Technical results from TDC vectoring field trial in Folby

Transcription

1 Technical results from TDC vectoring field trial in Folby 14th January

2 Vectoring trial Folby The test site is a part of the village Folby, between Aarhus og Randers 2

3 Vectoring trial general conditions The site is classified as remote exchange. This means that a mix of ADSL2+ and VDSL2 is in use. DPBO is not applied. This makes the site reasonably representative for the crosstalk conditions around small COs and remote exchanges, but not for remote injection points where DPBO is applied and only VDSL2 is deployed In a cable between the remote exchange building and passive distributer HN12 there is a suitable number of VDSL2 customers. 15 additional VDSL2 CPEs (dummy customers) are installed in a shed very close to distributer, in order to increase crosstalk noise (simulating a small apartment block) A few VDSL2 customers did not want to be included in the trial. Luckily, they could all be served on a profile limited to the ADSL2+ frequency band, so alien VDSL2 lines could be avoided There are no unbundled lines or VDSL2 BSA customers in the test area 3

4 Vectoring trial technology The test DSLAM is an ALU ISAM DSLAM with 2 vectoring enabled VDSL2 line cards, type NDLT-F. Dummy customers are connected to one card, the real test customers to the other System level vectoring is applied using a Vectoring processer type NDPS-A, supporting up to 192 ports DSLAM SW version: d The CPEs are Broadcom based modems, Sagem FAST 5310; SW A2pv6F038h The real customers keep their original TDC RGW supporting triple play service, WIFI etc. The vectoring modems are connected between line and RGW (2-box setup) Two alternative CPE units with same chipset type were used for some measurements 4

5 Topologi Sub CO with DSLAM Passive distributer HN 12 Test customers, including dummy customers, are connected to HN12, with the exception of a few real customers connected to drops on main cable to HN12 (400 pairs, binder type) 5

6 General status for trial primo January real customers are connected. 19 of these subscribe to a triple play service with SD and HD TV 15 dummy customers are connected close to passive distributer HN12 (port 1-15) (simulating a small apartment block) 1 dummy customer is connected directly at MDF (0 loop length, used as reference) There is a high fill of active ADSL2+ lines in the cables Test lines are configured with 17a profile with the exception of the longest line where 8b is used. Frequency plan: 998ADE17 6

7 General status for trial primo January 2013 (2) Vectoring is disabled in the ADSL2+ band UPBO ETSI F is used on all lines (standard DK VDSL2 configuration) Loop attenuation vary between 3 and 12 db@150 khz G.INP and SRA is used on all lines All lines are profile capped to max 108 Mb/s in DS. This cab is chosen to avoid limitation of US due to memory limitation in chipsets. A further limitation is the Ethernet 100 Mb/s interface on the CPEs, making it impossible to demonstrate actual rates beyond 100 Mb/s. For some experiments a higher cap was chosen and an alternative CPE unit with 1 Gb interface was used 7

8 Heat map for coupling between pairs Tx Referred FEXT [dbm/hz] LT 1/1/7 Real customers LT 1/1/9 Dummy customers Victim [line no. + (no. board)*100] CROSSTALK MATRIX TRANSMITTER REFERED FEXT Disturber Strong crosstalk present on some lines. Very strong crosstalk between 2 pairs (adjacent pairs in main cable) 8

9 Reach-rate diagram 9

10 Vectoring gain 10

11 Co-existence with ADSL2+ It is clearly seen that bitloading is reduced due to ADSL2+ crosstalk up to bin 512 (2.2 MHz) The drop corespond to 5-6 Mb/s in DS At higher frequencies a smooth roll off is seen Port 22 is connected to a short line 11

12 Other observations and planned measurements The stability of lines is monitored. Some lines show a few errored seconds/15 min. Otherwise the lines are clean (they all fall into TDC stability class Perfect ) In two house installations bridge tabs (10-15 m) were detected and removed by technician. Apart from this, the lines were not touched US vectoring gain will be investigated further. Due to configuration there is at present a cab at 30 Mb/s. Tests with different memory split are planned, and so are test with modified UPBO profile, including no UPBO. The planned tests also included stability tests with G.INP disabled and classical IFEC in use, provoked disorderly leaves, robustness to intermitted RFI ingress etc. The trial will be terminated by the end of February 12

13 Preliminary conclusion The results seen up to now demonstrate that: The expected gain in DS bandwidth is achieved The loss due to not-cancelled ADSL2+ crosstalk noise is as expected The lines serving the real customers are stable and the triple play service is running OK US bandwidth performance need further investigation 13