multislot: Rework of handling control channel / polling

In order to send control blocks to MS and receive control blocks from MS
(polling), it is required to select one timeslot that the MS must be
able to send and receive. The allocation algorithm must take care of
selecting that slot.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/tbf.txt b/src/tbf.txt
index 57254ea3..eab58ba5 100644
--- a/src/tbf.txt
+++ b/src/tbf.txt
@@ -94,11 +94,27 @@ Handling of LLC Frame of downlink TBF and LLC Queue of downlink TBF:
   If a new LLC PDU is attached to LLC Frame during WAIT RELEASE state, the
   state is changed to FLOW (downlink flow is assigned to MS).
 
+
 Handling of LLC Frame on uplink TBF:
 
   Received uplink blocks are appended to LLC Frame of TBF. If the PDU is
   complete, it is forwarded to the upper layer.
 
+
+Control TS:
+  On uplink or downlink assignment, it is required to have one timeslot that
+  can be used to receive and transmit. This timeslot is used at uplink TBF
+  to acknowledge and to assign other TBF. This timeslot is used at downlink
+  TBF to poll acknowledgement and to assign other TBF.
+
+  The first common TS (first_common_ts) is calculated when channels are
+  allocated. After creation of TBF or after assignment to different TS layout,
+  the first common TS is used for control TS.
+
+  The first common TS (and so control TS) must not need to be allocated to
+  MS as uplink TBF. (E.g. in case of non-available USF for this slot)
+
+
 Polling:
   In order to poll uplink control block from MS, a special poll state and
   frame number is stored at TBF. The scheduler reads that value and will not
@@ -109,6 +125,10 @@ Polling:
    - The received frame is bad (BFI).
    - The GSM indicates that the block should have been already received.
 
+  Because polling requires uplink response from MS, the polling must be
+  performed at control TS.
+
+
 Data structures of TBFs and PDCHs:
 
   There is a global structure for BTS.