Carbon Nanotube Antennas for Wireless Communications

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Wireless System Evolution
Cellular:
2G – GPRS – 56-114 kbps
2.5G - EDGE – up to 400 kbps (Evolved EDGE – 1 Mbps)
3G:
HSPA – 7.2 Mbps (AT&T completed 2009)
HSPA+ 21/42 Mbps
LTE/WiMAX/IMT-Advanced – 100 Mbps and higher
LTE: 50 Mbps UL, 100 Mbps DL (deployment in 2012 by AT&T)


WLAN:
802.11n:
>100 Mbps in MAC
>3 bits/sec/Hz
802.11ac (< 6GHz) and 802.11ad (60 GHZ)
>500 Mbps page link throughput
>1 Gbps multiuser access point throughput
>7.5 bits/sec/Hz
(Network throughput is not addressed)



Smart Antennas (keeping within standards):
Range increase
Interference suppression
Capacity increase
Data rate increase using multiple transmit/receive antennas (MIMO)

Radio resource management techniques
Dynamic channel/packet assignment
Adaptive modulation/coding/platform (software defined radio)
Cognitive radio (wideband sensing)

Smart Antennas


Smart antenna is a multibeam or adaptive antenna array that tracks the wireless environment to significantly improve the performance of wireless systems.
Switched Multibeam versus Adaptive Array Antenna: Simple beam tracking, but limited interference suppression and diversity gain, particularly in multipath environments
Adaptive arrays are generally needed for devices and when used for MIMO

Issues

Large arrays at access point/base station/terminal:
Diversity (for MIMO) in small size
700 MHz
Low cost/power signal processing
802.11n: up to 4 on card/computer, but only 1 or 2 at handset
Multiplatform (MIMO) terminals, and the need for multi-band/conformal/embedded antennas, increase the problem
Cognitive radio – cross-layer with
MIMO
Wide bandwidth