HSPA systems        Kari AhoSenior Research Scientist  kari.aho@magister.fi
Disclaimer Effort has been put to make these slides as correct as  possible, however it is still suggested that reader co...
Readings related to the subject General readings    WCDMA for UMTS – H. Holma, A. Toskala    HSDPA/HSUPA for UMTS – H. ...
Contents   Introduction   HSDPA   HSUPA   Continuous Packet Connectivity   I-HSPA   Conclusions                     ...
Introduction               5   © 20082008 Magister Solutions Ltd                   5   © Magister Solutions Ltd
High Speed Packet Access (1/3)   There were number of pushing forces to improve the packet data    capabilities of WCDMA ...
High Speed Packet Access (2/3) HSPA features/properties include e.g.    Higher order modulation and coding        Highe...
High Speed Packet Access (3/3)   Link adaptation in downlink       Possibility to adjust the used modulation and coding ...
WCDMA Background and Evolution                                    3GPP Rel 5      3GPP Rel 6         3GPP Rel 73GPP Rel -9...
Questions Why were the packet data capabilities of WCDMA improved  even further? For what kind of services was HSPA orig...
High Speed Downlink Packet Access            (HSDPA)                         11   11 20082008 Magister Solutions Ltd      ...
Introduction to HSDPA (1/2) In Release 99 there basically exists three different methods  for downlink packet data operat...
Introduction to HSDPA (2/2) HSDPA Improvements for packet data performance both in  terms of capacity and practical bit r...
HSDPA channels (1/2) The Release 99 based DCH is the key part of the system –  despite the introduction of HSDPA    Rele...
HSDPA channels (2/2)    in Release 6 an alternative is provided by the Enhanced DCH     (E-DCH) with the introduction of ...
Questions Mention at least purpose to which Rel’99 DCH is used with  HSDPA What kind of handovers are supported with HSD...
Link Adaptation (1/3) UE informs the Node B regularly of its channel quality by  CQI messages (Channel Quality Indicator)...
Link Adaptation (2/3) Adaptive modulation and higher order modulation  (16/64QAM) with HSDPA                             ...
Link Adaptation (3/3) More complex modulation schemes require more energy  per bit to be transmitted than simply going fo...
Fast Retransmissions (1/3)                Rel ‘99                                  HSPARNC                          Retran...
Fast Retransmissions (2/3)            UE                            NodeB                         RNCUser data            ...
Fast Retransmissions (3/3)   Layer 1 signaling indicates the need of retransmission which leads to much    faster round t...
Questions   What is CQI?   What does link adaptation do?   Which entity initiates RLC re-transmissions?   Which entity...
Downlink scheduling (1/5) NodeB has certain amount of users connected to it and it  needs to schedule the different users...
Downlink scheduling (2/5) Round Robin (RR)    Simplest scheduling algorithms    Assigns users in order i.e. handling al...
Downlink scheduling (3/5) Proportional Fair (PF)    Compromise-based scheduling algorithm    Based upon maintaining a b...
Downlink scheduling (4/5)   PF assigning each users a scheduling priority that is inversely    proportional to its antici...
Downlink scheduling (5/5)   In general priority metric for certain user can be defined as follows                        ...
Mobility with HSDPA (1/4) Handovers are roughly tradeoff between two issues    When channel conditions are getting worse...
Mobility with HSDPA (2/4) Even though there is only one serving HS-DSCH cell, the  associated DCH itself can be in soft(e...
Mobility with HSDPA (3/4) HSDPA handover procedure includes following steps    Serving HS-DSCH cell change procedure is ...
Mobility with HSDPA (4/4)   In the case of intra Node B handover, the HARQ processes    (transmissions) and Node B buffer...
Questions How does Round Robin allocate resources for the users? How intra- and inter-Node B handovers differ from each ...
High Speed Uplink Packet Access           (HSUPA)                        34   34 20082008 Magister Solutions Ltd          ...
Introduction to HSUPA (1/2) Roughly three years later when HSDPA was introduced  uplink counterpart of the high speed pac...
Introduction to HSUPA (2/2)    Easier multicode transmissions    Shorter frame size, 10ms mandatory for all HSUPA capabl...
HSUPA channels (1/4) New uplink transport channel - Enhanced Dedicated  Channel (E-DCH)    Supports key HSUPA features s...
