TELECOM ACCESS STANDARDS NEWSLETTER NO. 123

August 2000
CONTENTS
1. COMPETITIVE SUPPLY OF ADSL CPE
2. OUTLINE OF THE PROVISIONAL TELEPERMIT PROCESS
3. PROVISIONAL TELEPERMITS
4. INSTALLATION
5. PRODUCT SUPPORT BY SUPPLIERS
6. "JETSTREAM" HELP DESK OFFER

RETURN TO MAIN INDEX


1. COMPETITIVE SUPPLY OF ADSL CPE
 1.1 Introduction
Further to the article on ADSL matters in Newsletters Nos 120 and 121, Telecom is now in a position to offer ADSL CPE suppliers the opportunity to prepare to enter the market for "JetStream" and other ADSL CPE. However, it must be stated from the outset that there may be some risk at this early stage, as explained below.

Radio frequency interference is an issue we are being very cautious about. In view of this, a Telecom-supplied "splitter" (currently regarded as part of the network) and balanced wiring will be mandatory until other options have been fully considered. Another area of concern is the potential for interference between services on the same cable. It is most important that signal levels are kept within the prescribed limits.

Full details of how we intend to go about the Telepermit process in order to ensure a "soft launch" of both Telecom and non-Telecom CPE are covered in Specification PTC 270, the "Draft for Public Comment" of which is now published on our website.

Telecom's "JetStream" service is "full" ADSL to ITU Recommendation G.992.1 and it is recommended that all CPE be designed to the "full" standard. However, there is also a slower speed version of ADSL, the relevant ITU Recommendation for which is G.992.2. Since this service is not being provided by Telecom, all our testing to date has concentrated on the "full" version. Our DSLAM's (the equipment at the local telephone exchange) are understood to support G.992.2 CPE and provision is expected to be made for Telepermitting this class of equipment. This will be done later when testing is completed and specific requirements can be incorporated into our draft PTC Specification.

PTC 270 and this newsletter deliberately refer throughout to "G.992.2", even though this is commonly referred to in the industry as "G.Lite". G.992.2 covers what could be considered the "original" version of G.Lite, which limits the downstream speed to 1.536 Mbit/s and the upstream speed to 512 kbit/s. This was done to reduce operating frequencies within the broadcast band and facilitate "splitterless" operation, which uses separate line filters at each jackpoint (other that used for ADSL). This was done to avoid the need for network operators to install splitters at the customer's site. Over the past year or so, the term "G.Lite" has been expanded beyond the original scope and now applies to "splitterless" services in general. To avoid confusion, the more specific term "G.992.2" is used. The loose term "full" ADSL is used to describe both ITU G.992.1 and T1.413, Issue 2.

The primary aims at this stage are reliable inter-operability and minimal risk of interference with other services. PTC 270 explains our proposed process for granting "Provisional Telepermits" for both classes of CPE.



1.2 Warnings
Some caution by CPE suppliers is needed, as the technology is in its early stages and subject to rapid development. Despite the relevant ITU Recommendation, G.992.1, still being at the pre-publication stage, manufacturers have been working on the current draft and on the apparently more stable US Specification T1.413, which has now been advanced to Issue 2. No doubt there will be further changes, but we understand later editions of the standards are likely to provide backwards compatibility between future DSLAM's and the present generation of modems. Nevertheless, there is no certainty on the issue of future compatibility. This point must be appreciated by all potential suppliers.

Telecom is, understandably, taking a fairly cautious approach with these products until the Standards have "matured" and our PTC specifications have been developed more fully.



1.3 Current position
Telecom is now installing Nokia V.5 DSLAM's, which support CPE to G.992.1, T1.413 Issue 2 (and, provisionally, G.992.2). The V.5 DSLAM cards are coming into service as part of the replacement programme for the earlier V3 version, which supported M10 modems. The later M11 and other modems, which are compatible with the V5 DSLAM, will be made available to those new customers taking "JetStream" service with a Telecom-supplied modem.

