bkil vs. programming

I've just realized that stock Android 2.1 on the U20i (so called "mimmi") discovers Wifi networks by  passive scanning , and only sends out a few probe requests as an acceleration in case of opening the network list menu after waking up. On the other hand, it seems that both Pulse mini (Huawei U8110 with Android 2.1) and Mango (Xperia mini pro SK17i with Android 4.0.4) use normal active scanning. Common wisdom tells you that passive scanning potentially uses more power. This can happen because the receiver's low noise amplifier and processor can use as much power as the transmit circuit. This is especially plausible because maximum transmit power usually shouldn't exceed 100mW anyway (actually 20dBm EIRP ) which is in the ball park of the wireless chip's total consumption already, let alone the whole chipset or mobile device. Active probing involves sending out a probe request on each channel and listening for a response for a limited short interval. I guess...

Works perfectly with two smarter routers using default settings, but does the well known Android Ice Cream Sandwich dance on a legacy one. It sometimes connects on first attempt, other times after a dozen loops, in the rest of the cases not at all. A loop consists of saved, connecting, authenticating, obtaining IP and scanning. The signal strength goes very low in the authenticating and obtaining IP phases. It spends most of the time displaying obtaining IP address, which takes a few seconds. Lowering the beacon interval does help a bit. Altering channel selection, RTS, TKIP, MAC filtering, preamble type, IAPP, data rate or G-only vs. B/G doesn't make much of a difference. A timing issue related bug in the wireless driver is probable, as loading the router CPU sometimes helps. The router log is filled with the following actions 3 second apart: "syslog: wlan0: WPA2-AES PSK authentication in progress.." Sprinkled with authentication failed and "udhcpd Received a ...