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Products - TDM over IP - E1 T1 over wireless
 

E1 T1 over wireless

Patapsco have a great deal of expertise in delivering E1 and T1 TDM circuits over wireless and WiMAX networks.

The standard PacketBand-TDM-D versions provide an excellent service across wireless networks, better than any other we have seen. Furthermore, they also support the wireless stable clock mode (as described in the box opposite) which can provide a better recovered clock in certain cases.

The TDM-E variants support Asymmetrical Clocking (see opposite) which may provide further enhancement to clock recovery and stability whilst also reducing jitter across the link.

Patapsco have worked with, and used, many wireless vendors’ equipment. Redline of Canada tested available TDM over Ethernet solutions and found the PacketBand to the best performing, best supported and the best overall value. Working together the two companies have developed a specific range of single-port and 4-port PacketBand units to compliment the Redline range (AN80i, AN100U, AN30 and others)  for Redline Partners and customers.
Product datasheet PacketBand-RL1
Product datasheet PacketBand-RL-4
  Press Release
AN80i Pseudowire Guidlines
(requires Registration)
  AN80I and PacketBand (requires Registration)
 
  Single-port TDM over Ethernet/Wireless
  4-port TDMover Ethernet/Wireless
  8-port TDMover Ethernet/Wireless
  V35/X21 over Ethernet/Wireless
  32 Port Chassis
   
Should you need any assistance, please contact Patapsco.
   
   
   
Wireless and WiMax
 
Wireless and WiMax networks have some unique characteristics which can present a challenge to any TDM over Ethernet solution, even one as good as the PacketBand.

To meet this challenge Patapsco have developed two specific clock-recovery processes for wireless systems running G.703 interfaces:

  • Asymmetrical Clocking:
    This facility allows the IP packet size to be defined in single byte increments rather than the normal 32 byte increments.  In addition the Tx and Rx packet size can be configured to different values

  • Recovery Algorithm:
    A specific variant of the intelligent algorithms has been developed that provides a very stable clock but which is not specifically targeted at the G.823 Synchronous mask.
The Asymmetrical method overcomes a TDM over wireless phenomenon known as “beating”. Beating can occur when the TDM over Ethernet packets are launched at the same frequency as the core radio transport frequency.  Many radio systems use an 8Khz transport frequency, in this case the normal TDM over IP 32byte increment packet size also sits on the 8Khz frequency. 

It is possible that the interference of the two transmission systems will cause the beating effect, the symptom of which will be large and frequent changes in PDV (jitter).  The additional PDV induced by the beating effect means that very accurate clock recover can be very challenging, even to a PacketBand Configuring the G.703 TDM over Ethernet transport so that it is no longer based on multiples of 32 bytes helps avoid the frequency conflict and therefore the beating effect. Running different sized packets in both directions has also improved performance on some systems. There is no disadvantage in running the above configurations.

The wireless specific recovery algorithm is designed to provide a very stable clock is a variant of our standard advanced algorithms.  However, in this mode the output clock is changed less frequently in response to in-coming data. This means any changes are averaged over a longer period.  This feature provides a very stable clock which moves little and like all PacketBands is, over a period of time, locked absolutely to the source clock.

FAQs

For more information and to discuss your application please contact Patapsco.

  
 
 
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