Frequency spectrum is a limited and valuable resource for wireless communications. A good example can be observed among network operators in Europe for the prices to pay for UMTS-frequency bands. Therefore, the first goal when designing future wireless communication systems (e.g. 4G - fourth generation) has to be the increase in spectral efficiency. The development in digital communications in the past years has enabled efficient modulation and coding techniques for robust and spectral efficient data, speech, audio and video transmission. These are the multi-carrier modulation (e.g. OFDM) and the spread spectrum technique (e.g. DS-CDMA), where OFDM was chosen for broadcast applications (DVB, DAB) as well as for broadband wireless indoor standards (ETSI HIPERLAN-II, IEEE-802.11) and the DS-CDMA was selected in mobile communications (IS-95, third generation mobile radio systems world wide, UMTS/IMT 2000). Since 1993 various combinations of multi-carrier (MC) modulation and the spread spectrum (SS) technique have been introduced and the field of MC-SS communications has become an independent and important research topic with increasing activities. New application fields have been proposed such as high rate cellular mobile, high rate wireless indoor and LMDS. It has been shown that MC-SS offers the high spectral efficiency, robustness and flexibility that is required for the next generation systems. Meanwhile, different alternative hybrid schemes such as OFDM/OFDMA, MC-TDMA, etc. have been deeply analysed and adopted in different international standards (ETSI-BRAN, IEEE-802 & MMAC). Multi-Carrier & Spread-Spectrum: Analysis of Hybrid Air Interfaces draws together all of the above mentioned hybrid schemes therefore providing a greatly needed resource for system engineers, telecommunication designers and researchers in order to enable them to develop, build and deploy several schemes based on MC-transmission for the next generation systems (which will be an integration of broadband multimedia services covering both 4G mobile and fixed wireless systems). * Offers a complete treatment of multi-carrier, spread-spectrum (SS) and time division multiplexing (TDM) techniques * Provides an in-depth insight into hybrid multiple access techniques based on multi-carrier (MC) transmission * Presents numerous hybrid multiple access and air interface architectures including OFDM/CDMA, MC-CDMA, MC-DS-CDMA and MT-CDMA * Covers new techniques such as space-time coding and software radio Telecommunications engineers, hardware & software system designers and researchers as well as students, lecturers and technicians will all find this an invaluable addition to their bookshelf.

Stefan Kaiser Khaled Fazel Radio System Design German Aerospace Center (DLR) Marconi Communications lnstitute of Communications and Navigation D-71522 Backnang, Germany D-82234 Wessling, Germany We are currently observing that frequency spectrum is a limited and valuable resource for wireless mobile communications. A good example can be observed among European network operators for the prices to pay for frequency bands for UMTS/IMT2000. Keeping this in mind, the fIrst goal when designing future wireless communication systems has to be the increase in spectral effIciency by allowing higher flexibility for the system design and deployment. The development in digital communications in the past years has enabled effIcient modulation and coding techniques for robust and spectral effIcient data, speech, audio and video transmission. Here, we should mention two interesting and successful techniques. These are the multi-carrier modulation (e. g. OFDM) and the spread spectrum technique (e. g. DS-CDMA). During the last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has received wide interest. Its fIrst great success was in 1990 as it was selected for the European Digital Audio Broadcasting (DAB) standard. Its further prominent success was in 1995 and 1998 as it was selected as modulation scheme for the European Digital Video Broadcasting (DVB-T) standard and in three broadband wireless indoor standards, namely European ETSI-HIPERLAN/2, American IEEE-802. 11a and Japanese MMAC, respectively.

Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow­ band interference rejection capability, etc. . The basic principle of this combination is straightforward: The spreading is performed as direct SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side have motivated many researchers to investigate the combination of both techniques since 1993. This combination known as multi-carrier spread spectrum (MC-SS) benefits from the advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: The spreading is performed as direct sequence spread spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers are employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users' signals can be performed in the code domain. MC-SS systems can perform the spreading in frequency direction, which allows for simple signal detection strategies. Since 1993, MC-SS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA.

