Some time ago I started a discussion of 802.11 N problem of Nokia N9 (there is wl1273 802.11abgn wireless in it) at http://talk.maemo.org/showthread.php?t=87276 The issue was that 802.11 N connection speed had been slower than 802.11 G connection speed. Later I executed iw list command on my phone, and the output was:
/home/user # iw list Wiphy phy0 Band 1: Capabilities: 0x30 HT20 Static SM Power Save RX Greenfield RX HT20 SGI No RX STBC Max AMSDU length: 7935 bytes No DSSS/CCK HT40 Maximum RX AMPDU length 8191 bytes (exponent: 0x000) Minimum RX AMPDU time spacing: 8 usec (0x06) HT TX/RX MCS rate indexes supported: 0-7 Frequencies: * 2412 MHz [1] (20.0 dBm) * 2417 MHz [2] (20.0 dBm) * 2422 MHz [3] (20.0 dBm) * 2427 MHz [4] (20.0 dBm) * 2432 MHz [5] (20.0 dBm) * 2437 MHz [6] (20.0 dBm) * 2442 MHz [7] (20.0 dBm) * 2447 MHz [8] (20.0 dBm) * 2452 MHz [9] (20.0 dBm) * 2457 MHz [10] (20.0 dBm) * 2462 MHz [11] (20.0 dBm) * 2467 MHz [12] (20.0 dBm) * 2472 MHz [13] (20.0 dBm) Bitrates (non-HT): * 1.0 Mbps * 2.0 Mbps (short preamble supported) * 5.5 Mbps (short preamble supported) * 11.0 Mbps (short preamble supported) * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps Band 2: Capabilities: 0x30 HT20 Static SM Power Save RX Greenfield RX HT20 SGI No RX STBC Max AMSDU length: 7935 bytes No DSSS/CCK HT40 Maximum RX AMPDU length 8191 bytes (exponent: 0x000) Minimum RX AMPDU time spacing: 8 usec (0x06) HT TX/RX MCS rate indexes supported: 0-7 Frequencies: * 5035 MHz [7] (disabled) * 5040 MHz [8] (disabled) * 5045 MHz [9] (disabled) * 5055 MHz [11] (disabled) * 5060 MHz [12] (disabled) * 5080 MHz [16] (disabled) * 5170 MHz [34] (disabled) * 5180 MHz [36] (disabled) * 5190 MHz [38] (disabled) * 5200 MHz [40] (disabled) * 5210 MHz [42] (disabled) * 5220 MHz [44] (disabled) * 5230 MHz [46] (disabled) * 5240 MHz [48] (disabled) * 5260 MHz [52] (disabled) * 5280 MHz [56] (disabled) * 5300 MHz [60] (disabled) * 5320 MHz [64] (disabled) * 5500 MHz [100] (disabled) * 5520 MHz [104] (disabled) * 5540 MHz [108] (disabled) * 5560 MHz [112] (disabled) * 5580 MHz [116] (disabled) * 5600 MHz [120] (disabled) * 5620 MHz [124] (disabled) * 5640 MHz [128] (disabled) * 5660 MHz [132] (disabled) * 5680 MHz [136] (disabled) * 5700 MHz [140] (disabled) * 5745 MHz [149] (disabled) * 5765 MHz [153] (disabled) * 5785 MHz [157] (disabled) * 5805 MHz [161] (disabled) * 5825 MHz [165] (disabled) Bitrates (non-HT): * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps max # scan SSIDs: 1 Supported interface modes: * IBSS * managed * monitor Supported commands: * new_interface * set_interface * new_key * new_beacon * new_station * set_bss * authenticate * associate * deauthenticate * disassociate * join_ibss * Unknown command (55) * Unknown command (57) * Unknown command (59) * set_wiphy_netns * Unknown command (65) * connect * disconnect
So, I tried to reconfigure my wireless access point and made it use [HT20+][SHORT-GI-20] capabilities with QoS (wmm) enabled. And finally I've managed to get the average file transfer speed =~ 2.75 (seldom 2.85 or even 3.0) megabytes per a second.
So... on the one hand, Wi-Fi N mode in Nokia N9 works, but on the other hand, the benefit in connection speed isn't too encouraging. For example, when I launch my AP with [HT40+][SHORT-GI-40][DSSS_CCK-40][RX-STBC1][MAX-AMSDU-7935] and QoS enabled and try to download a file using a laptop with 300Mbit/s wireless card I get connection speed =~ 10 megabytes per a second (instead of 802.11 G standard 2.6 megabytes per a second) and I see a real benefit of using N mode.
Is iw output correct? What are exact HT capabilities of wl1273 chip? Is it worth recompiling wireless driver for my N9 to get High Throughput or there's no sense because the chip doesn't support HT40?