The replacement programme will take time to complete and it is not expected that there will be sufficient quantities of DSLAM's available to meet all demand until at least the end of September. In the meantime, CPE suppliers will be able to try out their own products and prepare for a full market launch in October - assuming all goes well.

Telecom has already undertaken testing of several other ADSL CPE products and will be putting samples into service. These have been granted "provisional Telepemits" under the conditions described in PTC 270. The performance of these products will be monitored carefully over the next few weeks.



1.4 Interference with other services
"JetStream" operates over a standard copper customer line at frequencies in the range 25.8 KHz - 1.1 MHz. Relative to operation at voiceband frequencies, both the loss on copper cable and the crosstalk coupling between pairs increase markedly with increase in frequency. A compromise has to be made between increasing the signal level to compensate for the increased loss versus having so much signal that there is interference with other services on the same cable. "Power Spectral Density" (PSD) - the amount of power in a specified bandwidth across the operating range, is a key parameter in determining the overall impact of interference for each particular modulation scheme.

The ITU Recommendations cover PSD requirements in line with "international" practices and all ADSL CPE and our DSLAM's must meet these requirements.



1.5 Radio interference potential
The frequencies sent "downstream" by the Telecom DSLAM for "full" ADSL overlap the broadcast radio band and have the potential to cause radio interference unless the signals are sufficiently suppressed. There is still a predominance of 3-wiring in New Zealand homes, despite efforts over the past 4 years to up-grade premises to 2-wiring. The presence of inherently imbalanced 3-wiring, plus earlier installations with old low quality cabling, mean that splitters have to be installed to ensure that RFI levels will not be unacceptable. The splitter is currently part of the network service and will be installed, along with the data jackpoint, by Telecom staff - at least during the early stages. Telecom is also looking into various types of line filter in an effort to simplify wiring issues, but the use of a splitter has so far proved the most reliable approach.

Should a customer later choose to purchase G.992.2 CPE, there is every likelihood that the customer will up-grade to full ADSL when a wider range of information content is introduced, such as "streaming video". Even though G.992.2 is regarded as a "splitterless" service in many overseas countries, our 3-wiring and possible CPE up-grades to "full" ADSL mean that it is safest to install splitters pending more information on the use of line filters and locating suitable types for local use.



2. OUTLINE OF THE PROVISIONAL TELEPERMIT PROCESS
 2.1 Preliminary tests
Enquiries to date have covered a large number of products and revealed a lot of potential support from manufacturers wishing to enter this market. This suggested that CPE suppliers' own resources could be used to make initial compatibility tests of their products and sort out the best types to market, before formal testing of the selected types is undertaken by Telecom. This will avoid overloading our testing facilities and causing unnecessary delays.

The recommended first stage is thus a "supplier assessment', whereby a supplier with access to the "JetStream" service with an M11 modem as a "reference" may request permission to connect their own CPE for initial testing purposes. We will require the supplier's assurance that the product is covered by a safety test report to AS/NZS 3260, IEC 60950, or their direct equivalent, and an EMC test report to AS/NZS 3548 (CISPR 22), or their direct equivalent.

Suppliers wishing to carry out such testing are to apply in writing to Access Standards, using the "Application for ADSL Trial" form on our website, to show the product brand and type and the chosen test location. Note that where a Nokia M10 modem is installed, the DSLAM used will not be suitable for trial purposes.

For suppliers, it will be essentially a case of "try it and see how it goes". Those suppliers with appropriate technical expertise can then carry out any necessary software changes and determine whether their products can access the internet via the Telecom "JetStream" service. Such tests are purely "functional" and do not cover all Telepermit requirements. The invitation to supply "evaluation" samples to Telecom (Newsletter No. 121) is now withdrawn.

