On 60GHz Wireless Communication Systems

Licentiate thesis, 2000

The consumer of the telecommunication services of tomorrow will expect to receive the same services in a wireless fashion as he today receives from a fixed network. These services require reliable high data rate. This thesis forms part of the 4:th Generation Wireless (4GW) project in the Personal Computing and Communication (PCC) program, focusing on the key factors that are expected to limit the evolution of future wireless communication systems. 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 is its flexibility. User deployed access points and self-planning capabilities are the underlying factors that will make the 4GW infrastructure economically viable. Indeed, public and private networks are expected to coexist, both offering 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-selective slow 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 potential high bit-rate bands with 5 GHz of unlicensed bandwidth with a target bitrate of more than 100 Mbit/s per user in offices, shopping-malls and downtown areas. As part of this work, we aim to understand the fundamental issues inherent to the use of millimeter wave bands for wireless communica tion systems. Propagation, interference and shadowing issues are presented. Evaluation of DQPSK-OFDM shows the impact of the 60 GHz channel on a given system. In addition, we evaluate system performance using Monolithic Microwave Integrated Circuit (MMIC) components developed at Chalmers and identify the critical characteristics of microelectronic components for the proposed scheme.