EDGE Compact and EDGE Classic Packet Data Performance full report
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EDGE Compact and EDGE Classic Packet Data Performance
Even though cellular radio services have been extremely successful in providing untethered voice communications, wireless data services have captured only a limited market share so far. One obstacle for wireless data services is their limited peak bit rates. Existing wireless data rates, up to several tens of kb/s, may be over one order of magnitude short of what is required to make popular applications user-friendly. To accomplish these necessities we go for EDGE(Enhanced Data Rates for GSM Evolution) employs adaptation between a number of modulation and coding schemes (link adaptation) as a means for providing several hundred kb/s peak rates in a macro-cellular environment while supporting adequate robustness for impaired channels. In this paper we discuss the two phases of EDGE, classic and compact. We start our discussion with the link adaptation and incremental tendency techniques. Secondly we go for discussing EDGE classic and compact systems and their deployment scenarios, followed by downlink performance comparison and some MAC layer enhancement techniques which improve the performance.
The GSM system is the most popular second-generation wireless system today. It employs TDMA technology to support mobile users in different environments. This system, initially standardized and deployed in Europe, is currently deployed worldwide. The TDMA community adopted EDGE for high-speed data services in the third- generation, radio transmission technology proposal to ITU for IMT-2000 (UWC-136). Typically, current GSM service providerâ„¢s employ 3/9 or 4/12 reuse plans and they may not impose a different frequency reuse plan for EDGE, which is thus termed EDGE Classic. However, in North America, initial deployment using 1MHz in each direction is being considered due to limited spectrum and the potential need to re-deploy spectrum currently used for ANSI 136 systems. This implies very aggressive frequency reuse having a minimum of only three 200-kHz frequency carriers. This means allocating one frequency to each of the three sectors per base station and reusing the frequency set everywhere (1/3 reuse) and providing control signaling with extra reuse protection in the time domain, which is named EDGE Compact due to its compact spectrum requirement.
MODULATION AND CODING ADAPTATION
The basic concept of EDGE is to provide higher data rates per radio time slot than is possible with GMSK modulation. This allows the support of existing services with a lower number of time slots. In addition it allows the introduction of new services with up to 59.2 kb/s per timeslot or almost 480 kb/s per carrier in multi- slot operation, hence offering an evolution path for GSM to support multimedia applications.
Radio link formats
Discussions in the ETSI workshops resulted in selection of 8PSK/GMSK to provide higher rates than the GMSK modulation with small envelope fluctuations and to provide backward compatibility to GSM and GPRS. The EDGE concept can be seen as an extension of GPRS for packet service, which is called EGPRS. ETSI has also combined EDGE with circuit switched data modes, and these modes are called ECSD. Efficient link adaptation is a key feature for EDGE and has been jointly developed with EDGE enhanced modulation. With a high degree of compatibility in the bandwidth and symbol rates with GSM, EDGE provides higher rates for users with good signal to interference plus noise ratios (SINR). This is achieved by employing lower channel-coding redundancy and/or 8PSK, which carries 3 bits per symbol (as opposed to 1 bit per symbol achieved by GMSK). Table 1 shows the bit rate provided by different MCS (Modulation and Coding Scheme) modes. An EGPRS capable terminal will have 9 modulations and coding schemes available compared to 4 for GPRS.
Radio link control
Radio link control selects among the MCS options, in response to SINR or equivalent quality measures. Link adaptation explicitly changes MCS modes based on link quality estimates, and is also called mode selection. Hybrid ARQ transmits additional redundancy bits after errors are observed. It is made possible by sending the packets with different puncturing patterns from the same mother code during retransmission. This allows data transmission to begin with low redundancy and increases redundancy only when errors occur, thus adaptively changing the effective date rates. The criterion for selecting a particular data-rate as proposed is defined by S=Rc(1-BLERc) where Rc and BLERc are the data-rate and BLER (Block Error Rate, where a block is the RLC (radio link control) block.) for the transmission mode chosen. Figure 1 shows the throughput as a function of SIR for different modes. It is found that this threshold criterion is generally effective in achieving a high aggregate system throughput, but the QoS (Quality of Service) for individual users can be degraded as system load increases. Furthermore, link adaptation requires the receiver to continuously perform quality measurements and provide timely feedback to the transmitter, so typical operation may be with somewhat higher thresholds.
