Europe gets its first TWDM-PON field trial
Vodafone is conducting what is claimed to be the first European field trial of a multi-wavelength passive optical networking system using access equipment from Alcatel-Lucent.
Source: Alcatel-Lucent
The time- and wavelength-division multiplexed passive optical network (TWDM-PON) technology being used is a next-generation access scheme that follows on from 10 gigabit GPON (XG-PON1) and 10 gigabit EPON.
“There appears to be much more 'real' interest in TWDM-PON than in 10G GPON,” says Julie Kunstler, principal analyst, components at Ovum.
The TWDM-PON standard is close to completion in the Full Service Access Network (FSAN) Group and ITU and supports up to eight wavelengths, each capable of 10 gigabit symmetrical or 10/ 2.5 gigabit asymmetrical speeds.
“You can start building hardware solutions that are fully [standard] compliant,” says Stefaan Vanhastel, director of fixed access marketing at Alcatel-Lucent.
TWDM-PON’s support for additional functionality such as dynamic wavelength management, whereby subscribers could be moved between wavelengths, is still being standardised.
The combination of time and wavelength division multiplexing, allows TWDM-PON to support multiple PONs, each sharing its capacity among 16, 32, 64 or even 128 end points depending on the operator’s chosen split ratio.
There appears to be much more 'real' interest in TWDM PON than in 10G GPON
Alcatel-Lucent first detailed its TWDM-PON technology last year. The system vendor introduced a four-wavelength TWDM-PON based on a 4-port line-card, each port supporting a 10 gigabit PON. The line card is used with Alcatel-Lucent’s 7360 Intelligent Services Access Manager FX platform, and supports fixed and tunable SFP optical modules.
“Several vendors also offer the possibility to use fixed wavelength - XG-PON1 or 10G EPON optics," says Vanhastel. "This reduces the initial cost of a TWDM-PON deployment while allowing you to add tunable optics later."
Operators can thus start with a 10 gigabit PON using fixed-wavelength optics and move to TWDM-PON and tunable modules as their capacity needs grow. “You won’t have to swap out legacy XG-PON1 hardware two years from now,” says Vanhastel.
Alcatel-Lucent has been involved in 16 customer TWDM-PON trials overall, half in Asia Pacific and the rest split between North America and EMEA. Besides Vodafone, Alcatel-Lucent has named two other TWDM-PON triallists: Telefonica and Energia, an energy utility in Japan.
You won’t have to swap out legacy XG-PON1 hardware two years from now
Vanhastel says the company has been surprised that operators are also eyeing the technology for residential access. The high capacity and relative expense of tunable optics made the vendor think that early demand would be for business services and mobile backhaul only.
Source: Gazettabyte
There are several reasons for the operator interest in TWDM-PON, says Vanhastel. One is its ample bandwidth - 40 gigabit symmetrical in a four-wavelength implementation - and that wavelengths can be assigned to different aggregation tasks such as backhaul, business and residential. Operators can also pay for wavelengths as needed.
TWDM-PON also allows wavelengths to be shared between operators as part of wholesale agreements. Operators deploying TWDM-PON can lease a wavelength to each other in their respective regions.
Vodafone, for example, is building its own fibre network but is also expanding its overall fixed broadband coverage by developing wholesale agreements across Europe. Vodafone's European broadband network covers 62 million households: 26 million premises covered with its own network and 36 million through wholesale agreements.
First operator TWDM-PON pilot deployments will occur in 2016, says Alcatel-Lucent.
Further reading:
White Paper: TWDM PON is on the horizon: facilitating fast FTTx network monetization, click here
10 Gigabit GPON gets broadband access support
Part 1: XG-PON1 goes commercial
Alcatel-Lucent is making available what it claims is the first broadband access platforms that support XG-PON1, the 10 Gigabit GPON standard. The company has developed an XG-PON1 line card for use in its latest ISAM-FX as well as its existing ISAM-FD access platforms. The ISAM platforms support copper and fibre-based broadband access.
“First [XG-PON1] deployments will likely be in Asia Pacific but we are seeing strong interest from other regions"
Stefaan Vanhastel, Alcatel-Lucent
Why is this significant?
System vendors and operators have been trialling 10 Gigabit GPON technology. Now Alcatel-Lucent has signalled that the technology is ready for commercial deployment. The vendor says operator deployments will start later this year, a claim backed by Infonetics Research. However, the market research firm forecasts 10 Gigabit GPON global deployments will only reach two million ports by 2014.
What has been done?
XG-PON1 is the asymmetrical version of the 10 Gigabit GPON standard delivering 10 Gigabit-per-second (Gbps) data rates downstream (to the user) and 2.5Gbps upstream. This compares to GPON, which delivers 2.5Gbps downstream and 1.25Gbps upstream.
The Alcatel-Lucent XG-PON1 line card has four 10 Gigabit GPON ports, and is available on the existing ISAM-FD products as well as the latest ISAM-FX high-capacity shelves.
There are three ISAM-FX shelves that accommodate four, eight and 16 line cards. The ISAM-FX shelves have a dual-100Gbps backplane capacity, compared to the ISAM-FD which has a 2x10Gbps capacity. The ISAM-FX shelves house up to two controllers, and the role of the backplane is to connect each line card to each controller. The 100Gbps is the capacity linking each line card to each of the two controllers. Since the XG-PON1 line card has four 10Gbps ports, the backplane will clearly support future denser line cards.
The controller acts as a central processing unit taking traffic from the line cards and packaging it for the network uplink. Each controller has a 480Gbps switching matrix, four 10 Gigabit Ethernet uplinks and service intelligence to handle the traffic flows. “You can have two controllers per shelf and then they work in a load sharing mode,” says Stefaan Vanhastel, marketing director wireline access at Alcatel-Lucent. “This gives you a total of eight uplinks and you can add more if needed.”
The PON architecture
The XG-PON1 standard allows operators a straightforward way to upgrade existing GPON networks. “The operator can put the two technologies on the same optical network, with some subscribers on GPON and others on 10 Gig GPON,” says Vanhastel.
Source: Alcatel-Lucent
Moving to XG-PON1 not only provides greater bandwidth but also supports more subscribers on the one fibre. According to Alcatel-Lucent the maximum number of PON end terminals or optical network units (ONUs) that GPON supports is 128, dubbed a split ratio of 1:128. In contrast, 1:128 is the starting split ratio for XG-PON1 while the maximum is 1:512.
Source: Alcatel-Lucent
What next?
Vanhastel admits that existing GPON provides more than enough bandwidth to subscribers. To ensure that a GPON subscriber gets sufficient bandwidth, the average split ratio operators use is 1:18. “With the higher-capacity XG-PON1, the average split ratio could go up significantly,” says Vanhastel.
Alcatel-Lucent says initial deployments of XG-PON1 will start in the second half of this year with more widespread deployments occurring in 2012. “The first deployments will likely be in Asia Pacific but we are seeing strong interest from other regions,” says Vanhastel.
Initial XG-PON1 deployments will likely be for backhauling traffic from fibre-to-the-building (FTTB) deployments. Here one fibre has a split ratio of 1:16 or 1:32 but each FTTB node supports 24 subscribers typically.
Meanwhile, the company announced in October 2010 trials with operators Verizon and Portugal Telecom involving the symmetrical (downstream and upstream) 10 Gigabit GPON variant known as XG-PON2. XG-PON2 has yet to become a standard.