If access to "JetStream" is not available at the time required, it will be a matter of applying to have laboratory testing carried out as the first stage. This work could be delayed or complicated if the product has not been pre-tested to ensure adequate functionality.



2.2 Formal testing
Preferably with some assurance that a product works to their satisfaction in the "one-off" trial situation, the supplier may apply to Telecom for formal laboratory testing to PTC 270. It must be stressed that while these tests will be used for granting a "provisional Telepermit", they will not be comprehensive enough to totally avoid risk of CPE mis-operation in all applications. Also, Telecom is not able to provide a consultancy service to suppliers whose products fail the tests.

Telecom will be moving to accredit independent testing facilities in due course but, initially, provisional agreement to connect ADSL CPE will be based on testing by Telecom Network Delivery Group's Engineering Support Laboratory in Wellington. This laboratory will assist in developing formalised test procedures for later use by other test laboratories, but initial work will be based mainly on the above PSD measurements and functional testing (basic internet operation) against the Nokia V.5 DSLAM.

Where specialised applications are to be supported by a product, it will be the supplier's responsibility to ensure that the product performs as claimed. Such testing is not done by Telecom.



2.3 Overseas independent inter-operability testing
Where a product has already been subjected to independent testing, suppliers are invited to submit the results. However, such results are not directly relevant to the grant of a provisional Telepermit.



3. PROVISIONAL TELEPERMITS
 3.1 Applications
On receipt of a compliant Telecom test report, the supplier can apply to Access Standards for a "provisional" Telepermit in accordance with PTC 270. Note that it is also necessary to submit a Declaration of Conformity with Class B of AS/NZS 3548: 1995 to the Ministry of Economic Development. This is not a direct Telecom issue, but is required by law and should not be overlooked.



3.2 Provisional Telepermits
A "provisional Telepermit" is very similar in concept to the Limited Permit trial arrangements applied to PABX and other complex equipment for which full testing would be expensive or impracticable. The "provisional Telepermit" will cover the installation of up to 100 units of the product concerned. Because product will be much more widespread, even with only a hundred or so units of each type, there will be one major change from the usual Limited Permit trial. In this case, Telepermit labels will be issued and affixed to the products concerned.

These "provisional Telepermits" will be issued in the PTC 272-series for G.992.1 "full" ADSL CPE and, later, in the PTC 273-series for G.992.2 ADSL CPE. This will ensure that all products supplied to customers under the present limited testing process, will be easily identifiable in the event of any future compatibility problems. If future PTC requirements prove to be significantly changed, different PTC-series will be used for CPE to the later version specification.

The grant of a "provisional Telepermit" is conditional upon the supplier fully supporting the product for end users. Customers are to be advised that all difficulties are to be dealt with initially by the supplier, and that only when customer/supplier investigation clearly indicates a network fault, should this be reported to Telecom. These first installations are to be monitored closely by the supplier's support staff, further installations being deferred if problems arise.

The total number and rate of new installations is hard to predict in a highly competitive open market and Telecom's supply of DSLAM's could well be exceeded, even from October onwards, when supplies of DSLAM's are expected to be more plentiful. There are likely to be network equipment changes and, of course, continuing software changes in the various types of CPE. CPE suppliers will thus need to monitor the situation carefully and take responsibility for ensuring ongoing inter-operability.

Telecom is putting processes in place to expedite customer provisioning and commissioning and these are expected to be in place by October. In the meantime, the process is largely manual and customers will be asked to quote the Telepermit number of their CPE when applying for "JetStream" service. This will assist our staff in identifying products and make it clear that a Telecom-supplied M11 modem is not required.

The above reasons more than justify a "soft start" at this early stage. When installations are proceeding with no serious difficulties, the supplier is to advise Access Standards of the number installed and seek to have the initial limit increased. We will check with our JetStream Help Desk to confirm that there are no significant numbers of complaints about the product concerned.



