Increasing bandwidth using 2 PRISM Cards

Aditya S Chikodi adityasc at
Wed May 14 23:33:53 EDT 2003

Hello everybody,

We are trying to improve the data bandwidth between two PRISM2 based Access
Points by adding an extra PRISM PC Card to each access point. i.e, each AP
having 2 PRISM cards.

We have tried the following setup and are not getting the required results
of the double the throughput. Could anybody point out where we are going
wrong in the following procedure?

a) Setup each card to operate on a different frequency and configure them
with separate ESSID's.

b) Due to the half duplex nature of the radio, configure the AP's such that
one card is dedicated for only TX data and another card for RX data. ie.
Card1-1 and Card2-1 is configured for one pair of transmit and receive. Card
1-2 and Card2-2 is configured for another pair (refer diagram below)

Using this setup, we have been trying to get an increase in data bandwidth
from say theoretically 11Mbps to 22Mbps [or a practical improvement from
5.5Mbps to close to 11Mbps] but to no avail.

The setup is as follows

	Card1-1 - 	ESSID: X, Channel: 3
			Used for only Transmission

	Card1-2 - 	ESSID: Y, Channel: 8
			Used for only reception.

	Card2-1 - 	ESSID: X, Channel: 3
			Used for only reception

	Card2-2 - 	ESSID: Y, Channel: 8
			Used for only transmission

The AP's have WDS links established between the PRISM Cards (Card 1-1 and
Card 2-1, Card 1-2 and Card 2-2).

We have indeed made modifications in the bridging code to take care of this
half duplex based transfer for the corresponding interfaces.

Any pointers in the direction using the above setup or any other suggestion
to improve the data throughput using 2 cards will be highly appreciated.


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