The International Telecommunications Union (ITU) did further work, and has since standardized on two generations of PON. The older ITU-T G.983 standard is based on asynchronous transfer mode (ATM), and has therefore been referred to as APON (ATM PON). Further improvements to the original APON standard – as well as the gradual falling out of favor of ATM as a protocol – led to the full, final version of ITU-T G.983 being referred to more often as broadband PON, or BPON. A typical APON/BPON provides 622 megabits per second (Mbit/s) of downstream bandwidth and 155 Mbit/s of upstream traffic, although the standard accommodates higher rates.

The ITU-T G.984 (GPON) standard represents a boost in both the total bandwidth and bandwidth efficiency through the use of larger, variable-length packets. Again, the standards permit several choices of bit rate, but the industry has converged on 2,488 Mbits per second (Mbit/s) of downstream bandwidth, and 1,244 Mbit/s of upstream bandwidth. GPON Encapsulation Method (GEM) allows very efficient packaging of user traffic, with frame segmentation to allow for higher Quality of Service (QoS) for delay-sensitive traffic such as voice and video communications.
Some Applications of GPON can be found here.