GPRS/EDGE Basics / knowledge sharing


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This Presentation Gives Basics of GPRS and EDGE Network. With Brief Introduction to Advanced Ideas are shared in these slides.

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  • Mobility Management = Attach & Detach, RAU, Authentication & Ciphering, Paging, P-TMSI
    Session Management = PDP context activation, deactivation and modification
  • Gc interface not supported by Nokia
  • - Gn is open
    - Gb and Gi are open
    - Gc not supported by Nokia
  • 22,5° offset to avoid origo crossing!
    Peak to average ratio 3,2 dB
    Min to max ratio 16 dB.
  • Why avoid zero-Xing? Zero-Xing will lead to any possible interpretation of phase state from the decoder on the receiver side, so avoiding zero-Xing it’s a way to reduce the risk of misinterpretation of the right bit combination.
    Any combination from star to solid dot is possible as well as from solid dot to star. All of this combinations avoid the zero-Xing.
  • Back-off needed due to linearity requirements.
  • This slide is a recall of GPRS coding scheme structure for comparing GPRS and EGPRS coding schemes on the next slides.
  • Emphasize Code Rate and Header Code Rate…
    Code rate:
    Radio block data part before coding /Radio block data part after puncturing,
    e.g. for MCS-7: 468/612=0,76
    Header code rate:
    Header part before coding/Header part after coding & puncturing,
    e.g. for MCS-9: 45/124=0,36
    for MCS-4: 36/68=0,53
    Note: header part here does not comprise USF & SB
  • Header and payload is separated in EGPRS. (Those are not separated in GPRS!)
    General idea of how a piece of payload information is handled when transmitted
    "Additional info" consits of
    Info whether this is the last block or not
    Block check sequence (first step of coding procedure)
    Tail bits (needed in coding)
    Header part consits of
    Resource usage
    To whom this block
    How should be acknowledged
    Is power reducted
    Which coding & punturing is used for data
    Header type
    How many radio blocks are still to come
    Three different up- and downlink header types for EGPRS (MCS-7, 8, 9, MCS-5, 6, MCS-1, 2, 3, 4)
    The purpose of the definition of the GPRS MS Classes is to enable the different needs of the various market segments to be satisfied by a number of MS types with distinct capabilities.
    CLASS A:
    Supports simultaneous attach, simultaneous activation, simultaneous monitor, simultaneous invocation and simultaneous traffic.
    CLASS B:
    Simultaneous traffic shall is not supported. The mobile user can make and/or receive calls on either of the two services sequentially but not simultaneously. The selection of the appropriate service is performed automatically, i.e. an active GPRS virtual connection is put on hold, if the user accepts an incoming circuit switched call or establishes an outgoing circuit switched call.
    Supports only non-simultaneous attach. Alternate use only. If both services (GPRS and Circuit Switched) are supported then a Class C MS can make and/or receive calls only from the manually or default selected service, i.e., either GPRS or Circuit Switched service. The status of the service which has not been selected is detached i.e., not reachable.
  • EDGE will provide the solution for operators wanting to offer personal multimedia services early and who need to increase the data capacity in their GSM network.
    EDGE will not replace existing investments or services but will upgrade them to a highly competitive level through gradual investment.
    EDGE rollout can satisfy increased data demand and produce increased revenues by first launching an EDGE service in urban and office environments for business users and then providing wider area coverage as private usage takes off.
    EDGE offers data services comparable to 3rd generation prior to UMTS deployment. EDGE is especially valuable for operators that do not deploy UMTS.
  • The Dynamic Abis pool must be created on the PCU where the NSEI (used for the BTS) is defined. The Dynamic Abis pool must also be created on the same ETPCM where the TRX signaling is located.
    Note that GPRS territory downgrade is performed during EDAP creation.
    To enable EGPRS in a cell the dynamic Abis pool has to be created first and then create a TRX which uses the pool
    When the TRX using the dynamic Abis pool is created, GPRS must be disabled in the cell
    GPRS must be enabled in the cell (parameter GENA set to Y) and EGPRS enabled in the BTS (parameter EGENA set to Y) in order to enable EGPRS traffic in the BTS
    If GENA is set to N then EGPRS traffic is also disabled
  • EDAP in BSC must be inside the TSL boundaries defined in the BTS side:
    This requirement has to be taken into account also when modifying EDAP size or changing the first and/or the last timeslot. The timeslot indexes in the BSC and BTS also have to match, regardless of how the timeslots are routed through the transmission network. In other words, when modifying EDAP the size of EDAP in the BTS has to be the same as the size of EDAP in the BSC.
