Range performance evaluation of IEEE 802.11n devices

Abstract

The IEEE 802.11n standard utilizes multiple-input multiple-output (MIMO) technology in order to improve the throughput as well as the transmission range of the communication link. In this paper, the range performance evaluation of IEEE 802.11n standard compliant devices based on different configuration parameters, such as modulation and coding schemes, antenna numbers, and various available MIMO operational modes, is presented. The range improvement provided by IEEE 802.11n MIMO modes over the single-input single-output (SISO) system configuration is highlighted. The improved range reduces the number of required Wi-Fi devices in an area for a given reliability factor, such as the packet error rate (PER). Conversely, the reliability of a link can be improved for a given transmission range. Availability of such performance benchmark figures under different channel conditions allow the commissioning engineer to optimally design the network before the actual deployment. As a result, the overall installation/maintenance cost can be significantly reduced. The obtained results are applicable to both the traditional star as well as mesh topology networks.Keywords-IEEE 802.11n, WLAN, multiple-input multipleoutput (MIMO), link budget, over the air tests (OTA), space-time block coding (STBC), spatial division multiplexing (SDM), transmitter beamforming (TxBF), Maximal Ratio Combining (MRC), communication range, packet error rate (PER), reliability, performance evaluation I. INTRODUCTIONWireless LAN (WLAN) is increasingly being used in outdoor industrial applications in order to address different kinds of communication requirements. WLAN technologies, such as IEEE 802.11n, provides high data rate communication, along with the advantage of working in the unlicensed spectrum that is nearly universally available. Typically, in outdoor industrial communication scenarios, higher link reliability and longer range plays a much important role than the availability of higher throughput. Although, the IEEE 802.11n standard has mainly been considered as an enabling technology to obtain higher throughput, beyond 200Mbps, and data rates up to 600 Mbps [1], [2]; however, by keeping the data rate fixed, the enhanced PHY-layer in IEEE 802.11n also enables improving the link reliability and range. A key PHY-layer modification in IEEE 802.11n includes support for several MIMO operational modes, which were not present in its predecessor technologies. Moreover, IEEE 802.11n allows channel bonding (40 MHz bandwidth), and employment of advanced coding techniques, such as the low density parity check (LDPC) codes.978-1-4799-7800-7/15/$31.00 ©2015 IEEE

Long range and low powered RFID tags with tunnel diode

“…19). 100 mW [8] 200 m [9] The tunnel diode-based RFID tag can be easily improved. Amplitude modulation and Manchester encoding have already been illustrated by appropriately biasing on and off the tunnel diode; but sophisticated coding techniques ( [10], [11]) can increase the communication distances.…”