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699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.1.1 Acknowledged Mode (AM)-SAP Primitives and Parameters | Three primitives are defined for the AM-SAP, as shown in Table 4.1. Table 4.1: Primitives at the AM-SAP Primitive Name Direction Parameters BCn_AM_DATA_REQ To BCn Layer Data-PDU, PDCP-Info, CNF, DiscardReq, MUI, BcnID, [Unsegmentable], [SUSP] BCn_AM_DATA_IND From BCn Layer Data-PDU, PDCP-Info, DiscardInfo BCn_AM_DATA_C... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.1.2 Transparent Mode (TM) SAP Primitives and Parameters | Three primitives are defined for the transparent mode TM-SAP, as shown in Table 4.2. Table 4.2: Primitives at the TM-SAP Primitive Name Direction Parameters BCn_TM_DATA_REQ To BCn Layer Data-PDU, DiscardReq, MUI, BcnID, [Unsegmentable] BCn_TM_DATA_IND From BCn Layer Data-PDU, Err_ind BCn_TM_DATA_CNF From BCn Layer MUI ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.1.3 Unacknowledged Mode (UM) SAP Primitives and Parameters | Three primitives are defined for the UM-SAP, as shown in Table 4.3. Table 4.3: Primitives at the UM-SAP Primitive Name Direction Parameters BCn_UM_DATA_REQ To BCn Layer Data-PDU, PDCP-info, DiscardReq, MUI, BcnID, [Unsegmentable] BCn_UM_DATA_IND From BCn Layer Data-PDU, PDCP-info BCn_UM_DATA_CNF From BCn Layer MUI The ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.2 Control Plane Interfaces | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.2.0 General | In the Control Plane, the Bearer Connection Layer interfaces to the Adaptation Layer above. Three SAPs are used in the control plane, namely AM-SAP, CBCn-SAP and COM-SAP. The AM-SAP in the control plane is used for transporting UE specific signalling messages between Adaptation Layer peers. The Adaptation Layer SIG-SAP... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.2.1 CBCn-SAP Primitives and Parameters | The CBCn-SAP is used for the exchange of control messages between the Bearer Connection Layer and the Adaptation Layer. The following primitives are defined for the CBCn-SAP, as shown in Tables 4.4 to 4.6. Table 4.4: Primitives at the CBCn-SAP common to UE and RNC Primitive Name Direction Parameters CBCn_CREATE_REJ To ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.2.2.2 COM-SAP Primitives and Parameters | Two Primitives are defined for the COM-SAP, as shown in Tables 4.8 and 4.9. Table 4.8: Primitives at the UE COM-SAP Primitive Direction Parameters AL_COMDATA_REQ To BCn UE NAS ID and Type, REGM PDU Type, REGM PDU, RetryCount AL_COMDATA_IND To AL REGM PDU Type, REGM PDU Table 4.9: Primitives at the RNC COM-SAP Primitive... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 4.3 Interfaces to the Lower Layer | The Bearer Connection Layer interfaces to the Bearer Control Layer below. Four interface SAPs are defined for this purpose, namely BCt-DATA-SAP for ciphered data, BCt-UCDATA-SAP for un-ciphered data, BCt-COM-SAP for Common Signalling Messages and STATUS-SAP for status information. Their definitions are specified in ETS... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5 Bearer Connection Operations | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.0 General | The following clauses describe the detailed operation of the various entities in the Bearer Connection Layer. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.1 Bearer Connection Manager | The primary function of the Bearer Connection Manager (BCnM) is to respond to AL commands requesting the creation and removal of particular bearer connections and their associated data handlers and SAPs. It is also responsible for the configuration of specific QoS Settings for created data handlers. On receiving a CBCn... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.2 Quality of Service (QoS) Control Function | Each bearer connection has a negotiated Quality of Service (QoS). It is possible that some sources may be unable to schedule to a given QoS. Thus, when sources are exceeding the negotiated QoS, the Bearer Connection Layer will respond by buffering the data, and extend the targeted delivery time (target latency) accordi... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3 Acknowledged Mode Operation | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.0 General | This clause describes the operation of the Acknowledged Mode Data Handler AM_DH, especially the ARQ mechanism and data handling behaviour. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.1 AM_DH Architecture | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.1.0 Overview | The acknowledged mode data handler consists of three major components: a transmit path processing unit, a receive path processing unit and a control unit. Figure 5.1 shows a model of an acknowledged mode data handler. If PDU is first in queue then TdiscardTime(n) = Tnow + max(QueueSize / MeanRate + rtt/2, DiscardLatenc... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.1.1 Transmit Path Processing | At the input of the transmit path unit is the main data storage entity, the TxPDU buffer, where the AM_DH stores all incoming data awaiting transmission. The variable-length PDUs are stored in a FIFO (First In First Out) queue along with information on the whole PDU's target and discard time. Along with the actual data... