GSM Fundamentals PDF

Internal OMA000001 GSM Fundamentals ISSUE 4.0 www.huawei.com HUAWEI TECHNOLOGIES CO., LTD. All rights reserved  Upon completion of this cours...

Internal OMA000001 GSM Fundamentals ISSUE 4.0 www.huawei.com HUAWEI TECHNOLOGIES CO., LTD. All rights reserved  Upon completion of this course, you will be able to:  Grasp basic idea of GSM system such as frequency spectrum, frequency reuse etc.  Grasp the structure of the GSM system and the protocol used.  Grasp certain numbers that refer to BSS  Grasp the 4 kinds of channel combination and understand the idea of multi-frame.  Know some radio techniques  Get the idea of EDGE HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2  References ⚫ BSS Feature Description ⚫ BSS Signaling Analysis Manual ⚫ BSC Technical Manual HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 3  Chapter 1 GSM System Overview Chapter 2 GSM Network Structure Chapter 3 Service Area and Number Planning Chapter 4 Channels on the Wireless Interface Chapter 5 Radio Techniques Chapter 6 GPRS & EDGE Introduction HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 4  GSM system overview ⚫ The GSM system is a frequency- and time-division cellular system, each physical channel is characterized by a carrier frequency and a time slot number ⚫ Cellular systems are designed to operate with groups of low-power radios spread out over the geographical service area. Each group of radios serve MSs presently located near them. The area served by each group of radios is called a CELL ⚫ Uplink and downlink signals for one user are assigned different frequencies, this kind of technique is called Frequency Division Duplex (FDD) ⚫ Data for different users is conveyed in time intervals called slots , several slots make up a frame. This kind of technique is called Time Division Multiple Access (TDMA) HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 5  GSM Development 1989 Standard Protocol for GSM take effect 1991 GSM system began to provide service in Europe(2G) 1992 System was named as Global System for Mobile Communication 1994 Provide services for the whole world 1996 Micro Cell Technique is used in GSM system HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 6  Cell Technique Macro Cell and Micro Cell ⚫ A certain radio coverage area formed by a set of transceivers that connected to a set of antennas is called a CELL. ⚫ Macro Cell  In the beginning , High-Power BTSs are adopted to provide services. The BTS covers a wider area , but its frequency utilization is not efficient. So , it can only provide a few channels for subscribers. ⚫ Micro Cell  Later the Low-Power BTS joins the system for getting a better service area with high capacity. At the same time it adopts the frequency reuse technique to improve the efficiency of the frequency utilization and also the whole capacity of the network. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 7  Multiple Access Technique ⚫ Multiple Access Technique allows many subscribers to use the same communication medium. ⚫ There are three kinds of basic Multiple Access Technique : FDMA , TDMA and CDMA. ⚫ GSM system adopt FDD-TDMA (FDMA and TDMA together). HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 8  FDMA ⚫ FDMA uses different frequency channels to accomplish Frequency communication. ⚫ The whole frequency spectrum available is divided into many individual channels (for transmitting and receiving)，every channel can support the traffic for one subscriber or some control information. Time HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 9  TDMA ⚫ TDMA accomplishes the communication in different Frequency timeslot. ⚫ A carrier is divided into channels based on time. Different signals occupy different timeslots in certain sequence , that is , many signals are transmitted on the same frequency in Time different time. HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 10  CDMA ⚫ CDMA accomplishes the Frequency communication in different code sequences. ⚫ Special coding is adopted before transmission, then different information will lose nothing after being mixed and transmitted together on the same frequency and at the same time. Time HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 11  The Frequency Spectrum GSM 900 Uplink Downlink 890 915 935 960MHz Duplex Separation: 45MHz Channel Bandwidth: 200KHz HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 12  The Frequency Spectrum DCS 1800 Base Station Receive Base Station Transmit 1710 1785 1805 1880MHz Duplex Separation: 95MHz Channel Bandwidth: 200KHz HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 13  The Frequency Spectrum Frequency Frequency Downlink Range (MHz) Uplink Frequency Point Spectrum Frequency Available 450.4~457.6 GSM 450 Fu(n)=450.6+0.2(n-259) 259