actors are Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hil Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Future Enhancements and Services Future Enhancements and Services near completion. Therefore, EDGE has the potential to increase the data rate of existing GSM systems by a factor of three. EDGE retains other existing GSM parameters, including a frame length, eight time slots per frame, and a 270.833-kHz symbol rate. The GSM 200- kHz channel spacing is also maintained in EDGE, enabling the use of exist- ing spectrum bands. This fact is likely to encourage deployment of EDGE technology on a global scale. Two additional modulation schemes have been proposed and these are Q-O-QAM and B-O-QAM. These two new modula- tion schemes will both result in symbol rates of 361.111 Kbps, but Q-O- QAM will offer a higher bit rate as it supports 2 bits per symbol. Wherever possible, EDGE adopts the GSM standards SO as to minimize the changes required by manufactures and operators who want to support this new technology. Figure 11-6 shows a comparison of the two systems. This includes maintaining the same frequency plan, meaning that 200 kHz will still separate carriers. In addition, the TDMA structure supported by GSM will remain intact at eight time slots per frame. Also, the relationship between logical and physical channels will remain unchanged. The feasibility study carried out by ETSI on EDGE proposes that it will be able to support both transparent and non-transparent circuit-switched services, in addition to the packet-based GPRS. These three new services will be called ECSD-T Enhanced Circuit-Switched Data-Transparent ECSD-NT Enhanced Circuit-Switched Data-Non-Transparent EGPRS Enhanced GPRS Figure 11-6 UMTS (2 Mbps) Comparing EDGE and GSM. EGPRS GSM Data (14.4 Kbps) GSM Data (9.6 Kbps) Circuit-Switched Packet-Switched Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengin