Sunday, 20 November 2011
Monday, 8 August 2011
I found the following extract in the book Femtocells: Technologies and Deployment:
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
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
“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
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.
Sunday, 7 October 2007
â€œOver 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 â€˜triple playâ€™ services,â€ said Aileen Arcilla, senior research analyst at IDC.
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.