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Edge Seminar


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Edge Seminar

  1. 1. By: SKANDA<br />Electronics and Communication Dept.<br />NMAM Institute of Technology<br />8/9/2010<br />1<br />
  2. 2. Introduction of EDGE<br />Necessary Technologies to support EDGE<br />Upgrading GSM to EDGE<br />The Transmission techniques behind EDGE<br />The Technology of EDGE<br />Benefits<br />Future of EDGE<br />Question and Answer Session<br />8/9/2010<br />2<br />
  3. 3. EDGE stands for Enhanced Data rates for GSM(or Global) Evolution. It is also called as Enhanced GPRS.<br />EDGE is a high-speed mobile data standard. This technology gives GSMthe capacity to match the services offered by 3G network.<br />EDGE is considered as a 2.75 generationstandard that is seen as a transition from 2G to 3G.<br />8/9/2010<br />3<br />
  4. 4. EDGE allows data transmission speeds up to 473.6 Kbps.<br />The idea behind EDGE is to increase the data rate that can be achieved with GSM by changing the type of modulation used while still working with existing GSM and GPRS network.<br />EDGE devices are backwards compatible with GPRS and will be able to operate on GPRS networks where EDGE has not yet been deployed. <br />EDGE deployment began in 2003. Initially in North America <br />8/9/2010<br />4<br />
  5. 5. GSM (Global System for Mobile Comm.):<br />Is the largest mobile standard in use today used in over 200 countries. More than 70 percent of the world's mobile phones operate on GSM.<br />GSM users enjoy worldwide roaming.<br />GSM is implemented in, 800MHz, 900MHz, 1800MHz and 1900MHz frequency bands. <br />8/9/2010<br />5<br />
  6. 6. 2. GPRS (General Packet Radio Service): <br />An enhancement for GSM networks that introduces packet data transmission. <br />GPRS uses radio spectrum very efficiently and provides users with "always on" connectivity and greater bandwidth. It uses Gaussian minimum shift keying.<br />GPRS delivers speeds of up to 115kbps.<br />8/9/2010<br />6<br />
  7. 7. If GPRS is already in place in a network, EDGE technology requires software upgrades and EDGE plug-in transceiver.<br />EDGE transceivers used in cell phones are SMARTi®PM 2+, MMM7010.<br />The additional modulation that is introduced is the eight-state phase-shift keying (8-PSK).<br />8/9/2010<br />7<br />
  8. 8. Problem with GPRS!<br />In cellular system different users tend to have different channel qualities in terms of signal-to-interference ratio (ratio of the average received modulated carrier power to the average received co-channel interference power I), due to differences in distance to the base station, fading, and interference.<br />Services such as speech requires a certain target SIR to give good quality, below the target the quality is unacceptable, while above the target the quality is good and practically independent of channel quality.<br />Thus network has to make sure that only a small fraction of users are below the SIR target. But large part of the user population will then experience unnecessarily high SIR (i.e. excellent channel quality from which they cannot benefit). <br />EDGE is designed to improve the situation by employing the mechanism known as link quality control.<br />8/9/2010<br />8<br />
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  10. 10. Link quality control adapts so that for all channel qualities an optimal bit rate is obtained. <br />Standard GPRS saturates at low SIR, whereas EDGE user quality increases with increased channel quality.<br />To obtain this characteristics EDGE must include transmission modes with significantly higher information bit rates than those of standard GSM. <br />This is the reason for the introduction of the new modulation, 8-PSK, which is the core of the EDGE.<br />8/9/2010<br />10<br />
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  12. 12. Main new network architecture entities that are needed for the EDGE upgrade are<br />SGSN:  <br />This forms a gateway to the services within the network. It provides a variety of services to the mobiles like Packet routing and transfer, Authentication, Logical link management ,Charging data. <br />There is a location register within the SGSN and this stores location information.<br />GGSN:  <br />It can be considered to be a combination of a gateway, router and firewall as it hides the internal network to the outside. <br />GGSN receives data addressed to a specific user, it checks if the user is active, then forwards the data. Similarly packet data from the mobile is routed to the right destination network by the GGSN.<br />PCU:<br />It differentiates data destined for the GSM network (circuit switched data) and data destined for the EDGE network (Packet Switched Data).<br />8/9/2010<br />12<br />
  13. 13. GMSK: <br />Gaussian minimum shift keying is a continuous-phase frequency-shift keying modulation scheme. It is similar to minimum-shift keying (MSK); but the digital data stream is first shaped with a Gaussian filter before being applied to a frequency modulator.<br />MSK uses changes in phase to represent 0's and 1's. <br />The pulse sent to represent a 0 or 1, not only depends on what information is being sent, but what was previously sent. <br />8/9/2010<br />13<br />
