A-GPS: Assisted GPS, GNSS, and SBAS

✍ Scribed by Frank van Diggelen

• Publisher: Artech House
• Year: 2009
• Tongue: English
• Leaves: 400
• Edition: 1
• Category: Library

✦ Synopsis

Assisted GPS (A-GPS) has been developed to provide greatly improved capabilities, helping GPS work better and faster in almost any location. Offering a detailed look at all the technical aspects and underpinnings of A-GPS, this unique book places emphasis on practical implementation. The book reviews standard GPS design, helping you understand why GPS requires assistance in the first place. You discover how A-GPS enables the computing of a position from navigation satellites in the absence of precise time a topic not covered in any other book. Moreover, you learn how to design and analyze a high sensitivity GPS receiver and determine the achievable sensitivity. The book provides detailed worksheets that show how to compute, analyze, and improve the processing gain from the input signal at the antenna to the signal after the correlators. These worksheets are used in the book to generate families of curves that completely characterize receiver sensitivity, parameterized in terms of front end noise figure, coherent and noncoherent integration times. From this work a law of achievable sensitivity is derived and explained in the book. This cutting-edge volume discusses special forms of assistance data, industry standards for A-GPS, and government mandates for location of mobile phones. You also find coverage of future global navigation satellite systems and how they can be designed specifically for instant-fixes and high sensitivity. The book features numerous tables, worksheets, and graphs that illustrate key topics and provide the equivalent of a technical handbook for engineers who design or use A-GPS.