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.1.2 Receive Path Processing | When a BCnPDU I-frame or sub-segment is received from the Bearer Control Layer, its control information (e.g. poll flag, sequence no.) is first recovered from the header and sent to the AM_DH control. If it is an I-frame, then it is routed to the de-ciphering unit in order to recover the data segment. If it is a sub-se... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.1.3 AM_DH Control Unit | The primary function of the AM_DH Control unit is to provide an interface between the transmit and receive path processing units, in order to handle acknowledged mode control messages (i.e. SREJ and RR). The AM_DH control unit will route any received SREJ and RR poll response messages and implicit acknowledgements embe... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.1.4 Transmit Path Processing in the Suspended State (UESS AM_DH only) | When the BCnM receives the CBCn_SUSPEND_REQ primitive from the AL, it instructs the UESS AM_DH to enter the suspended state and initialize a separate FIFO queue for suspended PDUs ("the suspended PDU queue"). When in the suspended state and an AL PDU is received via the BCn_AM_DATA_REQ primitive, the UESS AM_DH evaluat... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.2 The ARQ Mechanism | An ARQ system fundamentally consists of two independent event driven processes, which communicate asynchronously with each other to exchange data as efficiently as possible whilst avoiding delays and stalls in the data flow. The satellite radio interface ARQ mechanism is based on the standard HDLC (High Level Data Link... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.3 Data Packet Structures | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.3.0 General | The detailed structures of all possible data segments are specified in ETSI TS 102 744-3-3 [9]. The following clauses only summarize the definition of the fields used in the ARQ mechanism. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.3.1 Definition of the I-Frame | An I-frame is used to transmit the actual user data, either new or retransmission. Its header consists of three fields used for the ARQ operations: a Poll Flag (pf), a transmit sequence number (ns) and the expected receive sequence number (nr). The transmit sequence number (ns) is the sequence number of the actual data... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.3.2 Definition of the RR-Frame | A RR-frame is a supervisory frame used to carry either a Poll or Poll Response. It contains a Poll Flag (pf) field and a sequence number field (nseg). When the Poll Flag (pf) is set to 1, the RR-frame is being used as a Poll, and the sequence number field (nseg) shall be set to the sequence number of the latest transmi... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.3.3 Definition of the SREJ-Frame | An SREJ-frame is a supervisory frame used to carry a list of missing segment sequence numbers. It also contains a Poll Flag (pf) field. This shall be set to 1 when the SREJ frame is used as a Poll Response. A SREJ frame shall not be used as a Poll. The list of missing segment sequence numbers is carried in the nr field... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.3.4 Definition of the Sub-Segment Frame | A Sub-Segment Frame is used to carry part of a retransmitted I-frame. Its header contains the sequence number (ns), and segment type (s-type) of the original segment. All sub-segments shall be numbered (ssegn), starting from "0" and can go up to "15". Hence, the mechanism allows the original PDU segment to be split int... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.4 Sending I-Frames | An I-frame is used to send new data or retransmit lost segments. When new data is transmitted, the new segment is given a sequence number (ns = VS), and the next sequence number (VS) is then incremented. If it is a retransmission, then the old sequence number is used, and there is no change in VS. Whenever an I-frame i... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.5 Receiving I-Frames | When an I-frame is received, the value of nr and ns is first checked to ensure that the received I-frame is valid (i.e. VS ≥ nr ≥ VA and (VR - 1 + N/2 - 1) ≥ ns ≥ VR, mod N arithmetic applies (see note)). If the I-frame is invalid, then it shall be discarded. Otherwise, the Poll Flag of the received segment is checked.... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.6 Polling Mechanism | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.6.0 General | The satellite radio interface ARQ mechanism uses a system of Poll / Poll Response to ensure that acknowledgements are sent at regular intervals. Apart from the Poll and Poll Response messages, the system also utilizes an ARQ Timer and internal state variables to operate the Polling mechanism. The following clauses desc... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.6.1 ARQ Timer | The ARQ Timer is used to control the sending of the Poll and the receiving of the Poll response. A Poll can be sent either via the pf field in an I-frame or a Sub-segment frame, or as a RR Poll message. Whenever a Poll is sent, the ARQ Timer is started and the sequence number of the latest transmitted segment is record... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.6.2 Sending a Poll | In order to ensure a Poll / Poll Response pair does not go out-of-sync, the system is restricted to sending one Poll at a time. No more Polls shall be sent until a Poll response is received or the ARQ Timer expires. Any Poll request received in the mean time is delayed. Multiple Poll requests during this time shall be ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.6.3 Response to a Poll | When a Poll is received, the value of ns is checked against VR. If a new missing segment is detected then it is added to the SREJ request list. Any items that still remain in the SREJ waiting list are also transferred to the SREJ request list. Thus, all missing segments are to be re-requested. A Poll Response is then s... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.6.4 Response to a Poll Response | A Poll Response can occur in two forms, from an RR-frame (pf = 0) or from an SREJ-frame (pf = 1). When an RR Poll Response is received, the value of nr is first checked to ensure that it is valid (i.e. VS ≥ nr ≥ VA, mod N arithmetic applies). If it is not valid, then the message shall be discarded. If the RR Poll Respo... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.7 Transmit Behaviour | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.7.0 General | The main decision tree that applies when a Bearer Connection gets an opportunity to send a frame is shown in Figure 5.3. In general, responses to the remote end are given a higher priority than sending activities. The first priority when given an opportunity to send a packet is to notify the remote end of any retransmi... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.7.1 Support for final-seg-retx-allowed (fsr) Mode | If the UE supports the final segment retransmit "fsr" mode then the UE may use this facility if the Bearer Control process signals that the Bearer being used for the transmission supports the this mode of operation. A UE supporting RI-Version 0x83 or later (see ETSI TS 102 744-3-5 [10], clause 6.1.2.2) shall support th... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.8 Receive Behaviour | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.8.0 General | The main decision tree that occurs when an ARQ bearer connection receives a segment from the Bearer Control Layer is shown in Figures 5.4 and 5.5. The receive behaviour depends on whether the BCnPDU contains an I-frame or a sub-segment (see Figure 5.4), or an RR or SREJ supervisory frame (see Figure 5.5). If the receiv... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.8.1 RNC Support for final-seg-retx-allowed ("fsr") Mode | When handling a UE which supports RI-Version 0x83 or later (see ETSI TS 102 744-3-5 [10], clause 6.1.2.2) , the RAN shall consider "fsr" mode active for all AM connections to the UE. When operating in "fsr" mode, the RNC may receive duplicate segments within a single burst transmitted by the UE, for instance if a previ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.9 Tx and Rx Window Size Control | For an Acknowledged mode connection, the transmit window size can be a limiting factor in achieving the maximum throughput. The minimum window size is given by: where ResponseTimeParam is the value used to set the ARQ timer as specified in either the ResponseTime BCn-AVP or ForwardQoSControl BCt-AVP and is used to set ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.10 Acknowledged Mode Timers | The timers used in the acknowledged mode Bearer Connections are summarized in Table 5.1. Table 5.1: Acknowledged Mode Timers Timer Name UE RNC Operation ARQ Timer Yes Yes This timer is used to ensure that the transmitting end of a connection receives up-to-date acknowledgements. The timer is started whenever a Poll is ... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.3.11 Example Retransmission Sequence | This clause gives an example of a possible retransmission sequence. Figure 5.6 illustrates a basic sequence with a single direction data transfer from the Bearer Connection Layer at one end A (BC_A) to the corresponding Bearer Connection Layer at the other end B (BC_B). This retransmission sequence demonstrates the use... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.4 Transparent Mode Operations | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.4.0 General | In transparent mode, data shall be transported across the connection layer without adding any extra PDU overhead. The architecture of the transparent mode data handler (TM_DH) is shown in Figure 5.7. The TM_DH only performs buffering and possibly segmentation operations. On the transmit side, the data PDU received from... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.4.1 Transparent Mode Timers | The timers used in the transparent mode Bearer Connections are summarized in Table 5.2. Table 5.2: Transparent Mode Timer Timer Name UE RNC Operation MaxIdle Timer Yes Yes This timer is used to ensure that un-utilized connection resources are removed. The MaxIdle Timer shall be started at the beginning of the connectio... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.5 Un-Acknowledged Mode Operations | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.5.0 General | In un-acknowledged mode operation, no ARQ is needed, but segmentation, ordered delivery and ciphering are required. This is supported in the Bearer Connection Layer by the Numbered Frame Mode Data Handler (NUM_DH). The architecture of the NUM_DH is shown in Figure 5.8. Figure 5.8: Model of a Numbered Frame Mode Data Ha... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.5.1 Un-Acknowledged Mode Timers | The timers used in the un-acknowledged mode Bearer Connections are summarized in Table 5.3. Table 5.3: Un-Acknowledged Mode Timer Timer Name UE RNC Operation MaxIdle Timer Yes Yes This timer is used to ensure that un-utilized connection resources are removed. The MaxIdle Timer shall be started at the beginning of the c... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.6 Common Signalling Data Handler Operation | The Bearer Connection Layer provides a buffering and status reporting service for the handling of Common Signalling Data. No ciphering is required. The architecture of the Common Signalling Data Handler is shown in Figure 5.9. Figure 5.9: Common Signalling Data Handler Common Signalling PDUs are first buffered at the I... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7 Ciphering Operation | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.0 General | Ciphering is only performed in the Bearer Connection Layer in Acknowledged Mode and Un-Acknowledged Mode operation. For Transparent Mode operation, ciphering is performed in the Bearer Control Layer instead. Ciphering shall be implemented in accordance with ETSI TS 133 102 [2] and ETSI TS 133 105 [3], however, some min... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1 Input Parameters to the Ciphering Algorithm | |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1.0 General | It can be seen from Figure 5.10 that there are five input parameters to the ciphering algorithm, namely CK, COUNT-C, TBCNID, DIRECTION and LENGTH. These are described in detail below. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1.1 CK | The cipher key CK is 128 bits long and shall be applied as specified in [2]. No modification is required for the satellite network. This value is supplied by the AL via the CBCn-SAP using the CBn_SECURITY_REQ message. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1.2 COUNT-C | The ciphering sequence number COUNT-C is 32 bits long and is modified for the satellite network to reflect the counters available in the satellite radio interface protocol stack. In Acknowledged Mode (AM) and Unacknowledged Mode (UM) COUNT-C is composed as follows: • The 10 least significant bits of COUNT-C are equal t... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1.3 TBCNID and BCNID | The translated bearer connection identifier TBCNID is 12 bits long and is available in the BCt-PDU header. This is used to replace the radio bearer identifier BEARER used in the UTRAN ciphering configuration. For UEs that comply with RI-Version 0x83 or later (see ETSI TS 102 744-3-5 [10], clause 6.1.2.2) the transmitte... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1.4 DIRECTION | The direction identifier DIRECTION is 1 bit long. Its value is applied as specified in [2]: DIRECTION = 0 for messages from UE to RNC DIRECTION = 1 for messages from RNC to UE. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.1.5 LENGTH | The length indicator LENGTH is 16 bits long. It specifies the length of the required keystream block in bits and does not affect the actual bits in the keystream block. |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.2 Initialization of Keystream Generator | The initialization of the keystream generator is specified in [4], clause 3.4 for UTRAN. In order to accommodate the input parameters used in the satellite network (as specified in clause 5.7.1), the 64-bit register A shall be set to: COUNT-C || TBCNID || DIRECTION || 0…0 (left justified with the right most 19 bits set... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.3 Maintenance of COUNT-C | This clause specifies the rules that shall be used in order to keep COUNT-C values synchronous at both ends of the connection. In this clause, ns (in lower case letters) refers to the sequence number carried in the received BCn-PDU, while NS (in upper case letters) refers to the value of NS stored as the ten least sign... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.7.4 MBMS Connections | MBMS Connections are shared between multiple receivers, each of which may join at a different time, and the multiple MBMS Connections associated with the same MBMS Service may be initiated at different times. Each MBMS Connection associated with the same MRAB (Multicast Radio Access Bearer) has the same CK value, and t... |
699dc8d2d5b7aed14bd4330dab22869d | 102 744-3-4 | 5.8 Handover Operations | Bearer Connections may need to be handed over to a different Bearer Control Process, e.g. when a UE is transferred from a Regional Beam to a Spot Beam (or vice versa), or when traffic within a beam is being redistributed, or when a UE is crossing spot beam boundaries. In these cases, the LRM will initiate the Handover ... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 1 Scope | The present document defines the Bearer Connection Layer (BCn) peer-to-peer interface of the Family SL satellite radio interface between the Radio Network Controller (RNC) and the User Equipment (UE) used in the satellite network. |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 2 References | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 2.1 Normative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which ar... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. NOTE: While any hyperlinks in... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 3 Abbreviations | For the purposes of the present document, the abbreviations given in ETSI TS 102 744-1-4 [2], clause 3 apply. ETSI ETSI TS 102 744-3-3 V1.1.1 (2015-10) 6 |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4 Bearer Connection Interface | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.1 Radio Interface Layering | As described in ETSI TS 102 744-1-3 [1], the satellite communication protocol is considered as a number of communication layers, as follows: • Adaptation Layer (AL); • Bearer Connection Layer (BCn); • Bearer Control Layer (BCt); • Physical Layer (L1). The satellite radio interface protocol stack is designed to seamless... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.2 Bearer Connection Layer Responsibilities | The function of the satellite radio interface Bearer Connection Layer is to provide a number of different data transport services to upper layers. The Bearer Connection Layer is generic to the radio interface and is responsible for the following: • Queuing; • QoS Policing; • QoS Monitoring; • Segmentation and Re-assemb... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.3 Bearer Connection Layer Overview | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.3.0 General | The Bearer Connection Layer performs peer-peer signalling via Bearer Connection Layer PDUs. The Bearer Connection Layer signalling mechanisms introduce an overhead on the layer above. This overhead is kept to a minimum. |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.3.1 Bearer Connection Layer PDUs | When registration is complete, and whenever a User Plane Connection is established, a Bearer Connection process is established which operates an HDLC-derived mechanism for support of the transfer of information between the RNC and the UE. This mechanism introduces an overhead to each User Plane Protocol Data Unit (PDU)... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.3.2 Bearer Connections | A Bearer Connection is a specific logical connection being handled by the Bearer Connection Layer, and this term is used to refer to the logical connection. Each Bearer Connection has an associated Bearer Connection ID, and has a single Bearer Connection process within the Bearer Connection Layer at both RNC and UE whi... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.3.3 Ciphering | For Bearer Connections operating in Acknowledged Mode (AM) or Unacknowledged Mode (UM), ciphering is also performed in the Bearer Connection Layer. Ciphering may be applied to the data segment of Information PDUs (see Figure 5.2) and Numbered PDUs (see Figure 5.6). A detailed description of how ciphering is performed i... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.4 Conventions used in the present document | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.4.1 Presentation | The following conventions are applied throughout the present document: • In the ASN.1 notation, variable names are always in lower case letters with hyphenation used to improve readability (e.g. ret-bct-pdu-header). Data Types in the ASN.1 always start with an upper case letter and may contain additional upper case let... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.4.3 Boolean Variables | BOOLEAN variables shall be encoded as follows: TRUE ::= 1 FALSE ::= 0 |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 4.4.4 ASN.1 Encoding Rules | The ASN.1 presentation provided in the present document for this interface specification is normative. The encoding rules used for this interface specification are provided in clause 4.3.4 of ETSI TS 102 744-3-1 [3]. |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5 Connection Protocol Data Unit (PDU) structure | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.0 General | The Upper Layer PDUs (such as Adaptation Layer Signalling PDUs, Packet Data Convergence Protocol (PDCP) PDUs, etc.) are segmented into a sequence of Bearer Connection Layer Protocol Data Units (BCnPDUs), if required. The length of each Bearer Connection Layer PDU depends on the physical bearer characteristics and is de... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1 Bearer Connection PDU (BCnPDU) | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.0 General | The Bearer Connection PDU (BCnPDU) is passed to the Bearer Control Sub-Layer across the Bearer Connection Layer to Control Sub-Layer interface. This PDU may contain either raw-data or a formatted-pdu. This choice is implied when setting up the Bearer Connection. A formatted-pdu may contain either an ack-mode-pdu (if op... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.1 RawDataPDU | This payload is used in the BCnPDU to carry user plane data when the Bearer Connection Process is operating in Transparent Mode (TM). Segmentation and reassembly and in-sequence delivery are not supported in this mode and would be the responsibility of the layers above. No overhead is added by the Bearer Connection Lay... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.2 InformationPDU | This format is used to carry numbered data segments when the Bearer Connection process is operating in Acknowledged Mode (AM). The PDU has the following structure, with format as shown in Figure 5.2. InformationPDU ::= SEQUENCE { i-flag BIT STRING (SIZE (1)), -- encode as '0'B pf BOOLEAN, ns SequenceNum, nr SequenceNum... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.3 SupervisoryPDU | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.3.0 General | Supervisory PDUs are used to carry control messages when the Bearer Connection process is operating in Acknowledged mode. Two types of messages, ReadyReceive and SelectiveReject, are defined and are identified by the second two bits in the message header. SupervisoryPDU ::= SEQUENCE{ s-flag BIT STRING (SIZE (2)), -- en... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.3.1 ReadyReceive | The ReadyReceive message is used for the acknowledgement of received data and to indicate the readiness to receive more data. The message has the following structure, with format as shown in Figures 5.3 and 5.4: ReadyReceive ::= SEQUENCE { sc-flag BIT STRING (SIZE (2)), -- encode as'00'B, rr-content CHOICE { rr-ack SEQ... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.3.2 SelectiveReject | The SelectiveReject message is used to request segments to be retransmitted and, if pf is set, the acknowledgement of received data. The message has the following structure, with format as defined in Figure 5.5: SelectiveReject ::= SEQUENCE { sc-flag BIT STRING (SIZE (2)), -- encode as '01'B, pf BOOLEAN, nr SequenceNum... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.4 NumberedPDU | The data type NumberedPDU is used to carry data segments when the Bearer Connection process is operating in Unacknowledged Mode (UM) and in-sequence delivery to the layers above is mandatory. Segmentation and reassembly (subject to a successful transfer of all segments over the radio interface) are also supported. The ... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.1.5 SubSegmentPDU | This format is used to carry subsegments when the Bearer Connection process is operating in Acknowledged Mode (AM). The PDU has the following structure, with format as shown in Figure 5.7. SubSegmentPDU ::= SEQUENCE { sg-flag BIT STRING (SIZE (3)), -- encode as '101'B, reserved BIT STRING (SIZE (1)), ns SequenceNum, nr... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2 Parameters | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2.1 BcnSegType | This parameter type is used to specify the type of the data segment being sent in a message. BcnSegType ::= INTEGER { com (0), bom (1), eom (2), ssm (3) } (0..3) Four different data segment types are possible: bom Beginning of Message, the first segment in a multi-segment message. Com Continuation of Message, an interm... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2.2 BconnData | |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2.2.0 General | This parameter type defines the structure of the data segment and depends on the value of the s-type parameter. The parameter has the following structure, with format as shown in Figures 5.8 to 5.10. BconnData ::= CHOICE { com OCTET STRING, bom SEQUENCE { pdcp-info PdcpInfo, pdu-length PDULength, pdu-data OCTET STRING ... |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2.2.1 PdcpInfo | The PdcpInfo field within the BconnData structure are used to carry information and control flags that are exchanged between peer PDCP processes using a bom or ssm message. PdcpInfo::= BIT STRING (SIZE (5)) |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2.3 SequenceNum | The SequenceNum data type is used to describe ns, nr, or elements in the nrs field. SequenceNum ::= INTEGER (0..1023) |
ddb2a88f8811073a83e6bac030685d32 | 102 744-3-3 | 5.2.4 PDULength | The PDULength field is used to specify the total length of pdu-data carried in a multi-segment message. PDULength ::= INTEGER (0..2047) ETSI ETSI TS 102 744-3-3 V1.1.1 (2015-10) 16 Annex A (normative): ASN.1 This annex collates the data structures in ASN.1 notation from the present document in alphabetical order, in a ... |
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