HSUPA channels (2/4) From the Release 99 DCH, the dedicated physical control  channel (DPCCH) is unchanged and the need f...
HSUPA channels (3/4) New channel for retransmission control, carries information  in the downlink direction on whether a ...
HSUPA channels (4/4)                       DPCCH      NodeB                         E-DPCCH                               ...
Questions What new features on top of multicodes and shorter frame  sizes do HSUPA offer? Is DCH part of the HSUPA?     ...
Uplink scheduling (1/5) With HSDPA all the cell power can be directed to a single  user for a short period of time    Ve...
Uplink scheduling (2/5)    The shared resource of the uplink is the uplink noise rise(*), or     the total received power...
Uplink scheduling (3/5) Two different scheduling schemes are defined for HSUPA  traffic    Scheduled transmissions contr...
Uplink scheduling (4/5) Scheduled transmissions    The scheduler measures the noise level and decides whether       Add...
Uplink scheduling (5/5)   Depending on possible user priorities given from the RNC, the    scheduler chooses a particular...
Questions What is the shared resource in the uplink if power is in the  downlink? What kind of scheduling possibilities ...
Multicodes with HSUPA (1/2) Even though Rel’99 DCH supports in theory multicode  transmissions in practice only E-DCH can...
Multicodes with HSUPA (2/2)   If the UE could send with fully utilizing multicodes in some    time instant this might not...
Mobility with HSUPA (1/2) HSUPA supports the soft(er) handover procedure similar to  WCDMA Rel’99 The HARQ operation in ...
Mobility with HSUPA (2/2)                     Packet                   reordering                   RNC                   ...
Questions Why does not DCH support multicodes in practice? If UE is in a two-way soft handover how does the HARQ  operat...
Continuous Packet Connectivity            (CPC)                        53   53 20082008 Magister Solutions Ltd            ...
Continuous Packet Connectivity (1/5) Continuous Packet Connectivity (CPC) was released in  Release 7 Designed to improve...
Continuous Packet Connectivity (2/5) Benefits    Connected inactive HSPA users need less resources and create     less i...
Continuous Packet Connectivity (3/5)9 9 D C H w it h 2 0 - m s T T12 .2 k b p s D C H                               I    (...
Continuous Packet Connectivity (4/5) DL discontinuous transmission or Discontinuous Reception  (DRx) cycles allow an idle...
Continuous Packet Connectivity (5/5) HS-SCCH-less HSDPA operation in downlink    Initial transmission of small (VoIP) pa...
VoIP performance with and withoutCPC   In general major performance enhancements visible if circuit switched    voice ove...
Internet HSPA   (I-HSPA)                60   60 20082008 Magister Solutions Ltd                     ©    © Magister Soluti...
I-HSPA (1/3) Internet-HSPA (I-HSPA) aims to provide competitive mobile  internet access with much more simpler network  a...
I-HSPA (2/3)     NodeB /     E-NodeB              SGSN               RNC               GGSNUE                             ...
I-HSPA (3/3)       Re l a s e          e       99 ~2 0 0          m s R ou n d t r i p t i me of 3 2 - B y t e p a c k et2...
Conclusions              64   64 20082008 Magister Solutions Ltd                   ©    © Magister Solutions Ltd
Conclusions (1/2) High Speed Packet Access evolution for WCDMA was  introduced in Release 5 and 6 for downlink and uplink...
Conclusions (2/2) HSPA improved also the performance of delay critical low  bit rate services like VoIP even though it wa...
HSPA vs DCH (basic WCDMA)Feature                        DCH             HSUPA               HSDPAVariable spreading factor...
HSPA Peak Data RatesDownlink HSDPA                                 Uplink HSUPA Theoretical up to 14.4 Mbps              ...
Thank you!kari.aho@magister.fi                       69   69 20082008 Magister Solutions Ltd                            © ...