Postmemories of Terror focuses on how young Argentineans remember the traumatic events of the military dictatorship (1976-83). This fascinating work is based on oral histories with sixty-three young people who were too young to be directly victimized or politically active during this period. All were born during or after the terror and possessed an entirely mediated knowledge of it. Susana Kaiser explores how the post-dictatorship generation was reconstructing this past from three main sources: inter-generational dialogue, education and the communication media. These conversations discuss selected and recurrent themes like societal fears and silences, remembering and forgetting, historical explanations and accountability. Together they contribute to our understanding of how communities deal with the legacy of terror.

Postmemories of Terror focuses on how young Argentineans remember the traumatic events of the military dictatorship (1976-83). This fascinating work is based on oral histories with sixty-three young people who were too young to be directly victimized or politically active during this period. All were born during or after the terror and possessed an entirely mediated knowledge of it. Susana Kaiser explores how the post-dictatorship generation was reconstructing this past from three main sources: inter-generational dialogue, education and the communication media. These conversations discuss selected and recurrent themes like societal fears and silences, remembering and forgetting, historical explanations and accountability. Together they contribute to our understanding of how communities deal with the legacy of terror.

Stefan Kaiser Khaled Fazel Radio System Design German Aerospace Center (DLR) Marconi Communications lnstitute of Communications and Navigation D-71522 Backnang, Germany D-82234 Wessling, Germany We are currently observing that frequency spectrum is a limited and valuable resource for wireless mobile communications. A good example can be observed among European network operators for the prices to pay for frequency bands for UMTS/IMT2000. Keeping this in mind, the fIrst goal when designing future wireless communication systems has to be the increase in spectral effIciency by allowing higher flexibility for the system design and deployment. The development in digital communications in the past years has enabled effIcient modulation and coding techniques for robust and spectral effIcient data, speech, audio and video transmission. Here, we should mention two interesting and successful techniques. These are the multi-carrier modulation (e. g. OFDM) and the spread spectrum technique (e. g. DS-CDMA). During the last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has received wide interest. Its fIrst great success was in 1990 as it was selected for the European Digital Audio Broadcasting (DAB) standard. Its further prominent success was in 1995 and 1998 as it was selected as modulation scheme for the European Digital Video Broadcasting (DVB-T) standard and in three broadband wireless indoor standards, namely European ETSI-HIPERLAN/2, American IEEE-802. 11a and Japanese MMAC, respectively.

Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow­ band interference rejection capability, etc. . The basic principle of this combination is straightforward: The spreading is performed as direct SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow­ band interference rejection capability, etc. . The basic principle of this combination is straightforward: The spreading is performed as direct SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

Stefan Kaiser Khaled Fazel Radio System Design German Aerospace Center (DLR) Marconi Communications lnstitute of Communications and Navigation D-71522 Backnang, Germany D-82234 Wessling, Germany We are currently observing that frequency spectrum is a limited and valuable resource for wireless mobile communications. A good example can be observed among European network operators for the prices to pay for frequency bands for UMTS/IMT2000. Keeping this in mind, the fIrst goal when designing future wireless communication systems has to be the increase in spectral effIciency by allowing higher flexibility for the system design and deployment. The development in digital communications in the past years has enabled effIcient modulation and coding techniques for robust and spectral effIcient data, speech, audio and video transmission. Here, we should mention two interesting and successful techniques. These are the multi-carrier modulation (e. g. OFDM) and the spread spectrum technique (e. g. DS-CDMA). During the last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has received wide interest. Its fIrst great success was in 1990 as it was selected for the European Digital Audio Broadcasting (DAB) standard. Its further prominent success was in 1995 and 1998 as it was selected as modulation scheme for the European Digital Video Broadcasting (DVB-T) standard and in three broadband wireless indoor standards, namely European ETSI-HIPERLAN/2, American IEEE-802. 11a and Japanese MMAC, respectively.

The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side have motivated many researchers to investigate the combination of both techniques since 1993. This combination known as multi-carrier spread spectrum (MC-SS) benefits from the advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: The spreading is performed as direct sequence spread spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers are employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users' signals can be performed in the code domain. MC-SS systems can perform the spreading in frequency direction, which allows for simple signal detection strategies. Since 1993, MC-SS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA.

