[Ns-developers] Adding Wifi Phy models

[Pavel Boyko]

  Hi!

  Nicola, Mathieu,

On Thursday 26 March 2009 12:51:54 Nicola Baldo wrote:
> The switch latency of Calradio is limited by the channel switch latency
> of the RF chipset (average 150 us, maximum 200 us, according to the
> MAX2820 datasheet). The additional latencies associated with having the
> MAC requesting the channel switch operation are negligible (less than 4
> microseconds). I think that implementing a per-packet channel switch
> strategy with these latencies is feasible, even if of course a faster
> switching would be desirable. Actually, the MAX2820 chipset is several
> years old, so I wonder if faster switching RF chipsets have become
> available in the market in the meanwhile.

  We have measured 200-250 us between two frames transmitted on different 
frequencies using atheros chipset with madwifi driver.

  I've implemented "dirty" channel switch in yans-wifi-{phy/channel}, you can 
take a look on attached diff. Mathieu -- please comment if  you see there any 
mistakes.

  To implement clean channel switch one must also implement MAC level 
SwitchChannelId() to
1. Down interface
2. Wait for all Tx queues to empty
3. Switch PHY channel
4. reset NAV
5. Up interface

  Regards,
  Pavel
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