EDGE Compact and EDGE Classic
GSM systems are usually planned on the basis of 4/12 (4 base stations, 3 sectors each, per cluster) or 3/9 frequency arrangements. The carriers that contain broadcast control channels (BCCH carriers) are required to transmit continuously and without hopping on control time slots to facilitate handoff measurements, control channel acquisition, and so on. These carriers usually are arranged in a 4/12 reuse pattern. Traffic channels can frequency-hop and, on non-BCCH carriers, they can use discontinuous transmission (based on voice-activity detection), and if so, typically are arranged in a 3/9 reuse pattern. These arrangements provide the strong SIR protection typically required for delay-intolerant voice services and non-acknowledged control channels. EDGE Classic is defined to be a system using continuous BCCH carriers that are typically in a 4/12 or 3/9 reuse pattern and which requires at least 2.4 MHz bandwidth in each direction. Additional traffic carriers, if available with higher total bandwidth, can be deployed under a lower reuse factor. Some system operators, particularly those in North American where 3G spectrum has been partially allocated for PCS, have to re-allocate in-service spectrum to deploy EDGE.
In that case, EDGE Compact may be used for initial deployment using as little as 1 MHz in each direction allowing only three 200-KHz frequency carriers. This means allocating one frequency to each of the three sectors per base station, and the frequency set is reused at every base station (1/3 reuse for EDGE Compact mode). While good spectrum efficiency is achieved, the provisioning of common control functionality, such as system broadcast information, paging, packet access and packet grant, cannot be deployed with 1/3 reuse. 4/12 or 3/9 reuse is required for reliable control channels. In order to achieve adequate co-channel reuse protection for the control channels, reuse in the time domain is exploited, which requires frame synchronization of base stations. Figure 2 shows an example with 4 timing groups in addition to 1/3 frequency reuse to obtain 4/12 reuse for the control channels.
EDGE Compact uses discontinuous transmission based on a 52 -multiframe2 (a multi-frame consisting of 52 frames) and designates different time slots and frames for sending control information. In blocks (blocks are non-overlapping and are each comprised of timeslots from the same timeslot number of 4 successive frames) when a sector belonging to one of the time-groups transmits or receives common control signaling (serving time-group), the sectors belonging to other (non-serving time-groups) are idle. This creates an effective reuse of 3/9 or 4/12, which is necessary for control signaling, while allowing 1/3 reuse for the traffic channels. Specifically, slots 1, 3, 5 and 7 are used for timing groups 0, 1, 2 and 3, respectively, to send common control information on frames 0-3, 21-24, 34-37 and 47-50. Frames 12, 25, 38 and 51 are also not allowed for traffic as they are reserved as idle frames or to send timing advance, frequency correction or synchronization information. More frames can be allocated for control signaling as needed. Therefore, up to 32 frames or 8 blocks per 52 multi-frame can be allocated for traffic channels on the designated control slots. This is 2/3 that of a regular slot capacity in which 48 frames in a 52 multi-frame are used for traffic in a given non-BCCH slot. When using 3 time-groups (i.e., effectively 3/9 reuse), one of the 4 time-groups is unused and it is instead used as a traffic channel. Figure 3 shows the control channel BLER distribution for both 3/9- and 4/12-reuse based systems. For about 90% of the cases, the BLER is better than 4% and 15% for 4/12 and 3/9 reuse, respectively, corresponding to the overall average BLER of about 2.4% and 5.2 % (not shown in the figure), respectively. The performance of the 3/9-reuse system may not be reliable enough at the tail end of the distribution. However, since the traffic channel performance is highly correlated with that of the control channel, i.e., a mobile station with poor control channel BLER most likely cannot support reliable traffic performance, the tail end performance may not be very crucial. The control channel performance for EDGE Classic is expected to be similar because the same reuse factor is employed for the control channel.
