Muxing E1 Over a Single Satellite Link PDF Print E-mail

Muxing over a single satellite

Using the Access Processor platform it is possible to multiplex several terrestrial services across a single satellite link. This is most often multiple E1’s over HSSI or EIA530 Satellite Modems.

The Access Processor is a modular switch, based on an ATM backplane. It’s possible to mux ATM and NON-ATM traffic together into a single ATM cellstream. This makes it ideal for doing “odd” data rates over satellite, that do not fit into the PDH/SDH Hierarchy. For example, its easy to transport 4 x E1 using an E3 PDH Mux. You would use 8.448Mbps and a G.703 Satellite Modem. If you wanted to Mux 2,3,5+ x E1 its pretty difficult unless you use the APSAT.

Terrestrial Interfaces Supported

With our Quad E1 Module its possible for us to Mux up to 32 x E1 per AP8000L Chassis, and we can daisy chain a second Chassis to offer up to 60 x E1.

Using the Metrodata APSAT also gives you the added benefit of being able to transport other services across the satellite link, for example HSSI Data, E1 Voice, 10/100BaseT Data/IP and also ASI based Video.

The interfaces we support on the Terrestrial side are:

  • E1, T1, E2, E3, DS-3, OC-3/STM-1
  • Ethernet 10/100BaseT
  • Serial EIA530
  • ASI Video
  • HSSI (High Speed Serial Interface)

Satellite Modem Interfaces Supported

Metrodata have developed a portfolio of products for interfacing satellite and terrestrial networks. On the APSAT, we have the following interfaces for Satellite

  • G.703 – Fixed Telco rates on the Modem are T1, E1, E2, E3, DS-3
  • HSSI – Up to 90Mbps
  • ASI – Up to 155.52Mbps
  • EIA530 – Up to 20Mbps

ATM Over Satellite  

The APSAT uses ATM to Multiplex and therefore transport the traffic over the satellite link. With E1 transport, this uses ATM AAL.1 Circuit Emulation over a HSSI/ASI or EIA530 interface.

AAL.1 uses a payload of 47 bytes, and adds 1 byte of Sequence Number and 5 bytes of ATM Cell Header.

  • An E1 is 2,048Mbps or 2,048,000bits per second
  • 2,048,000 divided by 8 = 256,000 bytes per second
  • 256,000 divided by 47 = 5,447 ATM Cells per second

In order to get the overhead calculation for using ATM, you need to add on the ATM Cell Header.

  • 5,447 x 53 = 288,681 bytes per second
  • 288,681 x 8 = 2,309,447 bits per second or 2.309Mbps

The APSAT HSSI and EIA530 ATM Interfaces use G.832 framing to give link integrity and performance monitoring, which adds additional overhead. A G.832 frame comprises 4296 bits, of which only 4240 bits are payload.

Therefore to transport an E1 AAL.1 payload (2.309Mbps) using HSSI or EIA530 will require the G.832 framing to be added. (If you use ASI then you do not have this G.832 framing).

  • 2,309,447 x 4,296 divided by 4,240 = 2,339,949 bits per second including G.832 overhead

Then we suggest allowing a 1% overhead margin, to allow for miscalculations:

  • 2,339,949 x 1.01 = 2,363,348 bits per second or 2.363Mbps of satellite capacity is required per E1

This is shown in the following table:

1

x

E1

requires

2,363,348

2.363

Mbps

2

x

E1

requires

4,726,697

4.727

Mbps

3

x

E1

requires

7,090,045

7.090

Mbps

4

x

E1

requires

9,453,394

9.453

Mbps

5

x

E1

requires

11,816,742

11.817

Mbps

6

x

E1

requires

14,180,091

14.180

Mbps

7

x

E1

requires

16,543,439

16.543

Mbps

8

x

E1

requires

18,906,787

18.907

Mbps

9

x

E1

requires

21,270,136

21.270

Mbps

10

x

E1

requires

23,633,484

23.633

Mbps

11

x

E1

requires

25,996,833

25.997

Mbps

12

x

E1

requires

28,360,181

28.360

Mbps

13

x

E1

requires

30,723,530

30.724

Mbps

14

x

E1

requires

33,086,878

33.087

Mbps

15

x

E1

requires

35,450,226

35.450

Mbps

16

x

E1

requires

37,813,575

37.814

Mbps

17

x

E1

requires

40,176,923

40.177

Mbps

18

x

E1

requires

42,540,272

42.540

Mbps

19

x

E1

requires

44,903,620

44.904

Mbps

20

x

E1

requires

47,266,969

47.267

Mbps

21

x

E1

requires

49,630,317

49.630

Mbps

22

x

E1

requires

51,993,665

51.994

Mbps

23

x

E1

requires

54,357,014

54.357

Mbps

24

x

E1

requires

56,720,362

56.720

Mbps

25

x

E1

requires

59,083,711

59.084

Mbps

26

x

E1

requires

61,447,059

61.447

Mbps

27

x

E1

requires

63,810,408

63.810

Mbps

28

x

E1

requires

66,173,756

66.174

Mbps

29

x

E1

requires

68,537,104

68.537

Mbps

30

x

E1

requires

70,900,453

70.900

Mbps

31

x

E1

requires

73,263,801

73.264

Mbps

32

x

E1

requires

75,627,150

75.627

Mbps