Methods and apparatus for implementing a Home Agent supporting Mobile IP and being capable of allocating one or more networks to a mobile router which registers with the Home Agent comprise receiving a registration request packet from the mobile router, the registration request packet indicating one or more networks being requested by the mobile router from the Home Agent. In one embodiment of the channel scanning method, a receive channel is switched at predetermined intervals, it is checked whether the broadcast contents of the channel being received currently, after the channel switching, will change within the scanning time period, and a time period for receiving the channel is prolonged, if the broadcast contents will change. A collection of particles comprising metalmetalloid oxide have an average particle size from about 15 nm to about 1 micron.