The minimum spectrum required for Compact deployment is 600 kHz and that for Classic is 2.4 MHz (neglecting guard bands in both cases). Therefore, at 2.4 MHz and above, there exists the option of either Compact or Classic deployment. The choice of system is partly dependent on the performance of the systems. The performance in turn is dependent on the reuse configuration employed in the deployment. For the purposes of this study and to eligible valid comparisons, the reuse configurations are such that control channels are always at 4/12 reuse while traffic channels are at 1/3 reuse whenever possible. The exceptions are the traffic channels of a Classic control (BCCH) carrier, which are at 4/12 reuse. We also consider the same control-channel capacity (one active slot of a carrier) for both cases under all scenarios. Table 2 and the text following describe the scenarios considered:
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TECHNICAL PAPER PRESENTATION ON
ENHANCED DATA FOR GSM EVOLUTION
A Mobile communication technology
N.V.RAVI RAJ KIRAN,
Department of Electronics & Communications
Avanthi Institute of Engineering and Technology,
Todayâ„¢s fast growing world needs fast communication either it may be voice or data. This calls for a new technology which is faster than all existing technologies in mobile communication and hence can replace technologies like GPRS. Enhanced Data for GSM Evolution (EDGE) is such a technology .EDGE is a member of global system for mobile communications (GSM).In short EDGE is a technology which enhances data rate for mobile communications. EDGE not only enhances data rates but also intended for efficient spectrum utilization which it has passed successfully. This paper is intended for explaining how theoretical data rates of 384 kbps are possible with EDGE technique. And how enhanced data for global evolution (EDGE) can play an important role in the evolution toward wideband code division multiple access (WCDMA).And this paper also includes brief details on EDGE and modulation scheme used for EDGE. EDGE can be introduced in two ways: (1) as a packet-switched enhancement for general packet radio service (GPRS), known as enhanced GPRS or EGPRS, and (2) as a circuit-switched data enhancement called enhanced circuit-switched data (ECSD). My paper, however, will only discuss the packet-switched enhancement, EGPRS. Due to the minor differences between GPRS and EGPRS, the impact of EGPRS on the existing GSM/GPRS network is limited to the base station system. The base station is affected by the new transceiver unit capable of handling EDGE modulation as well as new software that enable the new protocol for packets over the radio interface in both the base station and base station controller.The core network does not require any adaptations. Due to this simple upgrade, a network capable of EDGE can be deployed with limited investments and within a short time frame. The goal of EDGE is to boost system capacity, both for real-time and best effort services, and to compete effectively with other third- generation radio access networks such as WCDMA and cdma2000.
EDGE is the next step in the evolution of GSM and IS-136. The objective of the new technology is to increase data transmission rates and file transfers. GPRS/EGPRS will be one of the pacesetters in the overall wireless technology evolution in conjunction with WCDMA. Higher transmission rates for specific radio spectrum efficiency and to facilitate resources enhance cap a c i t y b y new applications and increased enabling more traffic for both circuit- capacity for mobile use .With the introduction of EDGE in GSM phase 2+, existing services such as GPRS and high-speed circuit switched data (HSCSD) are enhanced by offering a and packet-switched services. The goal of EDGE is to boost system capacity, both for real-time and best effort services, and to compete effectively with other third- generation new physical layer. The services radio access networks such as themselves are not modified. EDGE WCDMA and cdma2000. introduced within existing
specifications and descriptions rather than by creating new ones. EGPRS is capable of offering data rates of 384 kbps and, theoretically, of up to 473.6 kbps. A new BETWEEN GPRS AND EGPRS Regarded as a subsystem within the GSM standard, GPRS has introduced packet-switched data into GSM networks. Many new protocols modulation technique and error- and new nodes have been introduced tolerant transmission methods, to make this possible. EDGE is a combined with improved link method to increase the data rates on adaptation mechanisms, make these the radio link for GSM. Basically, EGPRS rates possible. This is the key EDGE only introduces new to increased spectrum efficiency and modulation technique and new enhanced applications, such as channel coding that can be used to wireless Internet access, e-mail and transmit both packet-switched and circuit-switched voice and data system and is therefore much easier to services. EDGE is therefore an add- on to GPRS and cannot work alone. GPRS has a greater impact on the GSM system than EDGE has. By adding the new modulation and coding to GPRS and by making introduce than GPRS (Figure.1) In addition to enhancing the throughput for each data user, EDGE also increases capacity. With EDGE, the same time slot can support more users. This decreases the number of adjustments to the radio link radio resources required to support protocols, EGPRS offers significantly the same traffic, thus freeing up h i g h e r t hroughput and capacity. capacity for more data or voice GPRS and EGPRS have different protocols and different behavior on services. EDGE makes it easier for circuit-switched and packet-switched the base station system side. traffic to coexist while making more efficient use of the same radio resources. Thus in tightly planned networks with limited spectrum, EDGE may also be seen as a capacity booster for the data traffic. However, on the core network side; GPRS and EGPRS share the same packet-handling protocols therefore, behave in the same way. Reuse of the existing GPRS core infrastructure (serving GRPS support node/gateway GPRS support node) emphasizes the fact that EGPRS is only an add-on to the base station
EDGE leverages the knowledge gained through use of the existing GPRS standard to deliver significant technical improvements. Figure 2 compares the basic technical data of GPRS and EDGE. Although GPRS and EDGE share the same symbol rate, the modulation bit rate differs. EDGE can transmit three times as many bits as GPRS during the same period of time. This is the main reason for the higher EDGE bit rates. The differences between the radio and user data rates are the result This 384 kbps data rate corresponds to 48 kbps per time slot, assuming an eight-time slot terminal. EDGE modulation technique The modulation type that is used in GSM is the Gaussian of whether or not the packet headers minimum shift keying (GMSK), are taken into consideration. These which is a kind of phase modulation. This can be visualized in an I/Q diagram that shows the real (I) and different ways of calculating imaginary (Q) components of the throughput often cause misunder- transmitted signal (Figure-3). standing within the industry about actual throughput figures for GPRS and EGPRS. The data rate of 384 kbps is often used in relation to Transmitting a zero bit or one bit is then represented by changing the phase by increments of + or - p. Every symbol that is transmitted represents EDGE. The International Tele- one bit; that is, each shift in the phase communications Union (ITU) has defined 384 kbps as the data rate limit represents one bit. To achieve higher bit rates per time slot than those required for a service to fulfill the available in GSM/GPRS, the International Mobile Tele- modulation method requires change. communications-2 0 0 0 ( I M T -2000) standard in a pedestrian environment. EDGE is specified to reuse the channel structure, channel width, channel coding and the existing mechanisms and functionality of GPRS and HSCSD. The modulation standard selected for EDGE, 8-phase shift keying (8PSK), fulfills all of those requirements. 8PSK modulation has the same qualities in terms of from interpretation of the symbols because it is more difficult for the radio receiver to detect which symbol it not matter. Under poor radio conditions, however, it does. The extra bits will be used to add more error correcting coding, and the correct information can be recovered. generating interference on adjacent Only under very poor radio channels as GMSK. This makes it environments GMSK more possible to integrate EDGE channels into an existing frequency plan and assign new EDGE channels in the same way as standard GSM channels. The 8PSK modulation method is a efficient. Therefore the EDGE coding schemes are a mixture of both GMSK and 8PSK.
For GPRS, four linear method where three different coding schemes, designated consecutive bits are mapped onto one symbol in I/Q plane. The symbol rate, or the number of symbols sent within a certain period of time, remains the same as for GMSK, but each symbol now represents three bits instead of one. The total data rate is therefore increased by a factor of three. The CS1 through CS4, are defined. Each has different amounts of error- correcting coding that is optimized for different radio environments. For EGPRS, nine modulation coding schemes, designated MCS1through MCS9, are introduced. These fulfill the same task as the GPRS coding distances between the different schemes. The lower four EGPRS symbols is shorter using 8PSK modulation than when using GMSK. coding schemes (MSC1 to MSC4) use GMSK, whereas the upper five Shorter distances increase the risk (MSC5 to MSC9) use 8PSKmodulation. Figure 4 shows performance for the GMSK both GPRS and EGPRS coding modulated coding schemes. Re- schemes, along with their maximum throughputs .GPRS user throughput reaches saturation at a maximum of 20 kbps with CS4, whereas the EGPRS bit rate continues to increase as the radio quality increases, until throughput reaches saturation at 59.2 kbps .Both GPRS CS1 to CS4 and EGPRS MCS1 to MCS4use GMSK modulation with slightly different throughput performances. This is due to differences in the header size (and payload size) of the EGPRS packets. This makes it possible to re-segment EGPRS packets. A packet sent with a segmentation is not possible with GPRS.