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  16. 16. <ul><li>Why GMSK is Used?</li></ul>Gaussian filter reduces sideband power, which in turn reduces out-of-band interference between signal carriers in adjacent frequency channels.<br />GMSK has high spectral efficiency<br /> It has a constant power level which allows higher efficiency RF power amplifiers to be used in the handset, thereby reducing current consumption and conserving battery life. <br />None of the information is carried as amplitude variations. This means that it is immune to amplitude variations and therefore more resilient to noise, than some other forms of modulation, because most noise is mainly amplitude based.<br />8/9/2010<br />16<br />
  17. 17. Drawbacks of GMSK<br />Gaussian filter increases the modulation memory in the system and causes inter symbol interference, making it more difficult to discriminate between different transmitted data values and requiring more complex channel equalization algorithms.<br />8/9/2010<br />17<br />
  18. 18. 2. 8-PSK Modulation<br />In 8-PSK modulation the information is conveyed on the phase of the carrier.<br />8/9/2010<br />18<br />
  19. 19. Steps:<br />The mapping of the bits onto the symbols of the constellation produces one of the two symbols, +1 and –1.<br />A rotation of 3π/8 radians per symbol is applied on the resulting signal.<br />The symbols are filtered by the Gaussian pulse.<br />The resulting signal is very similar to the GMSK in the sense that each +1 symbol results in a phase shift of 3π/8, and each –1 symbol results in a –3π/8 phase shift, whereas with GMSK a ± 1 results in a ± π/2 phase rotation. This difference between the two modulation signals is used in the channel estimation stage of the receiver <br />8/9/2010<br />19<br />
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  21. 21. Advantages of PSK <br />Operates within the existing GSM / GPRS channel structure. <br />Able to operate within the existing GSM channel bandwidth. <br />Able to operate within the existing GSM / GPRS channel coding structure. <br />An 8-PSK signal is able to carry 3 bits per modulated symbol over the radio path, while a GMSK signal carries only 1 bit per symbol<br />8/9/2010<br />21<br />
  22. 22. GMSK&8-PSK works together<br />PSK has the equivalent bandwidth and adjacent channel interference levels to GMSK. This makes it possible to integrate EDGE channels into the existing GSM / GPRS network. <br />Using 8-PSK, the rate at which symbols are sent remains the same. However each symbol now represents three bits instead of one. This means that the actual data rate is increased by a factor of three. <br />when the signal is poor GMSK can be more effective than 8PSK, and as a result, the overall EDGE modulation scheme is a mixture of GMSK and 8PSK <br />8/9/2010<br />22<br />
  23. 23. Modulation & Coding Schemes<br />Throughput Associated with Modulation and Coding Schemes for GPRS&EDGE<br />8/9/2010<br />23<br />
  24. 24. The different coding schemes are grouped into 3 Classes which are referred to by letters, as classes A, B and C. The coding Schemes within a class are used together and complement each other. <br />Family A consists of MCS-3, MCS-6, MCS-8, and MCS-9. <br />Family B consists of MCS-2, MCS-5, and MCS7. <br />Family C consists of MCS-1, and MCS- 4. <br />If a block transmitted in one of the coding schemes is not acknowledged, then it can be sent as two blocks, with a coding scheme in the same family. <br />Example:if a block transmitted using MCS-7 is corrupted then it can be re-sent as two blocks using MCS-5 or four using MCS2.<br />8/9/2010<br />24<br />
  25. 25. EDGE, GPRS and GSM have to all operate alongside each other in a network based on time slots.<br />EDGE standard has the ability to retransmit a packet that has not been decoded properly with a more robust coding scheme. For GPRS, re-segmentation is not possible. Once packets have been sent, they must be retransmitted using the original coding scheme.<br />8/9/2010<br />25<br />
  26. 26. Summary of EDGE<br />8/9/2010<br />26<br />
  27. 27. Comparison between GPRS & EDGE<br />8/9/2010<br />27<br />
  28. 28. EDGE Classic: The EDGE Classic/ EGPRS is based on the EDGE standard developed by the European Telecommunications Standards Institute (ETSI). It offers speed up to 475 Kbps. It is widely used standard.<br />EDGE Compact: <br />EDGE Compact is spectrum-efficient version of EGPRS, which enables the deployment of EDGE in as narrow as 1-MHz frequency bands, it uses the same modulation scheme as EDGE Classic. <br />It offers 384-Kbps packet data rates but will require only minimal spectral clearing and therefore could work for network operators with limited spectrum allocations. EDGE Compact is limited to the packet-switched mode; it does not concern the circuit-switched mode.<br />8/9/2010<br />28<br />
  29. 29. ECSD (Enhanced Circuit Switched Data) is an enhanced version of HSCSD. <br />ECSD increases the bandwidth of each timeslot to 48Kb and allows the use of eight timeslots, which gives a total transmission speed of 384Kbps.<br />8/9/2010<br />29<br />
  30. 30. Convergence of different standards of EDGE<br />8/9/2010<br />30<br />
