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...

I've just discovered that newer devices and networks probably don't need my latency hack anymore described in  making your 3G cellular mobile Internet 10x faster for free . According to this overview , the following features introduced for Evolved HSPA (or HSPA+) in 3GPP Release 7 could theoretically fix the issues I've uncovered: Continuous packet connectivity :   With much of the data traffic being in the form of IP data, continuous connectivity is an increasing requirement. To achieve this the HS-DSCH and E0DCH channels have been reconfigured to enable them to be rapidly able to transmit user data. Enhanced CELL_FACH operation:   This enhanced operation is required to assist in maintaining the always-on packet connectivity during periods when there have been little or no activity.

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 ...

I've made a small script for greatly improving response time of 3G cellular data connections while only consuming a minimal amount of transfer quota. It is most noticable when browsing, having interactive ssh sessions and maybe for some remote desktop use cases. The result is basically reducing the 500ms-1500ms initial latency and random ping times to normal rates of below 80ms. Of course this assumes that you have no other problems like reflections, interference, signal strength or congestion. I've experimented with raw UDP, TCP and ICMP packets in different configurations, but sticked with this simple and efficient solution in the end. An even more advanced future implementation could involve STUN and an external server to steadily stream optimally sized and timed UDP packets to the client without ACK requirement. Also, a further enhanced version could closely monitor local transfer conditions and determine if any addition transfer should actually be done. Description fro...