Another improvement that has been made to the EGPRS standard is the ability to retransmit a packet that has not been decoded properly with a higher coding scheme(less error correction) that is not properly received, can be retransmitted with a lower coding scheme (more error correction) if the new radio environment requires it. This re- more robust coding scheme. For segmenting (retransmitting with G P R S , r e -segmentation not another coding scheme) requires changes in the payload sizes of the radio blocks; this is why EGPRS and possible. Once packets have been sent, they must be retransmitted using the original coding scheme even if the GPRS do not have the same radio environment has changed. This has a significant impact on the throughput, as the algorithm decides the level of confidence with which the link adaptation (LA) must work ADDRESSING WINDOW Before a sequence of coded radio link control packets or radio blocks can be transmitted over the Um (radio) interface, the transmitter must address the packets with an packets. If an erroneously decoded packet must be retransmitted, it may have the same number as a new packet in t h e q ueue. If so, the protocol identification number. This between the terminal and the information is then included in the header of every packet. The packets network stalls, and all the packets belonging to the same low- layer in GPRS are numbered from 1 to 128.After transmission of a sequence capability retransmitted. frame In must EGPRS, be the of packets (e.g., 10packets), the addressing numbers have been transmitter asks the receiver to verify increased to 2048 and the window the correctness of the packets has been increased to 1024 in order received in the form of an to minimize the risk for stalling. acknowledged/unacknowledged This, in turn, minimizes the risk for report. This report informs the retransmitting low- layer capability transmitters which packet or packets frames and prevents decreased were not successfully decoded and must be retransmitted. Sin c e t h e number of packets is limited to 128 and the addressing window is 64, the packet sending process can run out of throughput (Figure 6).
To increase the performance of the higher coding schemes in EGPRS (MCS7 to MCS9) even at low C/I, the addresses after 64 interleaving procedure has been likelihood of receiving two consecutive error free bursts is higher than receiving four consecutive error free bursts. This means that the higher coding schemes for EDGE have a better robustness with regard to frequency hopping. changed with in changing on a per- burst level. Because a radio block is interleaved and transmitted over four bursts for GPRS, each burst may experience a completely different interference environment. If just one of the four bursts is not properly received, the entire radio block will not be properly decoded and will have to be retransmitted. In the case of CS4 for GPRS, hardly any error protection is used at all. With EGPRS, the standard handles the higher coding scheme differently than GPRS to combat this problem. MCS7, MCS8 and MCS9 actually transmit two radio blocks over the four bursts, and the interleaving occurs over two bursts instead of four. This reduces the number of bursts that must be retransmitted should errors occur. The
CAPACITY & PERFORMANCE
EGPRS introduces a new modulation technique, along with improvements to the radio protocol, that allows operators to use existing frequency spectrums (800, 900, 1800 and 1900 MHz) more effectively. The simple improvements of the existing GSM / GPRS protocols make EDGE a cost-effective, easy-to implement add- on. Software upgrades in the base station system enable use of the new protocol; new transceiver units in the base station e nable use of the new modulation technique.
EDGE triples the capacity of GPRS.
This capacity boost improves the performance of existing applications and enables new services such as multimedia services. It also enables each transceiver to carry more voice and/or data traffic. EDGE enables new applications at higher data rates.
The above emphasized technology is now going to emerge as a full pledged technology due to its This will attract new subscribers and inherent advantages. The increase an operatorâ„¢s customer base. implementation of EDGE can over Providing the best and most attractive s h a d o w t he existing mobile services will also increase customer loyalty. HARMONIZATION WITH WCDMA EDGE can be seen as a foundation toward one seamless GSM technologies in near future. Edge is a straightforward upgrade to GSM and is also compatible with other TDMA systems. In tightly planned networks with limited spectrum, EDGE may also be seen as a capacity booster for and WCDMA network with the data traffic. Thus we can aspire combined core network and different access methods that are transparent to major strides in mobile technologies with EDGE which leverages existing the end user. This part of the GSM / GSM systems and complements EDGE evolution focuses on support for the conversational and streaming service classes, because adequate support for interactive and background services already exists. Additionally, WCDMA for further growth.
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Mobile users continue to demand higher data rates. With the continued growth in cellular services, laptop computer use and the Internet, wireless network providers are beginning to pay an increasing amount of attention to packet data networks. Enhanced Global Packet Radio Service (EGPRS) offers a substantial improvement in performance and capacity over existing GPRS services, in return for a relatively minimal additional investment. EGPRS, commonly called EDGE, achieves these enhancements to the GPRS system primarily by implementing changes to the Physical layer and to the Medium Access Control/Radio Link Control (MAC/RLC) layer. The significant improvements are a new modulation technique, additional modulation coding schemes, a combined Link Adaptation and Incremental Redundancy technique, re-segmentation of erroneously received packets, and a larger transmission window size.
