1. Can multicast be supported by existing subscriber stations?  Or do you need specialized subscriber stations to receive multicast transmissions?

Yes, Multicast is supported in the PMP320 when using Layer 2 convergence mode. Multicast packets that are presented at the AP are broadcast to all SM’s using the multicast channel.  This channel is shared with broadcast traffic and is created by default when running the PMP320 system in layer 2 convergence mode.  The maximum information rate of the multicast channel can be adjusted to determine how much bandwidth is made available to broadcast/multicast traffic.  Operators that want to limit multicast traffic to specific SM’s can tag the multicast traffic with a VLAN.  In this case the SM’s only allow tagged traffic that is part of their VLAN group configuration.  Multicast and broadcast traffic is always sent using the lowest modulation QPSK(1/2) to increase the delivery reliability.

2. Is the multicast feature standards compliant (IEEE 802.16, WiMAX Forum profiles, etc)?

Partially.  The multicast capability in the PMP320 uses the broadcast channel and doesn’t support the WiMAX multicast group / subscription concept.  Instead, the PMP320 uses a single common multicast channel.  This connection ID (CID) is in the range of multicast CID’s defined by the WiMAX forum profile.