Cell Relay Archive

[Christian Schuler <schuler@fokus.gmd.de>]

Yi Wang wrote:
> 
> Hi,
> 
> Wireless ATM is one of the major inititives to achieve all ATM
> networking. To deal with errors in wireless environment, researchers
> usually put a specific data link layer under ATM to achieve realibility
> and QoS. There is another approach to deal with error, which
> is done at AAL above ATM layer to combat with errors. Does any friend
> know any progress regarding this "wireless AAL" approach? (As far as
> I know, only NTT's AWA project adopted this method)
> 
> Any information will be appreciated.
> 
> Thanks
> Yi
> Faculty of Computer Science
> University of New Brunswick
Hi,

we are working on wireless ATM projects and have considered the wireless
AAL solution. But there are some serious disadvantages, e.g.

- the AAL protocol is usually end-to-end. If you are using some kind 
  of ARQ, you will have frequent retransmission over the whole network
  even with a short unreliable wireless access link. 

- the error probability increases rapidly with larger packet sizes, be-
  cause a single bit error will cause the loss of a complete PDU

- you will have to modify all applications/adapters based on a specific
  AAL. A wireless AAL would be some kind of mix-up of the layering.

Christian
 
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