  • No Priority on CCCH
    S9 Shared
    S10 Dedicated PBCCH (PCCCH)
  • Ask trainees about expected durationof READY and STANDBY Timers (I.e. 44 seconds and 1-2 hours)…
    STANDBY timer should be 2x > Periodic RA Update Time.
    In IDLE mode no GPRS Mobility Management
    In STANDBY mode Routing Area Update are performed
    In READY mode a Cell Update is performed when the MS changes the cell
  • QoS is like type of APNs (Access Point Names) available to the user.
  • TFI - temporary flow identity,
    PACCH - Packet Associated Control Channel used for Acknowledgements.
  • 7 UL because of 3 bits for USF (8 - 1 reserved = 7)
  • Not like a mux but a "tolken / round robin" scheme
  • GPRS/EDGE Basics / knowledge sharing

    2. 2. (E)GPRS OBJECTIVES “2G Data EXPLAIN” Main topics • Basic GSM/GPRS/EDGE data network functionality Concepts • (E)GPRS = GPRS & EDGE • EGPRS = EDGE
    3. 3. (E)GPRS - Content Functionality • NE & interfaces • Protocol stack • TBF, Session Management, Mobility Management Base Station Subsystem ( BSS ) • Modulation (Air interface), • EDAP and PCU (Resource allocation) • Gb
    4. 4. SW and HW Releases This material describes the Nokia (E)GPRS System with the following SW and HW releases: • BSS SW: • BSS10.5, 11.0 and 11.5 and S12.0 • BSC variants with PCU1: • BSCi, BSC2, BSC2i, BSC3i • BTS versions: • Talk, PrimeSite, MetroSite, UltraSite • SGSN • SG5.0
    5. 5. CONTENT :- 1 Introduction • Network Architecture and Interfaces • Mobile Classes • Network Protocols • Multiframe and Header Structure • Air Interface Mapping – Physical and Logical Channel Procedures • State and Mobility Management • GPRS Attach/Detach • Routing Area • Session Management (PDP context) • Temporary Block Flow •RLC/MAC Header •TBF Establishment
    6. 6. GSM & (E)GPRS Network Architecture Um PSTN Network BSC BTS PC U HLR/AuC EIR MSC Gb EDAP Border Gateway (BG) Serving GPRS Support Node (SGSN) SS7 Network Corporate 1 Billing System Router PAP U GPRS backbone network (IP based) Server Charging Gateway (CG) Local Area Network Data network (Internet) Corporate 2 Server Lawful Interception Gateway (LIG) Inter-PLMN network GPRS INFRASTRUCTU RE Gateway GPRS Support Node (GGSN) Router Data network (Internet)
    7. 7. (E)GPRS Network Elements and Primary Functions • • GGSN • Session Management • GTP tunnelling to other GSNs • Secure interfaces to external networks • Charging & statistics • IP address management Domain Name Server • Translates IP host names to IP addresses (DNS Resolution) • Makes IP network configuration easier • In GPRS backbone SGSN uses DNS to get GGSN and SGSN IP addresses (APN Resolution) • Two DNS servers in the backbone to provide redundancy Charging Legal Interception Gateway • Enables authorities to Gateway intercept subscriber data • CDR and signaling consolidation • Chasing criminal activity • Forwarding CDR • Operator personnel has Enables GPRS information to very limited access to LI billing center roaming functionality Standard Nokia IP • LI is required when router family launching the GPRS service SGSN • Mobility Management • Session Management • MS Authentication • Ciphering • Interaction with VLR/HLR • Charging and Border Gateway • statistics Interconnects • GTP tunnelling to different GPRS operators' other GSNs backbones