Frequency spectrum is a limited and valuable resource for wireless communications. A good example can be observed among network operators in Europe for the prices to pay for UMTS-frequency bands. Therefore, the first goal when designing future wireless communication systems (e.g. 4G - fourth generation) has to be the increase in spectral efficiency. The development in digital communications in the past years has enabled efficient modulation and coding techniques for robust and spectral efficient data, speech, audio and video transmission. These are the multi-carrier modulation (e.g. OFDM) and the spread spectrum technique (e.g. DS-CDMA), where OFDM was chosen for broadcast applications (DVB, DAB) as well as for broadband wireless indoor standards (ETSI HIPERLAN-II, IEEE-802.11) and the DS-CDMA was selected in mobile communications (IS-95, third generation mobile radio systems world wide, UMTS/IMT 2000). Since 1993 various combinations of multi-carrier (MC) modulation and the spread spectrum (SS) technique have been introduced and the field of MC-SS communications has become an independent and important research topic with increasing activities. New application fields have been proposed such as high rate cellular mobile, high rate wireless indoor and LMDS. It has been shown that MC-SS offers the high spectral efficiency, robustness and flexibility that is required for the next generation systems. Meanwhile, different alternative hybrid schemes such as OFDM/OFDMA, MC-TDMA, etc. have been deeply analysed and adopted in different international standards (ETSI-BRAN, IEEE-802 & MMAC). Multi-Carrier & Spread-Spectrum: Analysis of Hybrid Air Interfaces draws together all of the above mentioned hybrid schemes therefore providing a greatly needed resource for system engineers, telecommunication designers and researchers in order to enable them to develop, build and deploy several schemes based on MC-transmission for the next generation systems (which will be an integration of broadband multimedia services covering both 4G mobile and fixed wireless systems). * Offers a complete treatment of multi-carrier, spread-spectrum (SS) and time division multiplexing (TDM) techniques * Provides an in-depth insight into hybrid multiple access techniques based on multi-carrier (MC) transmission * Presents numerous hybrid multiple access and air interface architectures including OFDM/CDMA, MC-CDMA, MC-DS-CDMA and MT-CDMA * Covers new techniques such as space-time coding and software radio Telecommunications engineers, hardware & software system designers and researchers as well as students, lecturers and technicians will all find this an invaluable addition to their bookshelf.

Stefan Kaiser Khaled Fazel Radio System Design German Aerospace Center (DLR) Marconi Communications lnstitute of Communications and Navigation D-71522 Backnang, Germany D-82234 Wessling, Germany We are currently observing that frequency spectrum is a limited and valuable resource for wireless mobile communications. A good example can be observed among European network operators for the prices to pay for frequency bands for UMTS/IMT2000. Keeping this in mind, the fIrst goal when designing future wireless communication systems has to be the increase in spectral effIciency by allowing higher flexibility for the system design and deployment. The development in digital communications in the past years has enabled effIcient modulation and coding techniques for robust and spectral effIcient data, speech, audio and video transmission. Here, we should mention two interesting and successful techniques. These are the multi-carrier modulation (e. g. OFDM) and the spread spectrum technique (e. g. DS-CDMA). During the last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has received wide interest. Its fIrst great success was in 1990 as it was selected for the European Digital Audio Broadcasting (DAB) standard. Its further prominent success was in 1995 and 1998 as it was selected as modulation scheme for the European Digital Video Broadcasting (DVB-T) standard and in three broadband wireless indoor standards, namely European ETSI-HIPERLAN/2, American IEEE-802. 11a and Japanese MMAC, respectively.

Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow­ band interference rejection capability, etc. . The basic principle of this combination is straightforward: The spreading is performed as direct SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side have motivated many researchers to investigate the combination of both techniques since 1993. This combination known as multi-carrier spread spectrum (MC-SS) benefits from the advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: The spreading is performed as direct sequence spread spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers are employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users' signals can be performed in the code domain. MC-SS systems can perform the spreading in frequency direction, which allows for simple signal detection strategies. Since 1993, MC-SS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA.