EDGE is the next step in the evolution of GSM and IS- 136. The objective of the new technology is to increase data transmission rates and spectrum efficiency and to facilitate new applications and increased capacity for mobile use. With the introduction of EDGE in GSM phase 2+, existing services such as GPRS and high-speed circuit switched data (HSCSD) are enhanced by offering a new physical layer. The services themselves are not modified. EDGE is introduced within existing specifications and descriptions rather than by creating new ones.
This paper focuses on the packet-switched enhancement for GPRS, called EGPRS. GPRS allows data rates of 115 kbps and, theoretically, of up to 160 kbps on the physical layer. EGPRS is capable of offering data rates of 384 kbps and, theoretically, of up to 473.6 kbps. A new modulation technique and error-tolerant transmission methods, combined with improved link adaptation mechanisms, make these EGPRS rates possible. This is the key to increased spectrum efficiency and enhanced applications, such as wireless Internet access, e-mail and file transfers.
GPRS/EGPRS will be one of the pacesetters in the overall wireless technology evolution in conjunction with WCDMA. Higher transmission rates for specific radio resources enhance capacity by enabling more traffic for both circuit- and packet-switched services. As the Third-generation Partnership Project (3GPP) continues standardization toward the GSM/EDGE radio access network (GERAN), GERAN will be able to offer the same services as WCDMA by connecting to the same core network. This is done in parallel with means to increase the spectral efficiency. The goal is to boost system capacity, both for real-time and best-effort services, and to compete effectively with other third-generation radio access networks such as WCDMA and cdma2000.
Technical differences between GPRS and EGPRS
Regarded as a subsystem within the GSM standard, GPRS has introduced packet-switched data into GSM networks. Many new protocols and new nodes have been introduced to make this possible.
EDGE is a method to increase the data rates on the radio link for GSM. Basically, EDGE only introduces a new modulation technique and new channel coding that can be used to transmit both packet-switched and circuit-switched voice and data services. EDGE is therefore an add-on to GPRS and cannot work alone. GPRS has a greater impact on the GSM system than EDGE has. By adding the new modulation and coding to GPRS and by making adjustments to the radio link protocols, EGPRS offers significantly higher throughput and capacity.
GPRS and EGPRS have different protocols and different behavior on the base station system side. However, on the core network side, GPRS and EGPRS share the same packet-handling protocols and, therefore, behave in the same way. Reuse of the existing GPRS core infrastructure (serving GRPS support node/gateway GPRS support node) emphasizes the fact that EGPRS is only an “add-on” to the base station system and is therefore much easier to introduce than GPRS (Figure 1).
In addition to enhancing the throughput for each data user, EDGE also increases capacity. With EDGE, the same time slot can support more users. This decreases the number of radio resources required to support the same traffic, thus freeing up capacity for more data or voice services. EDGE makes it easier for circuit-switched and packet-switched traffic to coexist ,while making more efficient use of the same radio resources. Thus in tightly planned networks with limited spectrum, EDGE may also be seen as a capacity booster for the data traffic.
EDGE leverages the knowledge gained through use of the existing GPRS standard to deliver significant technical improvements.
Figure 2 compares the basic technical data of GPRS and EDGE. Although GPRS and EDGE share the same symbol rate, the modulation bit rate differs. EDGE can transmit three times as many bits as GPRS during the same period of time. This is the main reason for the higher EDGE bit rates.
The differences between the radio and user data rates are the result of whether or not the packet headers are taken into consideration. These different ways of calculating throughput often cause misunderstanding within the industry about actual throughput figures for GPRS and EGPRS.
The data rate of 384 kbps is often used in relation to EDGE. The International Telecommunications Union (ITU) has defined 384 kbps as the data rate limit required for a service to fulfill the International Mobile Telecommunications-2000 (IMT-2000) standard in a pedestrian environment. This 384 kbps data rate corresponds to 48 kbps per time slot, assuming an eight-time slot terminal.
EDGE Modulation Technique
The modulation type that is used in GSM is the Gaussian minimum shift keying (GMSK), which is a kind of phase modulation. This can be visualized in an I/Q diagram that shows the real (I) and imaginary(Q) components of the transmitted signal (Figure 3). Transmitting a zero bit or one bit is then represented by changing the phase by increments of + _ p. Every symbol that is transmitted represents one bit; that is, each shift in the phase represents one bit.
To achieve higher bit rates per time slot than those available in GSM/GPRS, the modulation method requires change. EDGE is specified to reuse
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AIM OF THE PRESENTATION
• To familiarize the audience what EDGE
TECHNOLOGY is all about.
• To explain it’s advantage over other technology.
• FUTURE SCOPE of the existing technology.
• EDGE TECHNOLOGY:
What is Edge?
• Enhance data rate for GSM evolution (EDGE) is a digital mobile phone technology.
• It is generally classified as a 2.75G network technology.
How is EDGE related to mobile phones ?
• EDGE has been introduced into GSM network around the since world since 2003 initially in North American.
• EDGE was adopted by UWCC in January 1998 as the outdoor component of 136HS to provide 384 kb/s data services.
• This was in support of the technology evolution for GSM and TDMA/ 136 systems.
• EDGE is a technology that gives GSM Networks the capacity to handle services for 3G EDGE was developed to enable the transmission of large amounts of data at peak rates of upto 472 kbps.
• Users should experience average speeds of 80 kbps to 130 kbps. EDGE deployment will begin in 2003 with full deployment finishing in 2004.
• EDGE devices are backwards compatible with GPRS and will be able to operate on GPRS networks where EDGE has not yet been deployed.
• Edge (Enhance data rate for GSM evolution) is a radio signaling technology for 3G mobile networks.
• EDGE use for mobile service such as downloading of video and music clips full multimedia messaging high- speed colors internet access and e-mail on the move.
• It can be used for any packet switching application such as an internet connection.
• EDGE circuit switching is a possible for future development.
• It increase data rates up to 384 kbps.
• Introduces a new modulation technique (8PSK) and channel coding.
HOWDOES EDGE WORK ?
• Edge work by improving the signaling interface used to communicate over the radio wave.
• Typically edge enhance thee time the performance of GPRS achieving an data rate 80 to160 kbps per user with mobile terminals.
• EDGE is an improvement to the GPRS air interface that enables higher user bit rates and greater system capacity by enhancing the physical layer.
• The higher bit rates place extra demands on parts of the GPRS network The core GPRS nodes, SGSN and GGSN, are more or less independent of user bit rates and no new hardware is required.
• In the radio network, base station transceivers need to be EDGE-capable, and base station and BSC/PCU software needs to be updated.
• EDGE improves the situation by employing a new modulation method and link quality control. 8-PSK is a high-level linear modulation method that carries three times more information through an extended signal constellation.
Impact ofEDGE on existingGSM/GPRS networks
• Hardware upgrade to the BSS (new transceiver in
• each cell)
• Software upgrade to the BS and BSC
• No change in the core networks
• New terminals
-Terminal which provides 8PSK in the uplink and
• the downlink
-Terminal which provides GMSK in the uplink and 8PSK in the downlink
• In addition to Gaussian minimum- shift keying (GMSK),EDGE uses higher-order PSK/8 phase shift keying (8PSK).
• EDGE produces a 3-bit word for every change in carrier phase.
Coding schemes (modulation coding schemes
• Measurement accuracy
• It is done by measuring bit error rate ,carrier strength etc.
• It has done by quickly to select the right coding scheme.
DATA TRANSMISSON IN EDGE
• The current GSM standard provides data services with user bit rates up to 14.4 kb/s .
• Higher bit rates can be achieved with multislot operation, but since both high-speed circuit-switched data (HSCSD) and General Packet Radio Service (GPRS) .
• EDGE provides high data services with user bit rates up to 59.2 kb/s.
• EDGE modulation technique
• Edge link controlling function
• It uses a combination of 2 functionalities :
FUTURE OF EDGE
• Balanced improved bit rate at all radio conditions
• No hardware, software change to GSM core networks
• Supports download various file types
• Handle four times the traffic of standard GPRS
• Smart & adaptive antennas
• Triples gross data rate by GSM
• Circuit-switched and packet-switched traffic coexist
ADVANTAGE OF EDGE
• Rapid Internet and WAP access
• Service available for EDGE phones without tariff charge
• Avoids creating new system
• EDGE requires base station modifications
• Extra mobile terminal hardware and software required
• Frequently referred to as 2.75G
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15-03-2011, 04:33 PM
This is the main thing about it. EDGE is the next step in the evolution of GSM and IS-136. The objective of the new technology is to increase data transmission rates and file transfers. GPRS/EGPRS will be one of the pacesetters in the overall wireless technology evolution in conjunction with WCDMA. It is the most important in the GSM.