    8. 8. GSM and (E)GPRS Interfaces SMS-GMSC SMS-IWMSC E SM-SC C Gd HLR MSC/VLR D Gs A Gb TE MT R BSS Um Gn Gc Gr Gi GGSN SGSN Gn EIR Gp Gf SGSN GGSN Other PLMN Signaling Interface Signaling and Data Transfer Interface PDN TE
    9. 9. (E)GPRS Interfaces TE R MT Um BSS E MSC/VLR A D HLR SMS-GMSC SMS-IWMSC C SM-SC Optional Gb Gs Gr Gc Gd SGSN Gn SGSN Gp GGSN Gf EIR LAN SW / IP BB Gn Gn DNS Ga Gn GGSN Gn CG Other PLMN Signaling Interface Signaling and Data Transfer Interface LIG Gi PDN TE
    10. 10. GMSK & 8-PSK - Phase State Vectors Envelope (amplitude) Time GMSK (0,0,0) Envelope (amplitude) (0,1,0) (0,1,1) 8PSK (0,0,1) (1,1,1) (1,0,1) (1,1,0) (1,0,0) 22,5° offset to avoid zero crossing Time
    11. 11. 8-PSK Modulation Phase states transitions to avoid zero-crossing (d(3k),d(3k+1),d(3k+2))= (0,0,0) 3π/8 (0,1,0) (0,1,1) (0,0,1) (1,1,1) (1,1,0) (1,0,0) Gross rate/time slot selected as the new modulation added in EGPRS • 3 bits per symbol • 22.5° offset to avoid origin crossing (called 3Π/8-8-PSK) • Symbol rate and burst length identical to those of GMSK • Non-constant envelope ⇒ high (1,0,1) Modulation Symbol rate Bits/burst • 8-PSK (Phase Shift Keying) has been EDGE 8-PSK, 3bit/sym 270.833 ksps 348 bits 2*3*58 69.6 kbps requirements for linearity of the power amplifier • Because of amplifier non-linearities, a 24 dB power decrease back-off (BO) is typically needed, Nokia guaranteed a BO of 2 DB for BTS GSM + EDGE GMSK, 1 bit/sym 270.833 ksps 114 bits 2*57 22.8 kbps
    12. 12. GMSK and 8PSK Bursts dB +4 +1 -1 -6 (**) Phase state vector diagram •Amplitude is not fixed •Origin is not crossed •Overshooting - 30 (***) (147 bits) (*) 10 µs 8 µs 10 µs 7056/13 (542.8) µs 10 µs 8 µs t 10 µs GMSK Burst dB +4 +2,4 0 -2 -6 (***) -20 (147 symbols) -30 (**) s 7056/13 (542,8)µ (*) 10 8 10 2 2 22 10 8PSK Burst 8 10 s) t (µ
    13. 13. 8-PSK Modulation – Back-off Value • Since the amplitude is changing in 8-PSK the transmitter non-linearities can be seen in the transmitted signal • These non-linearities will cause e.g. errors in reception and bandwidth spreading. • In practice it is not possible to transmit 8-PSK signal with the same power as in GMSK due to the signal must remain in the linear part of the power amplifier • The back-off value is taken into account in link budget separately for UL / DL and bands: 900/850, 1800/1900) • Too high MCA (8PSK) can lead to unsuccessful TBF establishment, if the MS is on cell border with low signal level (so the back-off is taken into account) and / or low C/I Pout Compression point Back Off= 4 dB Peak to Average of Pin ≅ 3,2 dB
    14. 14. Burst Structure • Burst structure is similar with current GMSK burst, but term 'bit' is replaced by 'symbol' • Training sequence has lower envelope variations • Seamless switchover between timeslots • In case of max output power only, back-off applied to 8-PSK TSL0 BCCH GMSK TSL1 TCH GMSK TSL2 TCH GMSK TSL3 TCH GMSK TSL4 TCH GMSK TSL5 PDTCH 8-PSK/ GMSK TSL6 PDTCH 8-PSK/ GMSK TSL7 PD CH T 8-PSK/ GMSK P(dB) t(us)
    15. 15. EDGE Signal 1 2 3 4 1. Spectrum of Unfiltered 3pi/8 8psk modulation. 2. Filtered to fit GSM bandwidth. 3. Constellation after filtering: error vectors introduced. 4. Constellation after receiver Edge (equalised) filtering
    16. 16. GPRS Coding Schemes • GPRS provides four coding schemes: CS-1, CS-2 and with PCU2 CS-3, CS-4 • PCU1 and 16 kbit/s Abis links support CS-1 and CS-2, the Dynamic Abis makes it possible to use CS-3 and CS-4 • Each TBF can use either a fixed coding scheme (CS-1 or CS-2), or Link Adaptation (LA) based on BLER • Retransmitted RLC data blocks must be sent with the same coding as was used initially
    17. 17. GPRS Coding Schemes Nokia GPRS CS3 PCU2 CS4 • • 181 9.05 268 13.4 312 15.6 428 21.4 CS1 & CS2 – Implemented in all Nokia BTS without HW change CS3 & CS4 – S11.5 (with PCU2) and UltraSite BTS SW CX4.1 CD1 (Talk is supporting CS1 and CS2) Error Correction Nokia GPRS CS1 PCU1 CS2 Data Coding Payload (bits) Data Rate Scheme per RLC block (kbit/s) More Data = Less Error Correction
    18. 18. GPRS Coding Schemes CS-1 CS-1 CS-3 RLC/MAC Block Size: BCS +4 USF CS-3 181 268 312 Block Check Sequence: MAC CS-2 40 16 16 Precoded USF: 3 6 6 ~2/3 ~3/4 rate a/b convolutional coding 1/2 length: 456 456 bits 57 57 57 57 57 132 57 57 57 Data rate (kbit/s): 9.05 RLC/MAC Block Size: BCS BCS Size: Precoded USF: Data rate (kbit/s): 20 ms 676 220 interleaving MAC USF 588 0 puncturing CS-4 CS-2 13.4 428 16 12 21.4 15.6
    19. 19. EGPR Modulation and Coding Schemes S EGPRS modulation and coding schemes: Scheme Modulation Data rate kb/s MCS-9 MCS-8 MCS-7 59.2 8PSK 54.4 44.8 MCS-6 29.6 27.2 MCS-5 22.4 MCS-4 17.6 MCS-3 GMSK 14.8 13.6 MCS-2 MCS-1 Ref: TS 03.64 11.2 8.8
    20. 20. EGPR Data Treatment Principle in RF Layer S Adding redundancy Puncturing of the coded info User data "Additional info" that does not require extra protection Header part, robust coding for secure transmission
    21. 21. (E)GPRS Mobile Terminal Classes • • • Class C Packet only (or manually switched between GPRS and speech modes) Class B Packet and Speech (not at same time) (Automatically switches between GPRS and speech modes) Class A Packet and Speech at the same time (DTM is subset of class A) BTS BSC
    22. 22. (E)GPRS Multislot Classes Type 1 1 TSL for Measurement Multislot Classes 1-12 Max 4 DL or 4 UL TSL (not atDL same time) UL - Up to 5 TSL shared between UL and DL - Minimum 1 TSL for F Change - 2-4 TSL F Change used when idle measurements required DL Multislot Classes 19-29 UL - Max 8 downlink or 8 uplink (not required at same time) - 0-3 TSL F Change Multislot Classes 30-45 ( Rel-5 ) - Max 5 downlink or 5 uplink (6 shared) Type 2 - Max 6 downlink or 6 uplink (7 shared) Multislot Classes 13-18 - simultaneous receive & transmit - max 8 downlink and 8 uplink (Not available yet, difficult RF design) DL UL 1 TSL for F Change
    23. 23. GPRS implementation • GPRS/EGPRS capable terminals are required • GPRS territory is required in BTS • Packet Control Units (PCUs) need to be implemented in BSCs • Gb interface dimensioning • GPRS packet core network dimensioning • If CS3&CS4 will be implemented following units/items are required • PCU2 with S11.5 BSC SW • Dynamic Abis Pool (DAP) • EDGE capable TRXs • UltraSite and MetroSite BTS SW support
    24. 24. EGPR Implementation S • Can be introduced incrementally to the network where the demand is • EGPRS capable MS • Network HW readiness/upgrade (BTS and TRX) • TRS capacity upgrade ( Abis and Gb! ) • Dynamic Abis EDGE capable TRX, GSM compatible EDGE functionality in the network elements GGSN SGSN BTS Gn BSC A-bis Gb A BTS EDGE capable terminal, GSM compatible 8-PSK coverage GMSK coverage More capacity in interfaces to support higher data usage MSC