3.3 "Full" Telepermits
Once ADSL has "settled down" and everyone has gained more experience with this service, our aim is to define and confirm any additional interface requirements. We expect to publish these as the "Draft for Public Comment" of either a new PTC specification or a revision of PTC 270. The future specification is expected to cover more comprehensive test requirements for inter-operability with the Telecom DSLAM.

Provisional Telepermits are expected to be phased out soon after the proposed specification has been published. Reasonable notice of this requirement will be given. The product concerned will then be required to meet any new or changed mandatory requirements in full in order to be granted a "full" Telepermit. Earlier products which cannot meet these later requirements may have to be withdrawn from sale, especially if they are giving rise to customer complaints due to non-compatibility with the network.



4. INSTALLATION

When the customer applies for "JetStream" service, Telecom will install the splitter for "JetStream" in the External Test Point (ETP) or at some location close to the entry point. Other installation options are under active consideration.

Where necessary, Telecom staff will also install a 2-pair cable (conforming with PTC 222) run directly from the splitter to the jackpoint at which the customer's PC and modem will be connected. No other jackpoints or CPE in the premises are connected on the pair used for ADSL. The ADSL cable pair must be kept balanced to earth to minimise the risk of radio frequency radiation and potential interference to any domestic broadcast radio receivers in the vicinity.

"3-wiring" is unacceptable for ADSL services. Such wiring is inherently unbalanced to earth and would act as a radio antenna at the operating frequencies used.



5. PRODUCT SUPPORT BY SUPPLIERS

Suppliers are required to provide full support for their products but, initially at least, there will be a need for co-operation between Telecom and other CPE suppliers to define and overcome any service problems. It is strongly recommended that each CPE supplier operates a "free" customer help line (not a "0900" chargeable number), which will provide some level of focus on all problems affecting that supplier's products. For its part, Telecom runs a "JetStream Help Desk", which will be able to liaise with each individual supplier's help desk, check progress via fault reports, and advise our Development group of any common problem issues.

Should Telecom investigations reveal that third party CPE is responsible for frequent service problems, then the provisional Telepermit will be suspended, pending agreed resolution and correction of the cause. Depending on the circumstances, CPE of the same type already sold and in service may also be required to have remedial action taken as a protective measure.

Supplier support is essential because of the wide range of computers in service and the even wider range of software installed in them. Telecom has found that a lot of effort may be expended in sorting out problems in the customer's equipment.

To avoid site visits wherever possible, it is recommended that modems be pre-installed in or with the customer's computer by the supplier, especially where correct operation can be confirmed on a "JetStream" line at the supplier's premises. Whether the product is an internal PC card or an external device, it will be advisable to set up the software and confirm its correct operation at a central point where the service is known to be available with an acceptable speed of operation. This is especially desirable during the "provisional stage" when there are probably software and setting-up improvements still to be made.



6. "JETSTREAM" HELP DESK OFFER

Staff at Telecom's "Jetstream Help Desk" are keen to co-operate with CPE suppliers to make sure the service is successful. PTC 270 outlines an offer to any suppliers who are interested in co-operating on this issue.

In brief, suppliers are invited to loan a sample of their Telepermitted product, along with software, manuals, etc, to the "Jetstream Help Desk" to Mark Barlow, ADSL Technical Advisor. Mark's contact details are; telephone (09) 488 9628, fax (09) 489 1648. His email address is mark.barlow@telecom.co.nz.

During the "provisional" Telepermit period at least, Mark's team are hoping to loan a wide range of samples for a month or so, in order to gain familiarity with them and be able to "walk" a customer through the set-up process to clearly determine whether a problem is "network" or "CPE" related.

This proposal does not impact on the requirement for each supplier to fully support their own products and provide a suitable help desk, but it should help build co-operation between The Telecom and supplier help desks and aid all concerned in locating and fixing common problems. This information can then be used to develop Telecom's customer care processes and diagnostics.




DOUG BURRUS
Manager
Access Standards