  31. 31. No new operator licenses are needed for EDGE. Since this feature reuses the existing GSM spectrum.<br /> <br />Provides the low cost solution to operators who wants to provide 3G like multimedia services on their GSM/GPRS networks within the existing spectrum.<br />Backward compatible; If the network is unable to provide EGPRS resources to the mobile because of a congestion, it can allocate GPRS resources instead, if they are available.<br />EDGE can handle about three times more data subscribers than GPRS; Increases throughput by 3x (8-PSK – 3 bits/symbol vs. GMSK 1 bit/symbol)<br />8/9/2010<br />31<br />
  32. 32. Reduced latency for initial access and round-trip time, enabling better quality of service (QoS) for Push-to-Talk (PTT) and Voice over Internet Protocol (VoIP)<br />Lower price per bit for users since it’s not an expensive technology<br />Although EDGE is a data technology, it also helps boost the number of voice calls that a network can handle simultaneously by sending data up to 150 percent more efficiently than GPRS. <br />With EDGE transmitting more data into the same amount of bandwidth, the voice-coding technology in the GSM voice network can be upgraded to a version that increases voice capacity by 15 to 20 percent.<br />8/9/2010<br />32<br />
  33. 33. Evolved EDGE is an upgrade to EDGE to achieve theoretical speeds of up to 1 Mbps with relatively low cost and ease. Also called EDGE Evolution, it promises real downlink speeds of up to 600kbps.<br />The main driving factor of upgrading the existing EDGE is that many operators would like to upgrade their existing infrastructure rather than invest on new network infrastructure. <br />With a software upgrade and a new device compliant with Evolved EDGE for the user, these data rates can be boosted to speeds approaching 1 Mbps. Many service providers may not invest on a completely new technology like 3G/4G networks which costs more.<br />8/9/2010<br />33<br />
  34. 34. Main Features of EDGE EVOLUTION<br />Latency reduction:<br />8/9/2010<br />34<br />
  35. 35. 2. Dual-antenna terminals: <br />By combining signals from the two antennas, a large proportion of the interference can be cancelled out, significantly improving average bit rates and spectrum efficiency. <br />Dual antenna terminals can also improve service coverage. With two antennas and efficient combination methods, weaker signal transmissions can be captured. Around 3 dB less (roughly 50 per cent) signal power is needed to provide service, enabling lower output power.<br />8/9/2010<br />35<br />
  36. 36. 3. Increased bit-rates and improved efficiency using QAM modulation:<br />Using 16QAM instead of 8-PSK modulation for some of the MCS,improves robustness against interference and, as a result, increases the average bit-rates. <br />With 12 MCSs – three more than with regular EDGE, enabled by higher-order modulations (16QAM and 32QAM in addition to GMSK and 8-PSK), the peak bit rate is boosted to 100 kbps per timeslot, equating to user bit-rates of 1 Mbps.<br />8/9/2010<br />36<br />
  37. 37. QAM<br />QAM is a signal in which two carriers shifted in phase by 90 degrees are modulated and the resultant output consists of both amplitude and phase variations. <br />Since both amplitude and phase variations are present it may also be considered as a mixture of amplitude and phase modulation.<br />The various types of QAM may be used when data-rates beyond those offered by 8-PSK are required by a radio communications system such as EDGE. This is because QAM achieves a greater distance between adjacent points in the I-Q plane by distributing the points more evenly. And in this way the points on the constellation are more distinct and data errors are reduced. <br />8/9/2010<br />37<br />
  38. 38. While it is possible to transmit more bits per symbol, if the energy of the constellation is to remain the same, the points on the constellation must be closer together which makes the transmission more susceptible to noise. This results in a higher bit error rate than for the lower order QAM variants. <br />8/9/2010<br />38<br />
  39. 39. 16QAM:16-level constellation 4 bits/symbol and 32QAM: 32-level constellation 5 bits /symbol<br />8/9/2010<br />39<br />
  40. 40. Conclusion<br />EDGE enables 3G like applications over current GSM networks, EDGE can handle three times as much traffic as standard GPRS increasing the usability of mobile data services, enhancing customer satisfaction and boosting data revenues for telecom operators. <br />EDGE Evolution, currently being standardized in 3GPP, will improve performance and coverage even further, with bit-rates of up to 1 Mbit/s and latency below 100 ms.<br />For GSM operators around the world; this makes the business case for EDGE even stronger than it is today – whether or not they have access to 3G spectrum.<br />8/9/2010<br />40<br />
  41. 41. References<br />Emmanuel Seurre, Patrick Savelli, Pierre-Jean Pietri, EDGE for Mobile Internet, Artech House, 2003<br />Timo halonen, Javier Romero, Juan Melero, GSM,GPRS And EDGE Performance, John Wiley and Sons,2nd edition, 2003<br />Ericsson AB’s white paper, THE EVOLUTION OF EDGE, Feb 2007<br /><br />8/9/2010<br />41<br />
  42. 42. Thank You!<br />8/9/2010<br />42<br />