I have a no-name wireless USB adapter which lsusb identifies as:

Bus 001 Device 003: ID 148f:3070 Ralink Technology, Corp. RT2870/RT3070 Wireless Adapter

Wireless works with the kmod-rt2800usb, -rt2800lib, -rt2x00usb, -rt2x00lib packages installed, this on  trunk r23870.

However, it won't stay up. When I issue 'wifi up', the link comes up:

# iwconfig wlan0
wlan0     IEEE 802.11bgn  ESSID:"my_ssid" 
          Mode:Managed  Frequency:2.452 GHz  Access Point: <edited out> 
          Bit Rate=1 Mb/s   Tx-Power=20 dBm   
          RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=39/70  Signal level=-71 dBm 
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:1   Missed beacon:0

with fairly good signal.  But then after a few minutes it goes down again.

Here's /etc/config/wireless:

config wifi-device  radio0
    option type     mac80211
    option channel  11
    option macaddr    <edited out>
    option hwmode    11ng
    option htmode    HT20
    list ht_capab    GF
    list ht_capab    SHORT-GI-20
    list ht_capab    SHORT-GI-40
    list ht_capab    RX-STBC1

config wifi-iface
    option device   radio0
    option network  wan
    option mode     sta
    option ssid     my_ssid
    option encryption psk2
    option 'key' 'my key'

Any ideas on what is happening here?

It's possible my difficulty is a driver problem.  I have  a Netgear WG111v2 G-adapter that uses the p54 driver.  Replacing the no-name N-adapter with this results after a little reconfiguration with a link that comes up and stays up.

Continuing to work with the Dockstar and trying to get N-wireless connections I bought an Asus Model USB-N13 usb wireless adapter from Amazon.  This has a Ralink 2870 chipset.  When I replaced the Netgear G adapter above with this, I got this complaint in dmesg:

phy0 -> rt2x00lib_request_firmware: Error - Current firmware does not support detected chipset.

After some bumbling around I replaced the file in package kmod-rt2800-usb:

/lib/firmware/rt2870.bin

with firmware extracted from a file on the CDROM that came with the Asus Model USB-N13:

root@dockstar:/lib/firmware# ls -l
-rw-r--r--    1 root     root         29736 Nov  4 11:31 isl3887usb
-rw-r--r--    1 root     root          8192 Nov 10 13:03 rt2870.bin
-rw-r--r--    1 root     root          4096 Nov  4 11:31 rt2870.bin.ipk

Here rt2870.bin.ipk is the original package firmware, and rt2870.bin the ad-hoc installed firmware from the CDROM.

With this in place the USB-N13 works, but erratically.  Oddly enough, the no-name adapter (see above) which also has a Ralink chipset, now seems to work quite well!

wlan0     IEEE 802.11bgn  ESSID:"my ssid" 
          Mode:Managed  Frequency:2.452 GHz  Access Point: <edited out>
          Bit Rate=65 Mb/s   Tx-Power=20 dBm   
          RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=35/70  Signal level=-75 dBm 
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:2  Invalid misc:0   Missed beacon:0