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Hspa systems 002

  1. 1. HSPA systems Kari AhoSenior Research Scientist kari.aho@magister.fi
  2. 2. Disclaimer Effort has been put to make these slides as correct as possible, however it is still suggested that reader confirms the latest information from official sources like 3GPP specs (http://www.3gpp.org/Specification-Numbering) Material represents the views and opinions of the author and not necessarily the views of their employers Use/reproduction of this material is forbidden without a permission from the author 2 © 2008 Magister Solutions Ltd
  3. 3. Readings related to the subject General readings  WCDMA for UMTS – H. Holma, A. Toskala  HSDPA/HSUPA for UMTS – H. Holma, A. Toskala  3G Evolution - HSPA and LTE for Mobile Broadband - E. Dahlman, S. Parkvall, J. Sköld and P. Beming, Network planning oriented  Radio Network Planning and Optimisation for UMTS – J. Laiho, A. Wacker, T. Novosad  UMTS Radio Network Planning, Optimization and QoS Management For Practical Engineering Tasks – J. Lempiäinen, M. Manninen 3 © 2008 Magister Solutions Ltd
  4. 4. Contents Introduction HSDPA HSUPA Continuous Packet Connectivity I-HSPA Conclusions 4 © 2008 Magister Solutions Ltd
  5. 5. Introduction 5 © 20082008 Magister Solutions Ltd 5 © Magister Solutions Ltd
  6. 6. High Speed Packet Access (1/3) There were number of pushing forces to improve the packet data capabilities of WCDMA even further, e.g.  Growing interest towards rich calls, mobile-TV and music streaming in the wireless domain  Competitive technologies such as WIMAX High Speed Packet Access (HSPA) evolution introduced first downlink counterpart of the evolution called High Speed Downlink Packet Access (HSDPA) in Release 5 Uplink evolution followed later in Release 6 by the name of High Speed Uplink Packet Access (HSUPA) HSPA was originally designed for non-real time traffic with high transmission rate requirements 6 © 2008 Magister Solutions Ltd
  7. 7. High Speed Packet Access (2/3) HSPA features/properties include e.g.  Higher order modulation and coding  Higher throughput and peak data rates  In theory up to 5,8 Mbps in the uplink and 14 Mbps in the downlink without Multiple Inputs and Multiple Outputs (MIMO)  Multiple Inputs and Multiple Outputs (MIMO)  Roughly speaking equals to additional transmitter and receiver antennas  Fast scheduling in the Node B  Possibility to take advantage of channel conditions with lower latency 7 © 2008 Magister Solutions Ltd
  8. 8. High Speed Packet Access (3/3)  Link adaptation in downlink  Possibility to adjust the used modulation and coding scheme according to be appropriate for current radio channel conditions  Improved retransmission capabilities  Newly introduced layer one retransmissions called as Hybrid Automatic Repeat Request (HARQ) => reduced delay  Radio Link Control (RLC) level retransmissions still possible  Shorter frame sizes and thus Transmission Time Intervals (TTI)  With HSDPA 2ms and with HSUPA 10ms and 2ms 8 © 2008 Magister Solutions Ltd
  9. 9. WCDMA Background and Evolution 3GPP Rel 5 3GPP Rel 6 3GPP Rel 73GPP Rel -99 3GPP Rel 4 (HSDPA) (HSUPA) HSPA+ Further 12/99 03/01 03/02 2H/04 06/07 Releases, (LTE)2000 2001 2002 2003 2004 2005 2006 2007 Europe Europe HSDPA HSUPA Japan (pre- (commercial) (commercial) (commercial) commercial) 9 © 2008 Magister Solutions Ltd
  10. 10. Questions Why were the packet data capabilities of WCDMA improved even further? For what kind of services was HSPA originally designed? 10 © 2008 Magister Solutions Ltd
  11. 11. High Speed Downlink Packet Access (HSDPA) 11 11 20082008 Magister Solutions Ltd © © Magister Solutions Ltd
  12. 12. Introduction to HSDPA (1/2) In Release 99 there basically exists three different methods for downlink packet data operation  DCH,  Forward Access Channel (FACH) and  Downlink Shared Channel (DSCH) After the introduction of HSDPA in Release 5 some changes to downlink packet data operations occurred  New High Speed DSCH (HS-DSCH) channel was introduced  DSCH was removed due to lack of interest for implementing it in practical networks 12 © 2008 Magister Solutions Ltd