✦ Table of Contents

A-GPS: Assisted GPS, GNSS, and SBAS......Page 2
Contents......Page 6
Foreword......Page 14
Preface......Page 16
Acknowledgments......Page 18
1.1 A-GPS Overview......Page 20
1.2 Book Structure......Page 22
1.3 Civilian Signals......Page 23
1.5 Terminology: A-GPS, A-GNSS......Page 24
1.7 What’s New?......Page 25
References......Page 26
2.1 Overview: How GPS Was Designed to Work......Page 28
2.2 GPS Signal Power......Page 29
2.3 Satellite Orbits......Page 31
2.4 Satellite Clocks......Page 38
2.5 Ephemeris......Page 41
2.6 GPS Signals......Page 42
2.7 Basic GPS Receiver Functions......Page 45
2.7.1 Mixers......Page 46
References......Page 48
3.1.2 Quantitative Overview......Page 50
3.1.3 Cold, Warm, and Hot Starts......Page 52
3.1.4 Assistance......Page 53
3.2 Frequency and Code-Delay Search Space......Page 54
3.2.1 Satellite Motion......Page 55
3.2.3 Receiver Oscillator Offset......Page 56
3.3.1 Hardware and Software Receivers, Sequential and Parallel Searches......Page 57
3.3.3 Typical Acquisition Scheme, Autonomous Cold Start......Page 58
3.4 Tracking, Reacquisition, and Assistance......Page 61
3.5 MS-Assisted and MS-Based GPS......Page 62
3.6.1 MS-Based Frequency Assistance......Page 63
3.6.3 Assistance Frequency Error Analysis: Time......Page 64
3.6.4 Assistance-Frequency Error Analysis: Reference Frequency and Speed......Page 65
3.6.5 Assistance Frequency Error Analysis: Position......Page 66
3.7 A-GPS Time Assistance for Code Delay......Page 68
3.7.1 MS-Based Fine-Time Assistance......Page 69
3.7.4 Code-Delay Assistance Error Analysis: Position......Page 70
3.7.5 Code-Delay Assistance Error Analysis: Almanac or Ephemeris......Page 73
3.8.1 Coarse-Time, Frequency Search......Page 74
3.8.2 Fine-Time, Code-Delay Search......Page 76
3.8.3 Coarse-Time, Code-Delay Search......Page 78
References......Page 79
4.1.1 Precise and Coarse Time in Navigation......Page 80
4.1.2 Chapter Outline......Page 82
4.2 Navigation, Algebraic Description......Page 83
4.3 Navigation Equations with Coarse Time......Page 86
4.4 Millisecond Integers and Common Bias......Page 90
4.4.1 Examples of the Effect of Common Bias......Page 92
4.4.2 Solving for Millisecond Integer Ambiguity......Page 100
4.5.2 Satellite Clock Error......Page 116
4.5.3 Coordinate Systems......Page 117
4.5.4 Pseudomeasurements......Page 118
4.5.5 Practical Considerations......Page 119
References......Page 120
5.1.1 HDOP and Accuracy......Page 122
5.2 Extra-State Theorem......Page 124
5.2.1 Special Case of GDOP......Page 125
5.2.2 Positive Definite and Semidefinite Matrices......Page 126
5.2.3 General Case for Any DOP......Page 127
5.2.4 Equivalence......Page 128
5.2.5 Upper Bound......Page 133
5.3.1 3GPP Standardized Scenarios......Page 134
5.3.2 GPS Constellation (30 Satellites)......Page 142
5.3.3 GNSS Constellation (60 Satellites)......Page 144
References......Page 145
6.1 Overview......Page 146
6.1.1 Chapter Outline......Page 150
6.2 Standard GPS Receiver Architecture......Page 151
6.3 Front-End Analysis......Page 152
6.3.1 Front-End Worksheet......Page 155
6.3.3 dBm and dB-Hz......Page 156
6.3.4 Sky Noise and Simulator Noise......Page 158
6.4.1 Correlation and Ideal Coherent Integration......Page 159
6.4.2 Implementation Losses......Page 163
6.4.3 SNR Worksheet......Page 177
6.5 High-Sensitivity Receiver Architecture......Page 179
6.5.1 Counting Correlators......Page 180
6.5.2 Correlator Size Versus Integration Time......Page 181
6.6 Longer Coherent Integration Times......Page 182
6.6.2 Data Bit Alignment......Page 183
6.6.3 Maximum Frequency Error Versus Coherent-Integration Time......Page 186
6.6.4 Maximum Velocity Versus Coherent-Integration Time......Page 187
6.7.1 I,Q Channels......Page 190
6.7.2 RSS and Squaring Loss......Page 191
6.7.3 Deriving the Squaring Loss Analytically......Page 194
6.7.4 Evaluating the Squaring Loss Experimentally......Page 199
6.7.5 Noncoherent Integration......Page 203
6.8.1 Coarse-Time Acquisition......Page 205
6.8.2 Coherent Interval and Frequency Bins......Page 206
6.8.3 Fine-Time Acquisition and Tracking......Page 210
6.8.4 Detection Thresholds, PFA and PD......Page 212
6.8.5 Achievable Sensitivity Plots......Page 220
6.8.6 Sensitivity Versus Correlator Size......Page 225
6.9.1 Hardware and Software Approaches......Page 227
6.9.2 Technology Evolution......Page 230
6.9.3 Signal Strengths in Practice and Attenuation Through DifferentMaterials......Page 234
6.9.4 Multipath and Pure Reflections......Page 236
6.9.6 Testing the SNR Worksheet with Real Signals......Page 238
References......Page 240
7.1 Overview......Page 244
7.1.1 Chapter Outline......Page 246
7.2 Reference Stations......Page 247
7.3.1 Public Reference Networks......Page 248
7.3.2 Proprietary Commercial Reference Networks......Page 249
7.3.3 Benefits of a Worldwide Reference Network......Page 252
7.4 Initial Position in Assistance Data......Page 255
7.5.2 Orbit Data......Page 256
References......Page 257
8.1 Overview: Assistance When There Is No Assistance......Page 258
8.1.1 Chapter Outline......Page 261
8.2 Generating Ephemeris Extensions......Page 262
8.2.1 Using a Worldwide Reference Network—One Week of Orbits......Page 263
8.2.2 Using a Worldwide Reference Network and Ephemeris Decoded at a Mobile Device—One Month of Orbits......Page 268
8.2.3 Using Only Ephemeris Decoded at a Mobile Device—Daily Repeat of Orbits......Page 269
8.2.4 Comparing Accuracy Metrics......Page 271
8.2.5 Ephemeris Extension Accuracy Summary......Page 273
8.3 Enhanced Autonomous Using Ephemeris Extensions in Place of Full A-GPS Assistance......Page 275
8.3.1 Computing Position from Doppler Measurements......Page 277
8.3.2 Computing Position from a Mix of Doppler and Full Pseudorange Measurements......Page 287
8.4 Integrity Monitoring—Dealing with Changes in Orbits and Clocks......Page 288
8.4.2 Monitoring Broadcast Ephemeris......Page 289
References......Page 290
9.1.1 Positioning Methods, Method Types, and Location Requests......Page 294
9.1.2 Industry Standards Organization......Page 297
9.1.4 De Facto Standards: ME-PE, MEIF......Page 299
9.2.1 GSM-RRLP Protocol Specification......Page 300
9.2.3 Other Relevant 3GPP Standards......Page 301
9.4 OMA-SUPL......Page 302
9.5.1 3GPP......Page 303
9.5.2 3GPP2......Page 305
9.6.2 ME-PE Architecture......Page 307
9.6.3 Nokia ME Interface (MEIF)......Page 309
9.7.1 E911—United States......Page 310
9.7.2 E112—Europe......Page 312
References......Page 313
10.1 Overview......Page 316
10.1.1 Chapter Outline......Page 317
10.2.1 One Millisecond, 1023 Chip, PRN Code......Page 318
10.2.2 The Twenty Millisecond Data Bit Period......Page 319
10.2.3 Continuous Reference Time (No Leap Seconds)......Page 321
10.2.4 CDMA on the Same Frequency......Page 322
10.3 Future A-GNSS Features for TTFF, Sensitivity, and Accuracy......Page 323
10.3.1 Fast TTFF......Page 327
10.3.2 High Sensitivity......Page 329
10.3.3 Accuracy......Page 334
References......Page 342
A.2 Deriving the Navigation Equations from First Principles......Page 344
A.2.1 Deriving the Inner Product......Page 345
A.2.2 Analyzing the Linearization Error......Page 347
A.3 Deriving the Navigation Equations with Partial Derivatives......Page 348
A.4 Deriving the Coarse-Time Navigation Equations with Partial Derivatives......Page 351
A.5 Writing H in NED Coordinates......Page 352
B.2 Alternative Proof of Extra State Theorem......Page 354
References......Page 356
C.2 Rayleigh and Rice Distributions......Page 358
References......Page 360
D.1 GPS Almanac......Page 362
D.2 SBAS Almanac......Page 363
D.3 GLONASS Almanac......Page 364
D.5 Compass Almanac......Page 365
D.6 QZSS Almanac......Page 366
References......Page 368
Appendix E Conversion Factors, Rules of Thumb, and Constants......Page 370
Glossary......Page 374
Algebraic Conventions......Page 379
Signal-Processing Variables and Notation......Page 380
Clock Parameters for GPS......Page 382
About the Author......Page 384
Index......Page 386