Broadband in Australia.doc.doc

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Broadband in Australia.doc.doc

  1. 1. 26.02.2007 Department of Electronic Engineering La Trobe University ELE 3EMT/EMC Engineering Management Technical Research/ Lifelong learning Research Topics Introduction Most of the topics listed below relate to cellular mobile phones. Some communications topics are also included to expand the scope beyond mobile communications. Many of the topics are quite dated and not all students’ interests lie in the communications field. Consequently, you are encouraged to define your research topic in your own particular area of interest by presenting a proposal to myself for approval. The proposal should consist of a brief description of your topic similar to the descriptions below. If you do select one of the topics listed, you will be asked to examine an up-to-date perspective of the topic, for example, looking at developments in the last 1-2 years. Alternatively, you may want to adapt one of the topics listed in which case you should provide me with an updated topic description. In the next few weeks, you will be provided with an overview of mobile systems and the other topics listed. Mobile Background There are a number of generations of mobile phones. The first generation of cellular mobile phones used analogue modulation for transmission of the speech signals. A number of different analogue systems were used in different parts of the world. Australia chose AMPS (Advanced Mobile Phone System.) The analogue systems all suffered from a number of disadvantages. For example, the number of possible simultaneous users is smaller than with digital systems, and it is easy to eavesdrop on calls in the analogue system. In 1993 a digital mobile phone system was introduced in Australia, the standard chosen was GSM (Global System for Mobile). This is based around a multiplexing method that combines Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA). The analogue system has since been phased out. Not long after the introduction of GSM, another second generation system called CDMA (Code Division Multiple Access) was developed. One of the major advantages of CDMA is claimed to to be increased traffic capacity handling. CDMA systems were operated in Australia by both Telstra and Hutchison; both Hutchison and Telstra are currently driving strong campaigns encouraging existing CDMA users to migrate to their respective 3G products.. The third generation, 3G, standard adopted in Australia and many other countries is the WCDMA, wideband CDMA, and was first launched by Hutchison in 2003. If researching mobile topics you should, where possible, use information concerning GSM and 3G rather than the other standards, as these is the most relevant to Australia at present, although much of the information is closely related for the three systems. You will have a number of different assignments related to your chosen topic. All students will do a library assignment and an oral presentation. ELE3EMT students will also write a report on their topic. More detailed information on the requirements for each will be given later. You will be allocated projects in pairs and you will be encouraged to work together. The library assignment will be a joint submission, whereas the talk and report will be individual submissions, preferably providing differing interpretations of the jointly researched material. Each of the pair, although working together, will give a separate oral presentation and a separate report. 1. Speech coding for GSM mobile phones
  2. 2. 26.02.2007 A simple way of digitising speech is simply to sample the speech signal at a sufficiently high rate and convert the value of each sample into a binary number. This method is used in the POTS where a data rate of 64kbits/sec is used. Within recent years much more efficient ways of encoding speech have been developed which reduce the bit rate required. Speech coding is used in the GSM mobile phone system. Describe the steps in speech coding in the GSM system. Explain why this system was chosen. 2. Error-correcting codes for GSM mobile phones and interleaving Due to the fading characteristics of the mobile radio channel, bit errors will occur relatively frequently. These errors can be detected and corrected if the information to be transmitted is first coded using special error-correcting codes. Describe the error codes used in the GSM system when speech is being transmitted and explain why these were chosen. 3. Frame format GSM uses time division multiple access in which different calls are allocated different time slots in a frame. The time slot allocated to one channel also has a well defined structure with different parts allocated to data and other functions such as synchronisation. Describe the frame format used when speech is being transmitted. Explain why the frame has this design and the implication it has for the maximum radius of a GSM cell. 4. Encryption One of the main shortcomings of the analogue system was the ease with which third parties could eavesdrop on calls. In the GSM system the information to be transmitted is first encrypted so that only the intended receiver can decode the signal. Describe the encryption system used in GSM and explain why this, rather than other methods of encryption, was chosen. 5. GSM Modulation format The digital information is used to modulate a carrier signal. The GSM system uses a modulation scheme called GMSK (Gaussian Minimum Shift Keying) which has a number of features which make it particularly suitable to this application. Describe GMSK and explain the reasons why GMSK rather than other modulation methods were chosen for GSM. 6. Frequency Hopping To improve the performance of a GSM system, frequency hopping can be used. This means that a different frequency is used for each transmitted burst. Describe frequency hopping and explain why it can improve performance. Describe how the telephone determines whether frequency hopping is to be used and what the hopping sequence is. Is frequency hopping used in Australia? 