  13. 13. Introduction to HSDPA (2/2) HSDPA Improvements for packet data performance both in terms of capacity and practical bit rates are based on  The use of link adaptation,  Higher order modulation,  Fast scheduling,  Shorter frame size (or transmission time interval), and  Physical layer retransmission HSDPA does not support DCH features like fast power control or soft handover 13 © 2008 Magister Solutions Ltd
  14. 14. HSDPA channels (1/2) The Release 99 based DCH is the key part of the system – despite the introduction of HSDPA  Release 5 HSDPA is always operated with the DCH DCH with HSDPA  If the service is only for packet data, then at least the signaling radio bearer (SRB) is carried on the DCH  In case the service is circuit-switched then the service always runs on the DCH  With Release 6, signaling can also be carried without the DCH  In Release 5, uplink user data always go on the DCH (when HSDPA is active) 14 © 2008 Magister Solutions Ltd
  15. 15. HSDPA channels (2/2)  in Release 6 an alternative is provided by the Enhanced DCH (E-DCH) with the introduction of high-speed uplink packet access (HSUPA) User data is sent on High Speed Downlink Shared Channel (HS-DSCH) Control information is sent on High Speed Common Control Channel (HS-SCCH) HS-SCCH is sent two slot before HS-DSCH to inform the scheduled UE of the transport format of the incoming transmission on HS-DSCH 15 © 2008 Magister Solutions Ltd
  16. 16. Questions Mention at least purpose to which Rel’99 DCH is used with HSDPA What kind of handovers are supported with HSDPA? 16 © 2008 Magister Solutions Ltd
  17. 17. Link Adaptation (1/3) UE informs the Node B regularly of its channel quality by CQI messages (Channel Quality Indicator) 17 © 2008 Magister Solutions Ltd
  18. 18. Link Adaptation (2/3) Adaptive modulation and higher order modulation (16/64QAM) with HSDPA 16 In sta n ta n e o u s E sN o [d B ] 14 12 10 8 6 4 2 0 Link -2 adaptation 0 20 40 60 80 1 00 1 20 1 40 1 60 Tim e [n u m b e r o f TTIs ] adjusts the 1 6 Q A M 3 /4 mode within 1 6 Q A M 2 /4 few ms based Q P S K 3 /4 on CQI Q P S K 2 /4 Q P S K 1 /4 18 © 2008 Magister Solutions Ltd
  19. 19. Link Adaptation (3/3) More complex modulation schemes require more energy per bit to be transmitted than simply going for transmission with multiple parallel code channels, thus HSUPA benefits more from using multiple codes as PC keeps the signal levels quite good anyway 19 © 2008 Magister Solutions Ltd
  20. 20. Fast Retransmissions (1/3) Rel ‘99 HSPARNC Retransmisson Packet PacketNodeB RLC ACK/NACK RetransmissonUE Layer 1 ACK/NACK  Radio Link Control (RLC) layer ACK/NACKs also possible with HSPA 20 © 2008 Magister Solutions Ltd
  21. 21. Fast Retransmissions (2/3) UE NodeB RNCUser data (Re)transmission RLC RLC (N)ACK MAC-d MAC-hs (Re)transmission Layer1 HARQ (N)ACK 21 © 2008 Magister Solutions Ltd
  22. 22. Fast Retransmissions (3/3) Layer 1 signaling indicates the need of retransmission which leads to much faster round trip time that with Rel ‘99 Retransmission procedure with layer 1 retransmissions (HARQ) is done so that decoder does not get rid of the received symbols if the transmission fails but combines them with new transmissions Retransmissions can operate in two ways:  Identical retransmissions (soft/chase combining)  Non-identical retransmissions (incremental redundancy) 22 © 2008 Magister Solutions Ltd
  23. 23. Questions What is CQI? What does link adaptation do? Which entity initiates RLC re-transmissions? Which entity initiates HARQ re-transmissions? 23 © 2008 Magister Solutions Ltd
  24. 24. Downlink scheduling (1/5) NodeB has certain amount of users connected to it and it needs to schedule the different users for transmission in different fractions of time (Transmission Time Intervals)  Certain fairness for scheduling time for each user should be maintained  Resources should be utilized in optimal manor There exists different ways that users can be scheduled in downlink, e.g.  Round Robin  Proportional Fair 24 © 2008 Magister Solutions Ltd
  25. 25. Downlink scheduling (2/5) Round Robin (RR)  Simplest scheduling algorithms  Assigns users in order i.e. handling all users without priority  Positive sides  Easy to implement  Each user gets served equally  Negative sides  No channel conditions are taken into account and thus resources might be wasted 25 © 2008 Magister Solutions Ltd
