WIP: Work towards a more real DL TBF receiver implementation
Change-Id: I300312734d99f2b8a406f39e04b4f738940f7579
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@ -113,7 +113,14 @@ module RLCMAC_Types {
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boolean e
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} with {
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variant (e) "FIELDLENGTH(1)"
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encode "RAW"
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};
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external function enc_LlcBlockHdr(in LlcBlockHdr si) return octetstring
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with { extension "prototype(convert) encode(RAW)" };
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external function dec_LlcBlockHdr(in octetstring stream) return LlcBlockHdr
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with { extension "prototype(convert) decode(RAW)" };
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type record LlcBlock {
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/* Header is only present if LI field was present */
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LlcBlockHdr hdr optional,
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@ -18,8 +18,25 @@ import from RLCMAC_CSN1_Types all;
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import from LLC_Types all;
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import from GPRS_Context all;
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/* input parameters into TBF (mostly mode/cs + LLC PDUs */
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private const integer RLC_GPRS_SNS := 128;
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private const integer RLC_GPRS_WS := 64;
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private const integer RLC_EGPRS_MIN_WS := 64;
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private const integer RLC_EGPRS_MAX_WS := 1024;
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private const integer RLC_EGPRS_SNS := 2048;
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private const integer RLC_EGPRS_MAX_BSN_DELTA := 512;
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private const integer RLC_MAX_SNS := RLC_EGPRS_SNS;
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private const integer RLC_MAX_WS := RLC_EGPRS_MAX_WS;
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private const integer RLC_MAX_LEN := 74 /* MCS-9 data unit */
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private const integer sns_half := (RLC_MAX_SNS / 2);
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private const integer mod_sns_half := (RLC_MAX_SNS / 2) - 1;
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/***********************************************************************
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* Uplink TBF handling
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***********************************************************************/
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/* input parameters into TBF (mostly mode/cs + LLC PDUs */
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type record UlTbfPars {
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/* Acknowledged mode (true) or unacknowledged (false) */
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boolean ack_mode,
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@ -46,22 +63,6 @@ private function f_RlcEndpointTx_init(inout RlcEndpointTx ep) {
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ep.v_b := int2bit(0, 128); /* FIXME: EGPRS 2048 bits length */
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}
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type record RlcEndpointRx {
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/* receive state variable V(R) (9.1.5): BSN one higher than highest BSN yet received (mod SNS) */
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integer v_r,
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/* receive window state variable V(Q) (9.1.6): Lowest BSN not yet received (mod SNS) */
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integer v_q,
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/* receive state array V(N) (9.1.7) */
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bitstring v_n
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}
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private function f_RlcEndpointRx_init(inout RlcEndpointRx ep) {
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ep.v_r := 0;
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ep.v_q := 0;
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ep.v_n := int2bit(0, 128); /* FIXME: EGPRS 2048 bits length */
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}
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type record UlTbfState {
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/* "const" input state with TBF Data */
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UlTbfPars tbf,
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@ -360,6 +361,142 @@ function f_ul_tbf_process_acknack(inout UlTbfState us, RlcmacDlCtrlBlock db) {
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}
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}
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/***********************************************************************
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* Downlink TBF handling
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***********************************************************************/
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type record RlcEndpointRx {
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/* receive state variable V(R) (9.1.5): BSN one higher than highest BSN yet received (mod SNS) */
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integer v_r,
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/* receive window state variable V(Q) (9.1.6): Lowest BSN not yet received (mod SNS) */
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integer v_q,
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/* receive state array V(N) (9.1.7) */
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bitstring v_n
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}
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private function f_RlcEndpointRx_init(inout RlcEndpointRx ep) {
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ep.v_r := 0;
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ep.v_q := 0;
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ep.v_n := int2bit(0, 128); /* FIXME: EGPRS 2048 bits length */
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}
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type record DlTbfPars {
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/* Acknowledged mode (true) or unacknowledged (false) */
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boolean ack_mode,
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/* Coding Scheme for transmission, determines block size */
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GprsCodingScheme initial_cs,
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/* Sequence Number Space */
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integer sns,
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/* Window Size */
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integer ws
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}
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type record DlTbfState {
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/* "const" input state with TBF Data */
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DlTbfPars tbf,
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uint8_t num_ts,
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RlcEndpointRx er,
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integer tfi,
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/* list of abstract/decoded RLC PDUs */
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record of RlcmacDlBlock rlc_received
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}
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function f_dl_tbf_mod_sns(DlTbfState ds, integer val) return integer
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{
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return (val mod ds.tbf.sns);
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}
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function f_dl_tbf_is_in_window(integer bsn) return boolean {
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setverdict(fail, "pleaes implement me");
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self.stop;
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}
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function f_dl_tbf_is_received(inout DlTbfState ds, integer bsn) return boolean {
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var integer offset_v_r;
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if (not f_dl_tbf_is_in_window(bsn)) {
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return false;
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}
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/* offset to the end of the received window */
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offset_v_r := f_dl_tbf_mod_sns(ds, ds.er.v_r - 1 - bsn);
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if (not (offset_v_r < ds.tbf.ws)) {
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return false;
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}
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if (ds.er.v_n[bsn mod sns_half] == '1'B) {
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return true;
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}
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return false;
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}
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function f_dl_tbf_mark_received(inout DlTbfState ds, integer bsn) {
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ds.er.v_n[bsn mod sns_half] := '1'B;
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f_dl_tbf_raise_v_r(ds, bsn);
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}
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/* Raise V(Q) if possible */
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function f_dl_tbf_raise_v_q(inout DlTbfState ds, integer bsn) return integer {
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var integer count := 0;
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while (ds.er.v_q != ds.er.v_r) {
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var integer v_q_old := ds.er.v_q;
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if (not f_dl_tbf_is_received(ds, v_q_old)) {
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break;
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}
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ds.er.v_q := f_dl_tbf_mod_sns(ds, ds.er.v_q + 1)
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log("RLCMAC: Taking block ", v_q_old, " out, raising V(Q) to ", ds.er.v_q);
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count := count+1;
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}
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return count;
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}
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function f_dl_tbf_raise_v_r(inout DlTbfState ds, integer bsn) {
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var integer offset_v_r := f_dl_tbf_mod_sns(ds, bsn + 1 - ds.er.v_r);
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if (offset_v_r < (ds.tbf.sns / 2)) {
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for (var integer i := offset_v_r; i > 0; i := i-1) {
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/* mark as missing */
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ds.er.v_n[bsn mod sns_half] := '0'B;
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//raise_v_r_to(1);
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}
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log("RLCMAC: Raising V(R) to ", ds.er.v_r);
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}
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}
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/* process the actual data and update TbfState */
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function f_dl_tbf_process_dl_data(inout DlTbfState ds, RlcmacDlDataBlock db) {
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var integer bsn := db.mac_hdr.hdr_ext.bsn;
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if (db.mac_hdr.hdr_ext.tfi != ds.tfi) {
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setverdict(fail, "Unexpected TFI of DL Data Block ", db);
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self.stop;
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}
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f_dl_tbf_mark_received(ds, bsn);
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if (ds.tbf.ack_mode) {
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/* In RLC acknowledged mode, the receive window is defined by the receive window
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* state variable V(Q) in the following inequality[ V(Q) ≤ BSN < V(Q)+ WS ] modulo
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* SNS */
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if (bsn < ds.er.v_q or bsn > ds.er.v_q + ds.tbf.ws) {
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setverdict(fail, "Unexpected BSN outside of window ", bsn);
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self.stop;
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}
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/* In RLC acknowledged mode, the value of V(Q) shall be updated when the RLC
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* receiver receives the RLC data block whose BSN is equal to V(Q). The value of
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* V(Q) shall then be set to the BSN value of the next RLC data block in the receive
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* window (modulo SNS) that has not yet been received, or it shall be set to V(R) if
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* all RLC data blocks in the receive window have been received */
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f_dl_tbf_mark_received(ds, bsn);
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} else {
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/* In RLC unacknowledged mode, if [V(R) - V(Q)] modulo SNS > WS after updating V(R),
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* then V(Q) is set to [V(R) - WS] modulo SNS. */
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/* FIXME */
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}
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}
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}
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