    25. 25. Enabling (E)GPRS The steps to create radio network objects Create a BCF Create a BTS Create handover and power control parameters Attach BTS to RAC Enable EGPRS (EGENA/Y) Define GPRS and EGPRS parameters Enable GPRS (GENA/Y) Create a TRX with DAP connection RAC= Routing Area code
    26. 26. Enabling (E)GPRS The steps to enable the (E)GPRS in BSC Create the dynamic Abis pool Disable the GPRS in the cell Lock the BTS Lock the TRX Delete the TRX to be connected to Dynamic Abis pool Create a TRX which uses the dynamic Abis pool All the TRXs that will be using EGPRS in the BTS must be attached to a dynamic Abis pool Unlock the TRX Enable EGPRS in the BTS (EGENA/Y) Enable GPRS in the cell (GENA/Y) Unlock the BTS
    27. 27. Enabling (E)GPRS To be considered: • When the TRX has been created with EDAP defined at BSC and EGPRS feature is enabled, the TRX must be attached to EDAP on the BTS side also not to fail the configuration of BCF • EDAP in BSC must be inside the TSL boundaries defined in the BTS side • When modifying EDAP the size of EDAP in the BTS has to be the same as the size of EDAP in the BSC • Creating, modifying or deleting of EDAP in the BSC will cause a territory downgrade/upgrade procedure to all territories served by the PCU in question • The ongoing EGPRS/GPRS connections will pause and resume immediately • The maximum EDAP size is 12 timeslots • EDAP must be located on the same ET-PCM line as TRX signaling and traffic channels • There are no specific commissioning tests concerning EDAP
    28. 28. (E)GPRS Protocol Architecture Relay IP IP GPRS Bearer User information transfer User information transfer Um APP TCP/UDP IP SNDCP LLC RLC MAC GSM RF MS GGSN Gn Gb Compression, segmentation Ciphering and reliable link RLC BSSGP MAC NW sr GSM RF L1bis BSS L2 L1 Relay SNDCP GTP LLC BSSGP NW sr L1bis Gi USER PAYLOAD UDP IP L2 L1 SGSN GPRS IP Backbone GTP UDP IP L2 L1 GGSN APP TCP/UDP IP L2 L1 FIXED HOST Internet
    29. 29. (E)GPRS Logical Channels GPRS Air Interface Logical Channels CCCH Common Control Channels PCH Paging CH AGCH Access Grant CH RACH Random Access CH Existing GSM Channels (Shared with GPRS Signaling in GPRS Release 1) DCH Dedicated Channels PACCH Packet Associated Control CH PDTCH Packet Data TCH NEW GPRS Channels
    30. 30. Functionality - Content Introduction • Network architecture and Interfaces • Mobile classes • Network Protocols • Multiframe and header structure • Air interface mapping – physical and logical channel Procedures • State and Mobility Management • GPRS Attach/Detach • Routing Area • Session Management (PDP context) • Temporary Block Flow •RLC/MAC Header •TBF Establishment
    31. 31. (E)GPRS Procedures - Content • Mobility Management and State Management • Mobile States • GPRS attach • GPRS detach • Routing Area • Session Management • PDP context activation • Temporary Block Flow • RLC/MAC Header • TBF establishment
    32. 32. GPRS Mobility Management - Mobile States GPRS Attach/De tach READY Timer expiry IDL E MOBILE REACHABLE Timer expiry MS location not known, subscriber is not reachable by the GPRS nw. STANDB Y MS location known to Routing Area level. MS is capable to being paged for pointto-point data. READ Y Packet TX/RX MS location known to cell level. MS is transmitting or has just been transmitting. MS is capable of receiving point-topoint data.
