Lower energy consumption thanks to high data rates
It may seem against the intuition to reach a low power device by using high-frequency, high-throughput wireless technologies. But, one should consider the fact that the suitability of a design for mobile applications is determined by the energy eciency and not just the instantaneous power consumption. On the rst look, it may seem that a typical high data rate 60 GHz wireless design consumes more power than other wireless technologies over higher distances. But this conclusion is misleading due to the fact that the total power consumption may be reduced by using a higher speed solution because of its ability to operate at a much lower duty cycle than slower radio technologies. Considering this fact, the power eciency is determined by the energy required per bit transmitted. Then, in this case, the faster the radio technology, the lower the actual duty cycle and the lower the amount of energy necessary to transfer each bit of data. Furthermore, the overall power drain is reduced by using the host processor and storage for a shorter period of time . In addition, a high throughput system decreases the time required to complete a transaction and enables the user to quickly accomplish the data transfer. Therefore, using a high throughput communication at 60 GHz is helping to achieve an efficient energy consumer system. Even without considering duty cycle, higher bandwidths and higher data rates lead to better efficiencies. In fact it can be seen from Figure 1.6, that applying more bandwidth per communication link is a significant contributor for improved energy efficiency measured in Bits-per-Joule .
Localization as a support for green radio
It has been mentioned that in the eld of high data rate wireless communications, utilization of spatial resources can play a key role to perform either beamforming or multi-hops.
Beamforming allows focusing the transmitted signal toward the receiver only, thereby decreasing the wasted amount of energy, whereas multi-hop techniques enables smart routing in dynamic networks. The objective way to address the spatial resources is to be able to perform localization in a way to make it as familiar and seamless for the end user as communication.
Thus, as shown in Figure 1.7, proposing an ecient localization method which is adapted to high data rate millimeter-wave communication systems (particularly at 60 GHz), is the vision that this research deals with, in order to ensure green radio communication in the dierent contexts involving indoor mobility or, more recently in the lab, body area networks (BAN).
Since the release of 60 GHz unlicensed bandwidth by the FCC and worldwide eorts to provide and develop standards and specications in order to use this bandwidth for various applications, progress has been made concerning the design and realization of integrated 60 GHz circuits and radio systems. Progress in the areas of antennas design and integration, circuit components shuch as power ampliers (PAs), low noise ampliers (LNAs), voltage controlled oscillators (VCOs), mixers and analog to digital converters (ADCs), millimeter-wave channel characterization and beamforming techniques, makes the use of this bandwidth possible.
Integrated circuit technology and RF 60 GHz components
A demand for high-speed wireless connections and recent progress in silicon-based technologies have driven the development of wireless local area networks (WLANs) standards operating at 60 GHz such as WiGig [14, 36]. Such applications require a low-cost and low-power implementation, which leads to implement system-on-chip for the transceivers and use of advanced CMOS nodes. The choice of integrated circuit (IC) technology depends on:
Implementation aspects: Issues such as power consumption, eciency, dynamic range, linearity requirements are among implementation aspects.
System requirements: Issues such as transmission data rate, modulation scheme, cost and size, transmit power, bandwidth are related to system requirements.
At mm-wave, there are three competing IC technologies:
Gallium Arsenide (GaAs) and Indium Phosphide (InP) technology: GaAs technology oers low noise, fast and high gain implementation but suers from poor integration and expensive implementation.
Silicon Germanium (SiGe) technology such as Heterojunction Bipolar Transistor (HBT) and Bipolar junction transistor and CMOS (BiCMOS): SiGe technology allows low noise, fast and high gain implementation and is a cheaper alternative to the GaAs.
Silicon technology such as CMOS and BiCMOS: CMOS technology performance is not remarkable considering gain and noise and linearity but it provides cheaper product with a high degree of integration . None of these technologies can meet all the implementation challenges and system requirements mentioned above at the same time. However, it should be considered that the size and cost are the key factors regarding mass deployment and market exploitation.
Considering this point of view, CMOS technology is the leading candidate among the others. Recent progress make it possible to obtain thinner CMOS technology such as 28 nm compare to 130 nm in past years [36, 37].
Modulation schemes and MAC protocols
For 60 GHz radio, the choice of modulation scheme relies on:
• the propagation channel.
• the use of high gain antenna/antenna array.
• the limitations imposed by the RF technology [39-46].
It should be noticed that, although simple modulation schemes such as single carrier (SC) can be used to meet some hardware constraints, they exhibit significantly less spectral efficiency. Hence, to find a robust and permanent solution, these simpler modulation techniques are not the best choice. For frequency selective channels with high multi-path effects, an OFDM is a better choice since it can mitigate the multi-path effects by providing flat fading smaller bandwidths. It is done by dividing the high-rate stream into a set of parallel lower rate sub-streams. Furthermore, using OFDM decreases the complexity of the system for multi-giga-bits systems by simplifying the equalization process. OFDM is also well suited at 60 GHz regarding its ability to decrease ISI (Inter Symbol Interference) effects. But it is sensible to phase noise from inter subcarrier interference (ICI) and requires large PAPRs.
Table of contents :
1 Context and objectives
1.2 New applications demanding high data rate communications
1.2.1 Wireless networking and instant wireless synchronization
1.2.2 Wireless display, distribution of HDTV, high quality audio and wireless docking
1.2.3 Intelligent transportation systems
1.2.4 Access and future 5G
1.3 High Data rate communication: millimeter-wave solutions (60 GHz)
1.3.1 Benets of millimeter-wave frequencies for Gb/s communication
1.3.2 Why 60 GHz?
18.104.22.168 Regulatory environment
22.214.171.124 60 GHz implications
1.4 Energy aspects
1.4.1 Lower energy consumption thanks to high data rates
1.4.2 Lower energy consumption thanks to spatial capabilities
1.5 The objective: a better utilization of spatial resources
1.5.1 Localization as a support for green radio
1.5.2 Other applications of indoor localization
2 State of the art of 60 GHz systems and indoor positioning methods
2.2 60 GHz communication systems
2.2.1 Channel issues
126.96.36.199 Propagation characteristics
188.8.131.52 Material impact
2.2.2 Technological aspects
184.108.40.206 Integrated circuit technology and RF 60 GHz components
2.2.3 Modulation schemes and MAC protocols
220.127.116.11 WirelessHD standards
18.104.22.168 IEEE 802.15.3c-2009 standard
22.214.171.124 ECMA 387
126.96.36.199 WiGig and IEEE 802.11ad
2.3 Indoor positioning methods
2.3.1 Angle related measurements
188.8.131.52 Method utilizing receiver antenna’s amplitude response
184.108.40.206 Method utilizing receiver antenna’s phase response
2.3.2 Distance related measurements
220.127.116.11 Received Signal Strength (RSS) measurements
18.104.22.168 Time Of Arrival (TOA) measurements
22.214.171.124 Time Dierence of Arrival (TDOA) measurements
3 New TDOA approach using communication signals
3.2 TDOA metric
3.2.1 Conventional TDOA method
3.2.2 New TDOA method
3.2.3 Mathematical analysis and the direct problem
3.2.4 Inverse problem
3.3 TDOA extraction using IEEE 802.11ad standard
3.3.1 Simulation setup
126.96.36.199 Geometry of acquisition
188.8.131.52 SystemVue simulation
3.3.2 TDOA estimation using EVM of received signal
184.108.40.206 Simulation results
3.3.3 TDOA estimation using equivalent channel response (ECR)
220.127.116.11 Simulations results
18.104.22.168 TDOA estimation
3.3.4 Multi-band approach
3.4 Limitations and validity domain
3.4.1 Channel consideration
22.214.171.124 Simple multi-path inuence on 60 GHz TDOA estimation using EVM
126.96.36.199 IEEE channel inuence on 60 GHz TDOA estimation using ECR
3.4.2 Quality of communication
4 Measurements and experimental results
4.2 Measurements using VNA
4.2.1 Experimental setup and test conditions
4.3 Measurements using Vubiq and VSA
4.3.1 Experimental setups
188.8.131.52 Arbitrary waveform generator (AWG)
184.108.40.206 60 GHz waveguide module development system (V60WGD02)
220.127.116.11 SystemVue interface
4.3.2 Measurements results
18.104.22.168 Free space measurements
22.214.171.124 Guided mono-band measurements
126.96.36.199 Guided multi-band measurements
4.4 Measurements using Highrate transceiver
4.4.1 Experimental setup and test condition
4.5 Multi-band measurements with base-band signals
Conclusion and perspectives
Appendix A: 60 GHz Vubiq Modules
Appendix B: Highrate Transceiver
Appendix C: List of publications