  26. 26. Downlink scheduling (3/5) Proportional Fair (PF)  Compromise-based scheduling algorithm  Based upon maintaining a balance between two competing interests  Maximize network throughput i.e. users are served in good channel conditions  Allowing all users at least a minimal level of service 26 © 2008 Magister Solutions Ltd
  27. 27. Downlink scheduling (4/5)  PF assigning each users a scheduling priority that is inversely proportional to its anticipated resource consumption  High resource consumption => low priority 27 © 2008 Magister Solutions Ltd
  28. 28. Downlink scheduling (5/5)  In general priority metric for certain user can be defined as follows d priority = , r  where instantaneous data rate, d, is obtained by consulting the link adaptation algorithm and average throughput, r, of the user is defined and/or updated as follows (1 − a ) * rold + a * d , if user is served r = ,  (1 − a ) * rold , otherwise −1  where a is so called forgetting factor. Hence, a equals the equivalent averaging period in a number of TTIs for the exponential smoothing filter 28 © 2008 Magister Solutions Ltd
  29. 29. Mobility with HSDPA (1/4) Handovers are roughly tradeoff between two issues  When channel conditions are getting worse, handover to better cell should be made so that packets won’t get lost due to poor channel conditions  However, each time when the handover is made, transmission buffers in the Node B are flushed resulting to additional delays from RLC level retransmission or disruption of service When regarding HSDPA, the user can be connected only to one serving HSDPA Node B at the time  Leading to hard handover when the handover between HSDPA Node Bs is required in contrary to DCH soft handover 29 © 2008 Magister Solutions Ltd
  30. 30. Mobility with HSDPA (2/4) Even though there is only one serving HS-DSCH cell, the associated DCH itself can be in soft(er) handover and maintain the active set as in Rel’99 Node B, Serving HSDPA DCH DCH Node B, Part of DCH active set HS-SCCH UE DCH/HSDPA DCH 30 © 2008 Magister Solutions Ltd
  31. 31. Mobility with HSDPA (3/4) HSDPA handover procedure includes following steps  Serving HS-DSCH cell change procedure is initiated when a link in (DCH) active set becomes higher in strength and stays stronger for certain period of time, referred as time-to-trigger  If the condition mentioned above is met then the measurement report is sent from the UE to the Node B, which forwards it to the RNC  If e.g. the admission control requirements are met the RNC can then give the consent for the UE to make the handover by sending so called Signaling Radio Bearer (SRB) (re)configuration message 31 © 2008 Magister Solutions Ltd
  32. 32. Mobility with HSDPA (4/4)  In the case of intra Node B handover, the HARQ processes (transmissions) and Node B buffers can be maintained and thus there is only minimal interruption in data flow  However, with inter Node B handover i.e. between Node Bs, the Node B packet buffers are flushed including all unfinished HARQ processes which are belonging to the UE that is handed off 32 © 2008 Magister Solutions Ltd
  33. 33. Questions How does Round Robin allocate resources for the users? How intra- and inter-Node B handovers differ from each other? 33 © 2008 Magister Solutions Ltd
  34. 34. High Speed Uplink Packet Access (HSUPA) 34 34 20082008 Magister Solutions Ltd © © Magister Solutions Ltd
  35. 35. Introduction to HSUPA (1/2) Roughly three years later when HSDPA was introduced uplink counterpart of the high speed packet access evolution was introduced in Release 6  In 3GPP original name was not HSUPA but Enhanced Dedicated Channel (E-DCH)  The obvious choices for uplink evolution was to investigate the techniques used for HSDPA and, if possible, adopt them for the uplink as well Improvements in HSUPA when compared to Rel’99  Layer 1 Hybrid ARQ (HARQ) i.e. fast retransmissions  Node B based scheduling 35 © 2008 Magister Solutions Ltd
  36. 36. Introduction to HSUPA (2/2)  Easier multicode transmissions  Shorter frame size, 10ms mandatory for all HSUPA capable devices and 2 ms as optional feature HSUPA is not a standalone feature, but requires many of the basic features of the WCDMA Rel’99  Cell selection and synchronization,  random access,  basic power control loop functions,  basic mobility procedures (soft handover), etc. 36 © 2008 Magister Solutions Ltd
  37. 37. HSUPA channels (1/4) New uplink transport channel - Enhanced Dedicated Channel (E-DCH)  Supports key HSUPA features such as HARQ, fast scheduling etc.  Unlike HS-DSCH (HSDPA) E-DCH is not a shared channel, but a dedicated channel (*)  Similarly to DCH, E-DCH is also mapped to physical control and data channels  The user data is carried on the enhanced dedicated physical data channel (E-DPDCH) while new control information is on the E- DPCCH (*)Dedicated channel means that each UE has its own data path to the Node B that is continuous and independent from the DCHs and E-DCHs of other UEs 37 © 2008 Magister Solutions Ltd
  38. 38. HSUPA channels (2/4) From the Release 99 DCH, the dedicated physical control channel (DPCCH) is unchanged and the need for the DPDCH depends on possible uplink services mapped to the DCH  DPCCH is used e.g. for fast power control New channels for scheduling control  E-DCH absolute grant channel (E-AGCH) - absolute scheduling value  E-DCH relative grant channel (E-RGCH) - relative step up/down scheduling commands 38 © 2008 Magister Solutions Ltd
  39. 39. HSUPA channels (3/4) New channel for retransmission control, carries information in the downlink direction on whether a particular base station has received the uplink packet correctly or not  E-DCH HARQ indicator channel (E-HICH) 39 © 2008 Magister Solutions Ltd
  40. 40. HSUPA channels (4/4) DPCCH NodeB E-DPCCH E-DPDCH E-RGGH UE E-AGCH E-HICH 40 © 2008 Magister Solutions Ltd
  41. 41. Questions What new features on top of multicodes and shorter frame sizes do HSUPA offer? Is DCH part of the HSUPA? 41 © 2008 Magister Solutions Ltd
  42. 42. Uplink scheduling (1/5) With HSDPA all the cell power can be directed to a single user for a short period of time  Very high peak data rates achievable for certain UE and all the others can be left with a zero data rate  However, in the next time instant another UE can be served and so on With HSUPA HSDPA type of scheduling is not possible  HSUPA is a many-to-one scheduling  The uplink transmission power resources are divided to separate devices (UEs) which can be used only for their purposes and not shared as with HSDPA 42 © 2008 Magister Solutions Ltd
  43. 43. Uplink scheduling (2/5)  The shared resource of the uplink is the uplink noise rise(*), or the total received power seen in the Node B receiver  Typically, one UE is unable to consume that resource alone completely and it is very beneficial for the scheduler to know at each time instant how much of that resource each UE will consume and to try to maintain the interference level experienced close to the maximum  Thus, HSUPA scheduling could be referred as very fast DCH scheduling(*)ratio between the total power received from all of the UEs at the base station andthe thermal noise 43 © 2008 Magister Solutions Ltd
  44. 44. Uplink scheduling (3/5) Two different scheduling schemes are defined for HSUPA traffic  Scheduled transmissions controlled by Node B which might not guarantee high enough minimum bit rate. In addition each request requires time consuming signaling  Non-scheduled transmissions (NST) controlled by radio network controller (RNC) which defines a minimum data rate at which the UE can transmit without any previous request. This reduces signaling overhead and consequently processing delays 44 © 2008 Magister Solutions Ltd
  45. 45. Uplink scheduling (4/5) Scheduled transmissions  The scheduler measures the noise level and decides whether  Additional traffic can be allocated  Should some users have smaller data rates  The scheduler also monitors the uplink feedback  Transmitted on E-DPCCH in every TTI  Referred as happy bits  Tells which users could transmit at a higher data rate both from the buffer status and the transmission power availability point of view 45 © 2008 Magister Solutions Ltd
  46. 46. Uplink scheduling (5/5)  Depending on possible user priorities given from the RNC, the scheduler chooses a particular user or users for data rate adjustment  The respective relative or absolute rate commands are then send on the E-RGCH or E-AGCH  UE in soft handover receives only relative hold/down commands from other than serving HSUPA Node B 46 © 2008 Magister Solutions Ltd
  47. 47. Questions What is the shared resource in the uplink if power is in the downlink? What kind of scheduling possibilities HSUPA offer? 47 © 2008 Magister Solutions Ltd
  48. 48. Multicodes with HSUPA (1/2) Even though Rel’99 DCH supports in theory multicode transmissions in practice only E-DCH can support multicode transmissions and thus higher bitrates  In theory DCH can use 6xSF4 leading to 5.4 Mbps  E-DCH can in practice support 2xSF2 + 2xSF4 leading to 5.4 Mbps The reason why DCH does not support multicodes is that the DCH is controlled by RNC and thus DCH is rather slowly controllable 48 © 2008 Magister Solutions Ltd
  49. 49. Multicodes with HSUPA (2/2)  If the UE could send with fully utilizing multicodes in some time instant this might not be the case later and UE might end up in power outage and thus wouldn’t be able to use its allocation  With RNC control reallocation of resources is slow => resources wasted  Also, HSUPA with HARQ increases the possibility to operate with higher BLER target which leads to lower power requirement for corresponding data rate 49 © 2008 Magister Solutions Ltd
  50. 50. Mobility with HSUPA (1/2) HSUPA supports the soft(er) handover procedure similar to WCDMA Rel’99 The HARQ operation in HSUPA soft handover situation is done in following manor  If any Node B part of the active set sends an ACK, then the information given to the Medium Access Control (MAC) layer is that an ACK has been received and the MAC layer will consider the transmission successful 50 © 2008 Magister Solutions Ltd
  51. 51. Mobility with HSUPA (2/2) Packet reordering RNC Correctly NodeB received Layer 1 packet ACK/NACK Data NodeB UE Layer 1 ACK/NACK 51 © 2008 Magister Solutions Ltd
  52. 52. Questions Why does not DCH support multicodes in practice? If UE is in a two-way soft handover how does the HARQ operate? 52 © 2008 Magister Solutions Ltd
  53. 53. Continuous Packet Connectivity (CPC) 53 53 20082008 Magister Solutions Ltd © © Magister Solutions Ltd
  54. 54. Continuous Packet Connectivity (1/5) Continuous Packet Connectivity (CPC) was released in Release 7 Designed to improve the performance of delay critical small bit rate services like VoIP Eliminates the need for continuous transmission and reception when data is not exchanged. Can be categorized into three feature  UL discontinuous transmission  DL discontinuous transmission  HS-SCCH less for HSDPA VoIP 54 © 2008 Magister Solutions Ltd
  55. 55. Continuous Packet Connectivity (2/5) Benefits  Connected inactive HSPA users need less resources and create less interference => more users can be connected  UE power savings => increased talk time (VoIP)  UTRAN resources are saved 55 © 2008 Magister Solutions Ltd
  56. 56. Continuous Packet Connectivity (3/5)9 9 D C H w it h 2 0 - m s T T12 .2 k b p s D C H I (Re l 9 , C S v o ic e ) ’9 32 k b p s E -D CH- D C H w it h 10 - m s T T I(Re l , p h a s e 1, Vo I P ) ’6 16 0 k b p s E - D C H- D C H w it h 2 - m s T T I Po w e r o f f s e tRe l 6 , p h a s e 2 , Vo I P ) - 16 0 k b p s E - D C HE - D C H w it h 2 m s T T I POa n d U L D P C C H g a t in g (Re l 7 , Vo I P ) - = D P D C H (D C H ) / E - D P D C H (E - D C H ) = D PCCH 56 © 2008 Magister Solutions Ltd
  57. 57. Continuous Packet Connectivity (4/5) DL discontinuous transmission or Discontinuous Reception (DRx) cycles allow an idle UE to power off the radio receiver for a predefined period  Period after the UE wakes up again is called as DRx cycle  When UE wakes up it listens predefined time for incoming transmissions and if it successfully decodes a new transmission during that time it starts timer for staying active certain period of time No m e as u r e m e n On Duration DRX PeriodUE shall monitor t s done or PDCCH d at a r e c e iv e d DRX Cycle 57 © 2008 Magister Solutions Ltd
  58. 58. Continuous Packet Connectivity (5/5) HS-SCCH-less HSDPA operation in downlink  Initial transmission of small (VoIP) packets can be sent without High Speed Secondary Control Channel (HS-SCCH)  Eliminates the control channel overhead from small packets sent over HSDPA  Retransmissions are sent with HS-SCCH pointing to the initial transmission 58 © 2008 Magister Solutions Ltd
  59. 59. VoIP performance with and withoutCPC In general major performance enhancements visible if circuit switched voice over WCDMA and VoIP over HSPA Rel 7 is compared  With Rel 99 CS voice capacity 60-70 users/cell  With Rel 7 VoIP capacity goes beyond 120 users/cell H. Holma, M. Kuusela, E. Malkamäki, K. Ranta-aho, C. Tao: “VoIP over HSPA with 3GPP Release 7”, PIMRC, 2006. 59 © 2008 Magister Solutions Ltd
  60. 60. Internet HSPA (I-HSPA) 60 60 20082008 Magister Solutions Ltd © © Magister Solutions Ltd
  61. 61. I-HSPA (1/3) Internet-HSPA (I-HSPA) aims to provide competitive mobile internet access with much more simpler network architecture than it is in normal WCDMA systems Deployable with existing WCDMA base stations Utilizes standard 3GPP terminals Simplified architecture brings many benefits such as  Cost-efficient broadband wireless access  Improves the delay performance  Transmission savings  Enables flat rating for the end user  Works anywhere (compared to WLAN or WIMAX) 61 © 2008 Magister Solutions Ltd
  62. 62. I-HSPA (2/3) NodeB / E-NodeB SGSN RNC GGSNUE Internet / Intranet I-HSPA 62 © 2008 Magister Solutions Ltd
  63. 63. I-HSPA (3/3) Re l a s e e 99 ~2 0 0 m s R ou n d t r i p t i me of 3 2 - B y t e p a c k et20018 0 HS D PA <10 0 m s16 0 HS U PA Internet14 0 ~5 0 Iu + core12 0 ms RNC I -HS PA Iub10 0 ~2 5 Node B80 ms AI60 UE4020 0 T o d ay HS D P A HS D P A+ HS U P A I - HS D P A+ I - HS U P A 63 © 2008 Magister Solutions Ltd
  64. 64. Conclusions 64 64 20082008 Magister Solutions Ltd © © Magister Solutions Ltd
  65. 65. Conclusions (1/2) High Speed Packet Access evolution for WCDMA was introduced in Release 5 and 6 for downlink and uplink, respectively HSPA offers much higher peak data rates, reaching in theory up to 14 Mbps in the downlink and 5,4 Mbps in the uplink, in addition to reduced delays Key technologies with HSPA are  Fast Layer 1 retransmissions i.e. HARQ  Node B scheduling  Shorter frame size (2ms in DL and 2/10ms UL)  Higher order modulation and coding along with link adaptation in downlink  Real support for multicodes in the uplink 65 © 2008 Magister Solutions Ltd
  66. 66. Conclusions (2/2) HSPA improved also the performance of delay critical low bit rate services like VoIP even though it was not originally designed for it Continuous Packet Connectivity (CPC) enhancements introduced in Release 7 improved VoIP performance even more I-HSPA was introduced to provide competitive internet access solution  High data rates with low delay  Reduced costs => flat rate could be possible Femtocells were introduced to improve the mobile convergence and performance in small offices or at home, for instance 66 © 2008 Magister Solutions Ltd
  67. 67. HSPA vs DCH (basic WCDMA)Feature DCH HSUPA HSDPAVariable spreading factor Yes Yes NoMulticode transmission Yes Yes Yes (No in practice)Fast power control Yes Yes NoSoft handover Yes Yes No (associated DCH only)Adaptive modulation No No YesBTS based scheduling No Yes YesFast L1 HARQ No Yes Yes 67 © 2008 Magister Solutions Ltd
  68. 68. HSPA Peak Data RatesDownlink HSDPA Uplink HSUPA Theoretical up to 14.4 Mbps  Theoretical up to 5.76 Mbps Initial capability 1.8 – 3.6 Mbps  Initial capability 1.46 Mbps M ax M ax # of c od M od u l a t i on es # of c od es T T I dat a r at e dat a r at e 5 cod e s Q PS K 1.8 M b p s 2 ms 2 x SF4 1.4 6 M b p s 10 m s 5 cod e s 16 - Q AM 3 .6 M b p s 2 x SF2 10 m s 2 .0 M b p s 10 c o d e s 16 - Q AM 7 .2 M b p s 2 x SF2 2 ms 2 .9 M b p s 15 c o d e s 16 - Q AM 10 .1 M b p s 2 x SF2 + 2 ms 5 .7 6 M b p s 2 x SF4 15 c o d e s 16 - Q AM 14 .4 M b p s 68 © 2008 Magister Solutions Ltd
  69. 69. Thank you!kari.aho@magister.fi 69 69 20082008 Magister Solutions Ltd © © Magister Solutions Ltd
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