MAC Index
Last updated: July 22, 2008
Overview
The MAC (Medium Access Control) Indices are used by the Forward Channel for multiple functions including MAC channel identification, and preamble identification for both the forward control channel and the forward traffic channel.
A preamble sequence is transmitted with each Forward Traffic Channel or Control Channel physical layer packet. The preamble consists of all `0' symbols. The preamble either identifies the packet as a Control Channel packet (MAC index 2 or 3), or identifies the target access terminal for receiving the Forward Traffic Channel or AT-directed Control Channel packet (The access network uses the MAC index to identify the target access terminal. The MAC Index is assigned by the AN and sent to the AT as part of the procedure for establishing a traffic connection.).
There are 64 MAC Indices (numbered from 0 to 63) available for subtype 0 physical layer, 128 MAC Indices (numbered from 0 to 127) available for subtype 2 physical layer and 512 MAC Indices (up to 383 for MAC channel and up to 255 for traffic preambles) available for subtype 3 physical layer (To set the physical layer subtype, see
Release A Physical Layer Subtype
or
Release B Physical Layer Subtype
). The following table shows how the MAC indices are used. For more description on the forward channels, see
Forward Channel Overview
.
MAC Index
|
Subtype 2 and Subtype 3 Physical Layer
|
Subtype 0 Physical Layer
|
MAC Index
|
MAC Channel
|
Traffic/Control Channel Preamble
|
MAC Channel
|
Traffic/Control Channel Preamble
|
0 - 1
|
Not Used
|
Not Used
|
Not Used
|
Not Used
|
2
|
Not Used
|
76.8 kbps Control Channel
|
Not Used
|
76.8 kbps Control Channel
|
3
|
Not Used
|
38.4 kbps Control Channel
|
Not Used
|
38.4 kbps Control Channel
|
4
|
RA (I channel)
|
Not Used
|
RA (I channel)
|
Not Used
|
5
|
Not Used
|
Broadcast
|
RPC, DRCLock
2
|
F-TCH for Single User packets
|
6 - 63
|
ARQ, DRCLock, RPC
1
|
F-TCH for Single User packets
|
66 - 70
3
|
Not Used
|
F-TCH for Multi-User Packet
|
Not Used
|
Not Used
|
71
4
|
Not Used
|
19.2, 38.4, 76.8 kbps Control Channel
|
72 - 127
|
ARQ, DRCLock, RPC
2
|
F-TCH for Single User packets
|
-
Depending on the allocated MAC index, the subtype 2/subtype 3 physical layer MAC code channels (R-PC, DRC Lock, and ARQ channels) are spread with a 128 bit Walsh code transmitted on either the I or Q channels. When an AT is assigned an even numbered MAC index, the RPC and H-ARQ/L-ARQ channels are time-division multiplexed and transmitted on the I channel while the DRC Lock and P-ARQ channels are time-division multiplexed and transmitted on the Q channel. When an AT is assigned an odd numbered MAC index, the RPC and H-ARQ/L-ARQ channels are time-division multiplexed and transmitted on the Q channel while the DRC Lock and P-ARQ channels are time-division multiplexed and transmitted on the I channel.
-
Depending on the allocated MAC index, the subtype 0 physical layer MAC code channels (R-PC and DRC Lock channels) are spread with a 64 bit Walsh code transmitted on either the I or Q channels. When an AT is assigned an even numbered MAC index, the RPC and DRC Lock channels are time-division multiplexed and transmitted on the I channel. When an AT is assigned an odd numbered MAC index, the RPC and DRC Lock channels are time-division multiplexed and transmitted on the Q channel.
-
The test set does not support multi-user packet transmission.
-
The test set does not support variable rate control channel packet.
|
-
MAC index 0 and 1 are not used.
-
The Control Channel transmissions have a preamble that is covered by a bi-orthogonal cover sequence with MAC index 2 (for the 76.8 kbps data rate) or 3 (for the 38.4 kbps data rate).
-
MAC index 4 is used to transmit the Reverse Activity (RA) Channel symbols.
-
MAC indices 5-63 (for subtype 0) and MAC indices 6-63 and 72 -127 (for subtype 2) are available to be assigned to an access terminal during establishing a traffic connection. The MAC index is then used to cover the RPC, DRC Lock and ARQ (only for subtype 2) Channels associated with the access terminal and identify which access terminal the packet is directed to by covering the preamble of Forward Traffic Channel.
-
For subtype 3, the test set only support MAC indices 0-127.
MAC Index in Active Cell Operating Mode
In Active Cell operating mode, when a connection is established between the access terminal and test set, the test set assigns an MAC index (15, by default) to the access terminal. (Note that MAC Index 5 is always assigned to the AT in the E1966A releases no greater than A.05.11 and E6706A releases no greater than A.02.21. This has to be changed because MAC Index 5 is used for Broadcast in subtype 2/subtype3 physical layer.)
The MAC index parameter is sent in the Traffic Channel Assignment message (see
TAP/ETAP/MCTAP Data Connection Call Flow
).
MAC index can be queried (
CALL:STATus:MS:MACIndex?
) at any time, but a value will only be returned if a session is open (see
Session Open State
). The MAC index that is assigned to the access terminal is displayed on the
Call Setup
screen in the
Access Terminal Information (AN Assigned)
window.
MAC Index in IS-856 Test Operating Mode
In the
IS-856 Test Operating Mode
, the test set does not send any signalling information on the forward link. You must specify an MAC Index value on the test set to match your AT's configuration so that the AT can successfully demodulate the test set's forward link signal. The MAC index you set on the test set is displayed on the Call Setup screen in the
Configuration Information
window.