7. Propagation in the Mobile phone system There are a number of important aspects to propagation. One is attenuation due to distance. Often there is no direct line of sight between the mobile user and the cell site. In this case the received signal is the sum of a number of reflected signals which vary in strength and phase. The result is that the signal may fade. Moving receivers are subject to Doppler spread. Describe the factors which affect propagation in a mobile telephone system and how these can be modelled.10 8. User network signalling in the mobile phone system - mobile initiated calls When a user wishes to make a call from a mobile phone, a sequence of signalling is required. This is more complicated than the signalling required in POTS. Describe the sequence of signals, their purpose and on what channels they are carried. 9. Antenna design for cars The antenna design is an important component in the performance of the overall system. The antenna on the car must be small and receive signals adequately no matter where the car is within a cell. Describe the factors in designing a car antenna. 10. User network signalling in the mobile phone system - calls to mobile When a call is received by the mobile switching centre for a mobile phone, a sequence of signalling is required. This is more complicated than the signalling required in POTS. Describe the sequence of signals, their purpose and on what channels they are carried. 11. Biological effects of radiation from mobile phones The introduction of the GSM system in Australia was surrounded by some controversy. Some have argued that the radiation from the handset can damage tissue. Describe the effects of radiation from mobile telephones on tissue, the recent research into this topic and the conclusions. 12. Handover (handoff) As a mobile user moves along they may move from one cell to another, in this case a handover must occur so that the call is not dropped. This involves the system detecting where the user is and having a method of transferring the call from one base station to another. Describe how the need for a handover is detected and how handover is achieved. 13. Fax Transmission in the mobile telephone system
  3. 3. 26.02.2007 Increasingly mobile phones are being used for services such as fax transmission. The fax standards were designed to meet the characteristics of the fixed telephone system rather than the mobile system and this makes fax transmission by mobile phones an interesting technological problem. Describe the two different fax transmission options available and the benefits of each. 14. Cell size and shape Cellular mobile phone systems are based on the idea of cells and frequency reuse. A number of different cell shapes and patterns are possible. The 'conventional' cell shape is hexagonal. As the demand for mobile phones has increased a number different strategies have been used to increase the number of cells: the use of microcells and cell sectorisation. Describe the different shapes and the factors that influence what cell shapes are used in a particular cellular network. 15. The SMS service Short messaging is a popular feature of GSM mobile telephone systems. Describe the technical aspects of the SMS system including information about how the data is carried and the network components involved in the SMS service.17. 16. Authentication of GSM mobile phones To avoid some of the security problems which arose in the analogue system, a sophisticated authentication process is used in the GSM system. Describe authentication including the network components and the signalling involved in authentication. 17. Comparison of Spectral Efficiency of the GSM and CDMA mobile phone systems. An important aspect of a cellular system is the number of calls which can be supported by a given bandwidth. Each generation of mobile phones has resulted in a significant increase in spectral efficiency. Discuss the relative spectral efficiency of GSM and CDMA. You should include a discussion of how the spectrum available in a given cell is used and frequency reuse factors. 18. Design of antennas for base stations A variety of antenna designs are used for base stations, depending on the cell size and whether sectorisation is used. The angle of tilt of the antenna can also be varied. Describe the types of antenna which can be used and their advantages and disadvantages. 19. Biological Effects of radiation from mobile base stations Frequently the building of new cellular base stations results in protests from the local community concerned about the effects of radiation. Describe the level of radiation and how it varies with distance from the base station. Also describe research into the effects of radiation from base stations. 20. Interference of GSM mobile phones with heart pacemakers. Because GSM phones concentrate the transmitted energy in short bursts, they are more likely to cause interference with heart pacemakers. Some experts recommend that GSM mobile phones should not be used near pacemakers. Describe the aspects of heart pacemakers and GSM mobile phones which make interference possible and whether research indicates that interference is a significant problem. 21. Telemedicine using GSM mobile phones Because mobile phones are now readily available and can be transported to wherever required, they are now being used for applications of telemedicine such as the transmission of ECG. Describe how GSM is currently used for telemedicine. 22. International roaming with a GSM mobile phone One of the advantages of GSM mobile phones is that many other countries use the same standard. This means that it is possible to use overseas a mobile phone purchased and registered in Australia. International use requires extra signalling and authentication procedures. Describe clearly these procedures. 23. Wireless access protocol - WAP Increasingly mobile phones are being used as a means of accessing the Internet. Recently a new access protocol called wireless access protocol (WAP) has been standardised. Describe WAP and why it is used. 24. VLSI for GSM Key factors in choice of mobile phone are weight, size and power consumption. This means that VLSI technology is extensively used in mobile phone design. Describe in detail the developments in VLSI technology on which the improvements in mobile handsets are based. 25. Use of optical fibre within the mobile phone network Transmission from mobile unit to the base station is by radio transmission, but transmission between the base station and the mobile switching centre can use any of a number of technologies including optical fibres. Describe how optical fibre can be used in this application. 26. SIM cards The SIM module is an essential component of a mobile telephone. Describe the technical features of the SIM card and how it contributes to mobile telephone security.
  4. 4. 26.02.2007 27. Antenna design for handheld mobile telephones The antenna on a handheld mobile telephone must be both small and effective. Describe the factors in the design of the antenna. 28. High Altitude Platforms Because of the difficulty of finding suitable sites for mobile towers, researchers are considering the possibility of 'high altitude platforms'. These would be 'cell towers' in the sky using airships or similar stationary or almost stationary aircraft. These would be much cheaper than satellites and require much less transmitter power because they would be much closer to earth. Describe the advantages and disadvantages of HAPs and the different technologies which have been proposed. 29. 3G mobile telephone system The GSM system can be considered as a second generation mobile telephone system. The third generation system - 3G was introduced into Australia in 2003. Describe the features of the 3 G system which make it better suited to future applications. Why have the Australian carriers, other than Hutchison been so slow to take up the technology? 30. Multimedia Messaging (MMS) Multimedia messaging is now available in Australia. This is similar to SMS but allows transmission of sound and pictures. This was made possible through the introduction of GPRS – sometimes referred to as 2.5G. Describe the features of MMS and how data is transmitted in MMS. What is the impact of 3G on MMS? 31. Interference of GSM mobile phones with hearing aids Because GSM phones concentrate the transmitted energy in short bursts, they are more likely to cause interference with hearing aids. GSM phones cause severe interference in some types of hearing aids. Describe clearly how the radio transmission from mobile telephones can cause interference in hearing aids which are acoustic devices. 32. Automatic Location Identification It is now possible to calculate the position of a mobile phone user by combining information about signals to/from several cell towers. Research in this area has been encouraged by the US government requirement that future mobile telephones have this facility so that the location of emergency phone calls can be quickly and accurately determined. Describe the different possible ALI techniques and the benefits and disadvantages of each. 33. Multiple input-multiple output channels Until very recently it was believed that the fundamental limit on the rate at which data could be transmitted through a channel was set by Shannon's formula. In the last few years it has been shown that in some cases by using multiple transmit antennae and multiple receive antennae the possible data rate can be greatly increased. Describe in simple terms how a MIMO system operates. 34. International Telephone Calls When I arrived in Australia in 1967 the cost of an international phone call was $2.50/minute - $21.52 in today’s dollars. Today calls rated less than 1c/minute are available. Describe the technology and economic factors which have made this possible. 35. Broadband in Australia “I am not comfortable with the prospect that a company in Canada, Japan or Europe could have 20 times the capacity to handle information compared to an Australian company”. – Deputy Prime Minister John Anderson, 2.3.2005. Investigate – Are these concerns still valid in 2006? Evaluate the various technologies for delivering broadband and their adoption rate in Australia. Describe the use of one of the following technologies in Australia. Compare it to the overseas situation 36. ADSL 37. EDGE 38. DECT 39. Cable Modems 40. ATM 41. Comparison GSM and narrowband CDMA Both of these mobile technologies are prevalent in the Australian network – more so GSM. Compare and evaluate the technologies.
  5. 5. 26.02.2007 GSM was selected as the prime technology. Was this a good decision? 42. Security in the mobile system The original analogue cellular mobile system was notorious for its lack of security. Examine the ways in which security has improved with the evolution of the system to 2G and 3G. Are there still problems with security? What problems has the increased security posed for our security services in tapping phone lines? 43. Managing temporary peak traffic loads The Commonwealth Games are about to commence in Melbourne. How do the cellular operators manage such temporary peak load situations? 44. Bluetooth Describe the Bluetooth technology and examine how it evolved. What part does it play in today’s mobile network? Describe other current Bluetooth applications and its future possibilities. 45. VOIP This technology is rapidly superseding the traditional telephony system – POTS - over the existing copper network. Describe the technology, and the extent to which it has been adopted in Australia. What is the likely future trend? 46. WLAN This technology is increasingly used in today’s communications networks. Describe the technology and how it is applied today in Australia. Repeating, if there is another engineering topic which you would like to research, provide me with your topic proposal as described above. George Alexander 26 February 2007
  6. 6. 26.02.2007 Department of Electronic Engineering La Trobe University ELE 3EMT/EMC Engineering Management Technical Research/ Lifelong learning Preferences for Research Topics - (submit one form per pair - complete all four preferences) NAME STUDENT 1:...................................................................................................... NAME STUDENT 2:...................................................................................................... First Preference (include number and title) .......................................................................................................................................... Second Preference (include number and title) .......................................................................................................................................... Third Preference (include number and title) .......................................................................................................................................... Fourth Preference (include number and title) .......................................................................................................................................... E-mail/contact details .......................................................................................................................................... Student talks are scheduled to take place take place on April 30. Provisional times will be scheduled in the next few weeks. You will be expected to attend all of the talks in your allocated session and will be required to complete a comments sheet for the other students in your group. Signature of student 1....................................................................................................... Signature of student 2....................................................................................................... Please return to George Alexander by Monday 26th March Alternatively, if proposing your own topic, give me your proposal, in person or by email, by Monday 19th March.

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