    33. 33. Attach Procedure • The GPRS Attach procedure establishes a GMM context. This procedure is used for the following two purposes: • a normal GPRS Attach, performed by the MS to attach the IMSI for GPRS services only • a combined GPRS Attach, performed by the MS to attach the IMSI for GPRS and non-GPRS services • Attach procedure description • MS initiates by sending Attach Request • If network accepts Attach Request it sends Attach Accept • P-TMSI, RAI • If network does not accept Attach request it sends Attach Rejected • MS responds for Attach Accept message with Attach Complete (only if P-TMSI changes)
    34. 34. Detach Process • GPRS Detach procedure is used for the following two purposes: • a normal GPRS Detach • a combined GPRS Detach (GPRS/IMSI detach, MS originated) • MS is detached either explicitly or implicitly: • Explicit detach: The network or the MS explicitly requests detach. • Implicit detach: The network detaches the MS, without notifying the MS, a configuration-dependent time after the mobile reachable timer (MSRT) expired, or after an irrecoverable radio error causes disconnection of the logical link
    35. 35. Routing Area The Routing Area Update procedure is used for the followings: • a normal Routing Area Update • a combined Routing Area Update • a periodic Routing Area Update • an IMSI Attach for non-GPRS services when the MS is IMSI-attached for GPRS services. • Routing Area (RA) • Subset of one, and only one Location Area (LA) • RA is served by only one SGSN • For simplicity, the LA and RA can be the same • Too big LA/RA increases the paging traffic, while too small LA/RA increases the signaling for LA/RA Update
    36. 36. Routing Area • Bad LA/RA border design can significantly increase the TRXSIG on LA/RA border cells causing the cell-reselection outage to be longer • LA/RA border should be moved from those areas where the normal CSW and PSW traffic is very high
    37. 37. Session Management - Establishing a PDP Context • PDP Context (Packet Data Protocol): Network level information which is used to bind a mobile station (MS) to various PDP addresses and to unbind the mobile station from these addresses after use • PDP Context Activation • • • • Gets an IP address from the network Initiated by the MS Contains QoS and routing information enabling data transfer between MS and GGSN PDP Context Activation and Deactivation should occur within 2 seconds xt Conte PDP st Reque .55 5.131.33 15
    38. 38. PDP Context Activation - 1 Um BTS 1. MS sends "Activate PDP Context Request" to SGSN 2. SGSN checks against HLR PSTN Network BSC HLR/AuC EIR MSC APN= "" Domain Name Server (DNS) 1 Serving . GPRS Support Node (SGSN) GPRS backbone network (IP based) 2 . SS7 Network Access Point Gateway GPRS Support Node (GGSN) Data network (Internet) GPRS INFRASTRUCTU RE Data network (Internet) Access Point Name = Reference to an external packet data network the user wants to connect to
    39. 39. PDP Context Activation - 2 Finding the GGSN Um BTS 3. SGSN gets the GGSN IP address from DNS 4. SGSN sends "Create PDP Context Request" PSTN Network BSC HLR/AuC EIR MSC 3 . Domain Name Server (DNS) to GGSN SS7 Network Serving GPRS Support Node (SGSN) GPRS backbone network (IP based) Access Point 4 . Gateway GPRS Support Node (GGSN) Data network (Internet) Data network (Internet) DNS ( Domain Name System ) = mechanism to map logical names to IP addresses GPRS INFRASTRUCTU RE
    40. 40. PDP Context Activation - 3 Access Point Name refers to the external network the subscriber wants to use Access Point Selection Um BTS PSTN Network BSC HLR/AuC EIR MSC Domain Name Server (DNS) Serving GPRS Support Node (SGSN) GPRS backbone network (IP based) SS7 Network Access Point Gateway GPRS Support Node (GGSN) Data network (Internet) APN= "" Data network (Internet) GPRS INFRASTRUCTU RE
    41. 41. PDP Context Activation - 4 User ( dynamic ) IP address allocated 5. GGSN sends "Create PDP Context Response" back to SGSN Context Activated 6. SGSN sends “Activate PDP Context Accept“ to the MS Um BTS PSTN Network BSC HLR/AuC EIR MSC 6 Serving . Domain Name Server (DNS) SS7 Network GPRS Support Node (SGSN) GPRS backbone network (IP based) Access Point 5 . Gateway GPRS Support Node (GGSN) Data network (Internet) APN= "" Data network (Internet) GPRS INFRASTRUCTU RE
    42. 42. Temporary Block Flow Temporary Block Flow ( TBF ) : • Physical connection where multiple mobile stations can share one or more traffic channels – each MS has own TFI • The traffic channel is dedicated to one mobile station at a time (one mobile station is transmitting or receiving at a time) • Is a one-way session for packet data transfer between MS and BSC (PCU) • Uses either uplink or downlink but not both (except for associated signaling) • Can use one or more TSLs Comparison with circuit-switched: • normally one connection uses both the uplink and the downlink timeslot(s) for traffic In two-way data transfer: • uplink and downlink data are sent PACCH for downlink TBF) below Uplink TBF (+ in separate TBFs - as Downlink TBF (+ PACCH for uplink TBF) BS C PACCH (Packet Associated Control Channel): Similar to GSM CSW SACCH
    44. 44. Multiple Mobiles and Downlink Transmission The TFI included in the Downlink RLC Block header indicates which Mobile will open the RLC Block associated with its TBF TFI3 RLC Data Block TFI2 TFI5 TFI2 MSs BTS
    45. 45. Multiple Mobiles and Uplink Transmission • Several mobiles can share one timeslot • Maximum of 7 Mobiles are queued in the Uplink • Mobile transmissions controlled by USF (Uplink State Flag) sent on DL Uplink State Flag (dynamic allocation) TS 1 TS 2 New MS TS 3 • Mobile with correct USF will transmit in following Uplink block • Timeslot selected to give maximum throughput
    46. 46. Multiple Mobiles and Uplink Transmission The USF included in the Downlink RLC Block header identifies which Mobile will transmit in the following Uplink RLC Block USF = 3 RLC Data Block USF = 3 USF = 2 USF = 1 MSs BTS
    47. 47. (E)GPRS Resource Allocation - Content Territory method • Default and dedicated territory • Free TSLs TSL Allocation • Scheduling with priority based QoS
    48. 48. Territory Method TRX 1 BCCH SDCCH TS TS TS TS TS TS TS TS TS Territory border TRX 2 TS TS TS BCCH = Signaling TS TS TS = CSW Territory TS = Free TSL for CSW TS = (E)GPRS Territory/Additional capacit TS TS = (E)GPRS Territory/ Default capacity = (E)GPRS Territory/Dedicated capacit
    49. 49. EDAP, PCU and Gb Functionality - Content EDAP • Abis vs. Dynamic Abis • Channels carried on EDAP • EDAP limits • Abis PCM structure PCU • PCU procedures • PCU types and limits Gb • Gb protocols • Gb over FR • Gb over IP
    50. 50. BTS Abis Basic Concepts – PCM frame (E1) One 64 kbit/s (8 bits) channel in PCM frame is called timeslot (TSL) One 16 kbit/s (2bits) channel timeslot is Sub-TSL PCM frame has 32 (E1) or 26 (T1) TSLs One Radio timeslot corresponds one 16 kbit/s Sub-TSL (BCCH, TCH/F etc.) and one TRX takes two TSLs from Abis One TRX has dedicated TRXsig of 16, 32 or 64 kbit/s. 48 kbit/s isnot allowed. One BCF has dedicated BCFsig (16 or 64 kbit/s) for O&M Q1-management needed if TRS management under BSC MCB/LCB required if loop topology is used 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 TCH 0 19 TCH 4 20 21 22 23 24 25 TRXsig 26 27 BCFsig 28 29 30 31 BSC Abis MCB TCH 1 TCH 5 LCB TCH 2 TCH 6 TCH 3 TCH 7 Q1-management TRX1
    51. 51. (E)GPRS Dynamic Abis Pool – EDAP Introduction • Fixed resources for signaling and voice • Dynamic Abis pool (DAP) for data • Predefined size 1-12 PCM TSL per DAP • DAP can be shared by several TRXs in the same BCF (and same E1/T1) • Max 20 TRXs per DAP • Max 480 DAPs per BSC • DAP + TRXsig + TCHs have to be in same PCM • UL and DL EDAP use is independent • DAP schedule rounds for each active Radio Block • Different users/RTSLs can use same EDAP SubTSL 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 MCB LCB TCH 0 TCH 4 TCH 0 TCH 4 TCH 0 TCH 4 TCH 1 TCH 5 TCH 1 TCH 5 TCH 1 TCH 5 TCH 2 TCH 6 TCH 2 TCH 6 TCH 2 TCH 6 TCH 3 TCH 7 TCH 3 TCH 7 TCH 3 TCH 7 EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP EDAP TRXsig1 TRXsig3 BCFsig TRXsig2 Q1-management TRX1 TRX2 TRX3 EGPRS pool