Postmemories of Terror focuses on how young Argentineans remember the traumatic events of the military dictatorship (1976-83). This fascinating work is based on oral histories with sixty-three young people who were too young to be directly victimized or politically active during this period. All were born during or after the terror and possessed an entirely mediated knowledge of it. Susana Kaiser explores how the post-dictatorship generation was reconstructing this past from three main sources: inter-generational dialogue, education and the communication media. These conversations discuss selected and recurrent themes like societal fears and silences, remembering and forgetting, historical explanations and accountability. Together they contribute to our understanding of how communities deal with the legacy of terror.

Postmemories of Terror focuses on how young Argentineans remember the traumatic events of the military dictatorship (1976-83). This fascinating work is based on oral histories with sixty-three young people who were too young to be directly victimized or politically active during this period. All were born during or after the terror and possessed an entirely mediated knowledge of it. Susana Kaiser explores how the post-dictatorship generation was reconstructing this past from three main sources: inter-generational dialogue, education and the communication media. These conversations discuss selected and recurrent themes like societal fears and silences, remembering and forgetting, historical explanations and accountability. Together they contribute to our understanding of how communities deal with the legacy of terror.

Stefan Kaiser Khaled Fazel Radio System Design German Aerospace Center (DLR) Marconi Communications lnstitute of Communications and Navigation D-71522 Backnang, Germany D-82234 Wessling, Germany We are currently observing that frequency spectrum is a limited and valuable resource for wireless mobile communications. A good example can be observed among European network operators for the prices to pay for frequency bands for UMTS/IMT2000. Keeping this in mind, the fIrst goal when designing future wireless communication systems has to be the increase in spectral effIciency by allowing higher flexibility for the system design and deployment. The development in digital communications in the past years has enabled effIcient modulation and coding techniques for robust and spectral effIcient data, speech, audio and video transmission. Here, we should mention two interesting and successful techniques. These are the multi-carrier modulation (e. g. OFDM) and the spread spectrum technique (e. g. DS-CDMA). During the last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has received wide interest. Its fIrst great success was in 1990 as it was selected for the European Digital Audio Broadcasting (DAB) standard. Its further prominent success was in 1995 and 1998 as it was selected as modulation scheme for the European Digital Video Broadcasting (DVB-T) standard and in three broadband wireless indoor standards, namely European ETSI-HIPERLAN/2, American IEEE-802. 11a and Japanese MMAC, respectively.

Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow­ band interference rejection capability, etc. . The basic principle of this combination is straightforward: The spreading is performed as direct SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow­ band interference rejection capability, etc. . The basic principle of this combination is straightforward: The spreading is performed as direct SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

Stefan Kaiser Khaled Fazel Radio System Design German Aerospace Center (DLR) Marconi Communications lnstitute of Communications and Navigation D-71522 Backnang, Germany D-82234 Wessling, Germany We are currently observing that frequency spectrum is a limited and valuable resource for wireless mobile communications. A good example can be observed among European network operators for the prices to pay for frequency bands for UMTS/IMT2000. Keeping this in mind, the fIrst goal when designing future wireless communication systems has to be the increase in spectral effIciency by allowing higher flexibility for the system design and deployment. The development in digital communications in the past years has enabled effIcient modulation and coding techniques for robust and spectral effIcient data, speech, audio and video transmission. Here, we should mention two interesting and successful techniques. These are the multi-carrier modulation (e. g. OFDM) and the spread spectrum technique (e. g. DS-CDMA). During the last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has received wide interest. Its fIrst great success was in 1990 as it was selected for the European Digital Audio Broadcasting (DAB) standard. Its further prominent success was in 1995 and 1998 as it was selected as modulation scheme for the European Digital Video Broadcasting (DVB-T) standard and in three broadband wireless indoor standards, namely European ETSI-HIPERLAN/2, American IEEE-802. 11a and Japanese MMAC, respectively.

The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side have motivated many researchers to investigate the combination of both techniques since 1993. This combination known as multi-carrier spread spectrum (MC-SS) benefits from the advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: The spreading is performed as direct sequence spread spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers are employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users' signals can be performed in the code domain. MC-SS systems can perform the spreading in frequency direction, which allows for simple signal detection strategies. Since 1993, MC-SS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA.