Toward a Gigabit Wireless Communications System

International Journal of Communication Networks and Information Security (IJCNIS) Vol. 1, No. 2, August 2009

Toward a Gigabit Wireless Communications System

L. Rakotondrainibe, Y. Kokar, G. Zaharia and G. El Zein

Institute of Electronics and Telecommunications of Rennes, IETR - UMR CNRS 6164,
INSA, 20 Avenue des Buttes de Coesmes, CS 14315, 35043 Rennes cedex, France Lahatra.Rakotondrainibe@insa-rennes.fr

Abstract: This paper presents the design and the realization of a hybrid wireless Gigabit Ethernet indoor communications system operating at 60 GHz. As the 60 GHz radio link operates only in a single-room configuration, an additional Radio over Fiber (RoF) link is used to ensure the communications within all the rooms of a residential environment. The system uses low complexity baseband processing modules. A byte synchronization technique is designed to provide a high value of the preamble detection probability and a very small value of the false detection probability. Conventional RS (255, 239) encoder and decoder are used for channel forward error correction (FEC). The FEC parameters are determined by the trade- off between higher coding gain and hardware complexity. The results of bit error rate measurements at 875 Mbps are presented for various antennas configurations.

Keywords: Wireless communications, 60 GHz system, high bit rate, DBPSK modulation, synchronization, BER.

1. Introduction The massive use of high quality multimedia applications such as high definition video streaming, file transfer and wireless Gigabit Ethernet explains the need of 1 Gbps overall throughput. One of the most promising solutions to achieve a gigabit class wireless link is to use millimeter-waves (MMW) for the carrier frequency. Due to the large propagation and penetration losses, 60 GHz Wireless Personal Area Networks (WPANs) are primarily intended for use in short range and single room environments. In addition to the high data rates that can be achieved in this frequency band, the radio waves propagation at 60 GHz has specific characteristics offering many other benefits such as high security and frequency re- use.
   High frequency and even MMW analog communication circuits, which were traditionally built on more expensive technologies such as bipolar or Gallium Arsenide (GaAs), are progressively implemented on CMOS. Table 1 summarizes some experimental previous works about the realized transceiver operating at 60 GHz [1], [2]. Different architectures have been analyzed in order to develop new MMW communication systems for commercial applications [3]-[7]. The selection of a modulation scheme is a primary consideration for any wireless system design and has a large impact on the system complexity and power consumption as well as issues such as amplifier linearity, and oscillator phase noise. Moreover, to determine the appropriate system design at 60 GHz, wireless channel characteristics must be well understood. This includes path loss, material attenuation, multipath effects, and antennas [3], [4]. Hence, other considerations such as synchronization, coding/error correction and equalization must be taking into consideration for the overall system design.
   Table 1. Summary of experimental 60 GHz radio systems

Wigwam (2005) IBM (2006) NEC (2002) Motorola (2004)
Technologies 0.25 µm
SiGe BiCMOS
0.15 µm
AlGaAs/ InGaAs HJFET 0.13 µm SiGe BiCMOS AsGa Modulation

Keywords
OFDM /QPSK
LNA, PA, Mixer, PLL OFDM/QPSK ASK, MSK LNA, PA,
Mixer, LO

ASK

Mod/demod Filter, LNA, doubler
OOK

LNA, PA, Mixer, Multiplier Intermediate Frequency
Performance

4,5-5,5 GHz

250 Mbps 1 m 9 GHz

630 Mbps,
OFDM-10m 1 Gbps, ASK-1m -

1,25 Gbps 7 m

3,5 Gbps
3 m

This paper proposes a hybrid communication system derived from the simplified IEEE 802.15.3c physical (PHY) layer [8] to ensure near 1 Gbps data rate on the air interface. The first system application in a point-to-point configuration is the high-speed file transfer. The system must operate in indoor, line-of-sight (LOS) domestic environments.
The rest of this paper is organized as follows. Sections 2 and 3 describe respectively the transmitter and the receiver block diagrams. In these sections, the radiofrequency (RF) architecture is first presented. Then, the baseband blocks are described. The byte/frame synchronization method also is discussed. Measurement results and analysis are respectively presented in sections 4 and 5. Section 6 concludes the work.
2. Transmitter design
Figure 1 shows the block diagram of the realized transmitter (Tx) system.

Figure 1. 60 GHz Wireless Gigabit Ethernet transmitter
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International Journal of Communication Networks and Information Security (IJCNIS) Vol. 1, No. 2, August 2009

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