On 60GHz Wireless Communication Systems

The consumer of the telecommunication services of tomorrow will expectto receive the same services in a wireless fashion as he today receivesfrom a fixed network. These services require reliable high data rate. Thisthesis forms part of the 4:th Generation Wireless (4GW) project in thePersonal Computing and Communication (PCC) program, focusing on the keyfactors that are expected to limit the evolution of future wireless communicationsystems. Using a scenario based approach, this work presents a set of possible"telecom futures". Key technical & economical research issues are derived.One of the important requirements in the design of an air interface isits flexibility. User deployed access points and self-planning capabilitiesare the underlying factors that will make the 4GW infrastructure economicallyviable. Indeed, public and private networks are expected to coexist, bothoffering high bit rate communication and a broad range of services.It is shown in this thesis that an Orthogonal Frequency Division Multiplexing(OFDM) based modulation is a good candidate for broadband wireless systems.This scheme is well suited for transmitting high data rates in frequency-selectiveslow fading channels, and, in the case of a properly dimensioned system,the fading experienced by each subchannel becomes flat.The 60 GHz frequency band has been identified as one of the potentialhigh bit-rate bands with 5 GHz of unlicensed bandwidth with a target bitrateof more than 100 Mbit/s per user in offices, shopping-malls and downtownareas. As part of this work, we aim to understand the fundamental issuesinherent to the use of millimeter wave bands for wireless communica tionsystems. Propagation, interference and shadowing issues are presented.Evaluation of DQPSK-OFDM shows the impact of the 60 GHz channel on a givensystem. In addition, we evaluate system performance using Monolithic MicrowaveIntegrated Circuit (MMIC) components developed at Chalmers and identifythe critical characteristics of microelectronic components for the proposedscheme

Broadband Wireless OFDM Systems

While the readiness of the telecommunication market and the users\u27 need for broadband mobile data are not currently noticeable, a set of presented megatrends and scenarios suggest that broadband mobile data access will develop quickly in the next ten years. Identification of the potential frequency bands offering cheap and trouble-free wireless infrastructure is therefore an important step towards the definition of new air interfaces. This thesis approaches many aspects of broadband wireless Orthogonal Frequency Division Multiplexing (OFDM) systems covering a limited list of topics such as market viewpoints, frequency allocation recommendations, channel models, propagation problems and related technical solutions. The goal is to prepare the grounds for next generation broadband mobile data systems, especially regarding the air interface, and gain a better knowledge of the numerous problems involved in their realization. Among several license-exempt frequency bands, we choose to give emphasis to the 60 GHz frequency band. The 60 GHz frequency band is identified as one of the potential very high bit-rate bands offering several GHz of licensed-exempt bandwidth in offces, shopping-malls and downtown areas. The properties of the radio propagation in this band is however still not completely understood. As part of this work, we aim to understand the fundamental issues inherent to the use of millimeter wave bands for wireless communication systems. Propagation, interference and shadowing issues are presented as major impediments at this frequency. Evaluation of OFDM-based air interfaces shows that many issues need to be addressed before one can build an entire 60 GHz infrastructure. We suggest network design solutions that solve some of the inherent channel problems at the price of a lower flexibility and higher network complexity. It seems however that this is the price to pay in order to guarantee proper coverage with good reliability and link performance. In addition, we evaluate 60 GHz system performance using Monolithic Microwave Integrated Circuit (MMIC) components developed at Chalmers and identify the need to develop further 60 GHz microelectronic components. Some results on research related to joint channel estimation and turbo (de)coding with OFDM are also covered

Broadband Wireless OFDM Systems

While the readiness of the telecommunication market and the users\u27 need for broadband mobile data are not currently noticeable, a set of presented megatrends and scenarios suggest that broadband mobile data access will develop quickly in the next ten years. Identification of the potential frequency bands offering cheap and trouble-free wireless infrastructure is therefore an important step towards the definition of new air interfaces. This thesis approaches many aspects of broadband wireless Orthogonal Frequency Division Multiplexing (OFDM) systems covering a limited list of topics such as market viewpoints, frequency allocation recommendations, channel models, propagation problems and related technical solutions. The goal is to prepare the grounds for next generation broadband mobile data systems, especially regarding the air interface, and gain a better knowledge of the numerous problems involved in their realization. Among several license-exempt frequency bands, we choose to give emphasis to the 60 GHz frequency band. The 60 GHz frequency band is identified as one of the potential very high bit-rate bands offering several GHz of licensed-exempt bandwidth in offces, shopping-malls and downtown areas. The properties of the radio propagation in this band is however still not completely understood. As part of this work, we aim to understand the fundamental issues inherent to the use of millimeter wave bands for wireless communication systems. Propagation, interference and shadowing issues are presented as major impediments at this frequency. Evaluation of OFDM-based air interfaces shows that many issues need to be addressed before one can build an entire 60 GHz infrastructure. We suggest network design solutions that solve some of the inherent channel problems at the price of a lower flexibility and higher network complexity. It seems however that this is the price to pay in order to guarantee proper coverage with good reliability and link performance. In addition, we evaluate 60 GHz system performance using Monolithic Microwave Integrated Circuit (MMIC) components developed at Chalmers and identify the need to develop further 60 GHz microelectronic components. Some results on research related to joint channel estimation and turbo (de)coding with OFDM are also covered

Propagation and Interference Issues in a 60 GHz Mobile Network

In the framework of the 4 th Generation Wireless (4GW) Infrastructure project, the study of new air interfaces is needed to provide a broadband wireless infrastructure to mobile users. The 60 GHz frequency band presents a very large bandwidth that has been allocated to mobile communication. In this paper, propagation and interference issues in different environments are presented and analyzed to identify the air interface limitations for the deployment of 60 GHz networks. Simulations using a ray-tracing tool show the dynamics of the interference in chosen situations. The very short time variation scales underline the need of ad-hoc solutions, directional antennas, fast and intelligent IP handovers, and efficient network design

Impact of Shadow Fading in a Mm-Wave Band Wireless Network

The interest in using higher frequency bands for high data rate wireless communication is increasing. Large unlicensed bandwidths are available specifically around 60 GHz. At this frequency, the propagation characteristics allow small cells and efficient frequency reuse. However, wireless communication at 60 GHz is mainly limited to Line-of-Sight (LOS), due to the high absorption loss of most materials. For indoor applications, e.g. wireless LANs, the shadowing caused by persons walking across the LOS can therefore severely degrade the link performance. In this paper, we show and quantify how the loss in received power and the stronger multi-path fading due to shadowing objects yield impaired path loss margins and increased bit error rate. We show that shadowing causes at least 6 dB power loss for 10% of the time. Also, link-layer simulations with a 1024-carrier DQPSK/OFDM air-interface show an error floor of 2.10 -3 at shadowing densities that correspond to typically crowded places..