pdf_gross.gifGPRS -
Network Optimization & Trouble Shooting

[3-day course, Euro 3,450.- (net) per participant]

backtotop.gifQuality of Service in GPRS-Networks

Course Description

  • What is Quality of Service in GPRS Networks
    • The QoS-Scope of the GPRS Network Operator
    • The QoS-Perception of the End-User
      - Easy Configuration
      - Reachability
      - Service Accessibility
      - Perceived Performance
    • The Relationship between QoS-Profile, QoS-Perception and Perceived Performance
  • Definition of the Perceived Performance
    • Throughput Rate
    • Maximum and Mean Round Trip Time
    • Reasons for the Huge Difference between RTTmean and RTTmax
  • Differences between the Defined QoS-Profile (Rel 98 / Rel 99) and the Perceived Performance
    • Perceived Performance vs. Traffic Classes (Rel. 99)
      - Conversational Applications
      - Streaming Applications
      - Interactive Applications
      - Background Applications
  • Measuring the Perceived Performance
    • Measurements on the R-Interface
    • Measurements on the Gb-Interface
    • Measurements on the Gn- and Gi-Interface
  • Criticality of Performance-Parameters on the GPRS Interfaces
    • R-Interface
    • Air-Interface
    • Abis-Interface
    • Gb-Interface
    • Gn-Interface
  • Performance Leakage within the GPRS Protocol Stack
    • RLCMAC
    • LLC
    • SNDCP
    • IP
    • TCP
    • Relative Performance Leakage
      - Example Calculations
      - The Definition of Key Performance Indicators
    • Measurement Applications
    • Environmental Constraints
    • Timing KPI’s
    • Throughput KPI’s
    • The Definition of Timing KPI’s
      - End-to End Time Measurements
      - Example: RTT-Measurements during an FTP-Upload
      - Intermediate Time Measurements
      -Example: Access Time on Gb- and Abis-Interface

backtotop.gifThe TCP/IP World in Mobile Environment

  • Introducing the IP-Protocol Stack
  • IP-Addresses
    • IP-Address Classes
    • Special IP-Address Notations
    • Determination of the Owner of an IP-Address
  • The Process of IP-Address Allocation
    • The Dynamic Host Configuration Protocol (DHCP)
      - Automatic Allocation
      - Dynamic Allocation
      - Manual Allocation
      - Operation of the DHCP in GPRS
    • Private IP-Addresses
      - Mobile Subscribers entering the Internet
      - Private IP-Address Ranges
    • Using Network Address Translation (NAT) for Interconnection
      - Principles of Network Address Translation
    • Liabilities of NAT
      - IPsec in Transport Mode
      - Streaming Applications
      - Push Services
    • Optimized Use of NAT in GPRS
      - Business and Power Users
      - Standard Users
  • The IP-Header
    • Overview
    • Example of an IP-Header
    • The IP-Header / Octet 1 – 4
    • The TOS- Field (Type of Service)
    • The TOS- Field / Differentiated Services
    • Using Differentiated Services for the Intra-PLMN Backbone
      - Principles
      - Implementation
      - Differentiation of Control Information and User Data with Different QoS
    • The IP-Header / Octet 5 – 8
    • Fragmentation Control in IP
    • The IP-Header / Octet 9 – 20
    • The IP-Header / Octet 21 – N (IP-Options)
  • Details of the Internet Control Message Protocol (ICMP)
    • ICMP-Message Format
    • ICMP-Messages
      - Echo Reply
      - Destination Unreachable
      - Source Quench
      - Redirect
      - Echo Request
      - Router Advertisement
      - Router Solicitation
      - Time Exceeded for a Datagram
      - Parameter Problem on a Datagram
      - Timestamp Request
      - Timestamp Reply
      - Information Request
      - Information Reply
      - Address Mask Request
      - Address Mask Reply
  • Using ICMP for Roundtrip Time (RTT) Measurements in GPRS
    • Use Trace Route to Determine the IP-Address of the 1st Router
      - Ping with 32 Octets of Data (no Segmentation)
      - Ping with 544 Octets of Data (still no Segmentation)
      - Ping with 1000 Octets of Data (Segmentation)
  • Details of the Transmission Control Protocol (TCP)
    • Services of TCP
    • TCP Connection Establishment
      - Example for TCP Connection Establishment
    • TCP Connection Release
      - Example for TCP Connection Release
    • The TCP-Header
      - The TCP-Header / Octet 1 – 12
      - The TCP-Header / Octet 13 – 20
      - The TCP-Header / Octet 21 – n (Options)
    • The Roundtrip Time (RTT) in TCP-Connections
      - Roundtrip Time (RTT) and Retransmission Timeout (RTO)
      - Long Term Behavior of SRTT and RTO
    • Advanced TCP-Features
    • The Nagle Algorithm and Delayed Acknowledgements
    • The Slow Start and Congestion Avoidance Algorithms
      - Introduction
      - Slow Start and Congestion Avoidance in Operation
      - Long Term Characteristics
    • The Ultimate Importance of RTT and CWND for GPRS
      - The formula for calculating SRTT and RTO is tailored for wireline connections
      - In GPRS, the RTT is highly variable and may therefore cause unnecessary retransmissions
      - Slow start memorizes instances when RTT <-> 2 x SRTT
      - RTT variance in GPRS can have many reasons
    • Consequences of the RTT-Variance for the GPRS Performance
      - Example: FTP-Upload at 150 km/h
    • The Fast Retransmit Algorithm
    • The Fast Recovery Algorithm
  • And what about TCP/IP in GPRS?
    • Some Basic Questions
      - How do the various TCP/IP algorithms impact GPRS operation?
      - Can GPRS be considered as a typical Dial-Up Service? (which implicitly requires similar settings)
      - How critical is the high variance of RTT during a GPRS data transfer when it comes to unnecessary retransmissions?
    • The Bandwidth Delay Product
      - Some Example Calculations for GPRS and Dial-Up
      - Consequences for GPRS
      - Performance Improvement through MSS-Adjustment
      - Setting of the Parameter IPMTU in WINDOWS 98
      - Setting of the Parameter DefaultRcvWindow in WINDOWS 98
  • Important Application Protocols
    • Access to Applications -> The Domain Name System (DNS)
    • The Hypertext Transfer Protocol (HTTP)
      - The HTTP-Message Format
      - Operation of the Hypertext Transfer Protocol
      - Download of a given Web Page
    • GPRS Performance Measurements with HTTP
      - Definition of Trigger Points
      - Impact of GPRS Specific Delays on HTTP-Performance
      - Example of an HTTP-Transaction <-> The Request
      - Example of an HTTP-Transaction <-> The Response
    • The File Transfer Protocol (FTP)
      - GPRS Performance Measurements with FTP
      - Example: FTP-Upload
      - Example: FTP-Download
    • Latency Requirements
  • GPRS Dial Up Network Access
    • The Point-to-Point Protocol (PPP) Frame Format
    • Operation of Dial Up Network Access
      - Link Establishment Phase
      - Authentication and Network Layer Setup
      - Link Termination
      - Example for Dial-Up Network Access using the PPP

backtotop.gifEnd-to-End GPRS Operation

  • End-to-End GPRS Operation
  • The GPRS Life Cycle
    • Cell Selection
    • GPRS Attachment
    • PDP-Context Activation
    • PDP-Context Active
    • PDP-Context Deactivation
    • GPRS Detachment
  • GPRS Operation: Mobile Station <-> PCU
    • Resource Allocation in Uplink and Downlink Direction
    • Signaling during Initial Resource Allocation
      - For Uplink Data Transfer
      - For Downlink Data Transfer
    • Concurrent Resource Allocation
    • Uplink and Downlink Resource Release
      - Uplink Resource Release
      - Downlink Resource Release
  • GPRS Operation: PCU <-> SGSN
  • GPRS Operation: SGSN <-> GGSN
  • GPRS Operation: GPRS Mobility Management (GMM)
    • The Ready Timer
    • GMM Procedures
    • Network Operation Modes (NOM)

backtotop.gifOptimization of the GPRS Network Performance

  • Scope of GPRS Network Optimization
    • Optimization of Network Parameters
    • Optimization of Client Settings
      - Optimization of the RLC/MAC-Layer
    • Functions of RLC/MAC
    • Important Procedures and Parameters for Optimization
      - ACCESS_BURST_TYPE
      - Type of Access (One-Phase / Two-Phase)
      - BS_CV_MAX
      - Format of PACK_CTRL_ACK-Messages
      - Network Control Order
      - NON-DRX-Timer
      - PAN_INC, PAN_DEC, PAN_MAX
      - Resource Allocation Methods
      - Timer T3168
      - Timer T319
  • Optimization of the BSSGP- and NS-Layers
    • Functions of BSSGP and NS
    • Important Procedures and Parameters for Optimization
      - Bc and Tc (<-> Frame Relay)
      - Automatic Resumption
      - Flow Control
  • Optimization of the LLC-Layer
    • Functions of LLC
    • Important Procedures and Parameters for Optimization
      - N201 (max. Number of Octets in the Information Field)
      - Encryption
      - N200 (Number of Retransmissions) and T200
  • Optimization of the GMM-Layer
    • Functions of GMM
    • Important Procedures and Parameters for Optimization
      - READY Timer
      - Network Operation Mode (NOM) and T3312
      - Routing Area Size

v1.4

pdf_gross.gif