    52. 52. Nokia Dynamic Abis Dimensioning - with EGPRS Data Traffic 0 • Fixed master TSL in Abis for all EGPRS air TSL TCH 0 1 • Slave TSL’s (64 k) in EDAP pool for each air 2 TCH 4 3 TCH 0 TSL 4 TCH 4 5 TCH 0 • TRX and for OMU signaling fixed 6 TCH 4 7 TCH 0 • TSL 0 and 31 typically used for signaling 8 TCH 4 • EDAP pool dimensioning considerations 9 TCH 0 10 TCH 4 • Planned throughput in radio interface 11 TCH 0 12 TCH 4  RTSL territory size 13 TRXsig 1  MS multiclass 14 TRXsig 3 15 • Number of TRXs/BTSs connected to DAP TRXsig 5 16 BCFsig 17 • Total number of PCU Abis Sub-TSLs 18 19 EDAP1 • Gb link size 20 EDAP1 • GPRS/EDGE traffic ratio 21 EDAP1 22 23 24 25 26 27 28 29 30 31 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 TCH 1 TCH 5 TCH 1 TCH 5 TCH 1 TCH 5 TCH 1 TCH 5 TCH 1 TCH 5 TCH 1 TCH 5 MCB TCH 2 TCH 6 TCH 2 TCH 6 TCH 2 TCH 6 TCH 2 TCH 6 TCH 2 TCH 6 TCH 2 TCH 6 TRXsig 2 TRXsig 4 TRXsig 6 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 Q1-management LCB TCH 3 TCH 7 TCH 3 TCH 7 TCH 3 TCH 7 TCH 3 TCH 7 TCH 3 TCH 7 TCH 3 TCH 7 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 EDAP1 TRX 1 TRX 2 TRX 3 TRX 4 TRX 5 TRX 6 EGPRS DAP
    53. 53. Packet Control Unit (PCU) - Introduction • BSC plug-in unit that controls the (E)GPRS radio resources, receives and transmits TRAU frames to the BTSs and Frame Relay packets to the SGSN • Implements both the Gb interface and RLC/MAC protocols in the BSS • Acts as the key unit in the following procedures: • (E)GPRS radio resource allocation and management • (E)GPRS radio connection establishment and management • Data transfer • Coding scheme selection • PCU statistics • The first generation PCUs are optimized to meet GPRS requirements, i.e. non real time solutions (QoS classes "Background" and "Interactive“) • The second generation PCUs (PCU2) supports the real time traffic requirements and enhanced
    54. 54. Gb Interface - Introduction • The Gb interface is the interface between the BSS and the Serving GPRS Support Node (SGSN) • Allows the exchange of signaling information and user data • The following units can be found in Gb • Packet Control Unit (PCU) at the BSS side • Packet Processing Unit (PAPU) at the GPRS IP backbone side Gb • Each PCU has its own separate Gb interface to the BSC SGSN SGSN PCU BSS PAPU GPRS
    55. 55. Gb Interface • Allow many users to be multiplexed over the same physical resource • Resources are given to a user upon activity (sending/receiving) • GPRS signaling and user data are sent in the same transmission plane and no dedicated physical resources are required to be allocated for signaling purposes • Access rates per user may vary without restriction Gb from zero data to the maximum possible line rate (e.g., 1 BSC SGSN 984 kbit/s for the available bit rate of an E1 trunk) PCU BSS PAPU GPRS
    57. 57. Frequency Planning Combined interference and noise estimations needed for (E)GPRS link budget Frequency allocation and C/I level • The existing frequency allocation has high impact on EGPRS performance • Loose re-use patterns will provide better performance for all MCSs Data rate and network capacity • EGPRS highest data rates require high C/I, typ > 20dB & 9 • Possibly no extra spectrum for EDGE so efficient use existing spectrum is very important • EGPRS traffic suited to BCCH use - typically the layer C/I. But limited no. of TSLs available on BCCH; may need layer too for MCS-7, 8 of the with highest to use TCH Sensitivity in tighter reuse and higher load • EDGE can utilize tighter reuse schemes and this is beneficial when planning for high load with limited frequency resources • For systems with stringent spectrum constraints, EGPRS can offer good performance even with tight re-use patterns (1/3 or 3/9). Load dependent
    58. 58. Data rate vs. CIR in Time (Field Measurement) Good quality environment 140 25 20 100 15 CIR(dB) Throughput (kbps) 120 80 60 10 40 Data Throughput Application Throughput TEMS-C/I-GMSK Poly. (TEMS-C/I-GMSK) 20 0 5 0 0 10 20 Time (s) 30 40
    59. 59. Data rate vs. CIR in Time (Field Measurement) Average quality environment 120 25 20 80 15 CIR(dB) Throughput (kbps) 100 60 10 40 Data Throughput Application Throughput TEMS-C/I-GMSK Poly. (TEMS-C/I-GMSK) 20 5 0 0 0 10 20 30 40 Time (s) 50 60 70
    60. 60. Data rate vs. CIR in Time (Field Measurement) Worse quality environment 80 Data Throughput Application Throughput TEMS-C/I-GMSK Poly. (TEMS-C/I-GMSK) 70 60 18 16 14 50 12 40 10 30 8 6 20 4 10 2 0 0 0 50 100 Time (s) 150 CIR(dB) Throughput (kbps) 20