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EMC and Wireless Technologies
Published in Christos Christopoulos, Principles and Techniques of Electromagnetic Compatibility, 2022
WMAN is based on the IEEE 802.16 standard and extends the capabilities of WiFi and links up with WWAN applications. It competes with cables for “last mile” broadband access. WiMAX (Worldwide Interoperability for Microwave Access) is a forum of vendors of equipment based on this family of standards.23 The 802.16–2004 covers the frequency range 2 to 66 GHz with commonly used frequencies in the range 2.45 to 5.825 GHz. A more recent standard, 802.16e, has a narrower frequency range (2 to 11 GHz) and more sophisticated modulation and access techniques based of OFDM for greater flexibility and lower power consumption. Bandwidth is in the range 1 to 28 MHz and peak data rate 134 Mbits/s (for 28 MHz BW), but typically 75 Mbits/s, and 15 Mbits/s for the 802.16e. WiBro is also based on the 802.16e standard and is supported by Korean manufacturers.
Cross-Layer Design in WirelessMAN
Published in Yan Zhang, Hsiao-Hwa Chen, Mobile Wimax, 2007
IEEE 802.16e systems can support time division duplex (TDD) and frequency division duplex (FDD). The frame can be composed of several zones that are divided according to subcarrier allocation methods or multiple-input multiple-output (MIMO) modes. Figure 9.4 shows an example of an IEEE 802.16 TDD frame structure, which is also a model frequently mentioned when constructing wireless broad band (WiBro) systems that support only TDD mode. (WiBro is the Korean wireless broadband service based on Mobile Worldwide Interoperability of Microwave Access [WiMAX] technology and is compatible with the IEEE 802.16e orthogonal frequency division multiple access [OFDMA]/TDD system with a 1024 fast fourier transform [FFT] size.) In the case of an FDD frame structure, the downlink (DL) and uplink (UL) subframes are allocated in a different frequency band without guard time such as the transmit/receive transmission gap (TTG) and receive/transmit transmission gap (RTG).
Contemporary Wireless Technologies
Published in G. S. V. Radha Krishna Rao, G. Radhamani, WiMAX, 2007
G. S. V. Radha Krishna Rao, G. Radhamani
WiBro (wireless broadband) is an Internet technology being developed by the Korean telecom industry (Figure 2.9). In February 2002, the Korean government allocated 100 MHz of electromagnetic spectrum in the 2.3-GHz band, and in late 2004, WiBro Phase 1 was standardized by the TTA (Telecommunications Technology Association) of Korea. WiBro is the newest variety of mobile wireless broadband access. It is based on the same IEEE 802.16 standard as WiMAX but is designed to maintain connectivity on the go, tracking a receiver at speeds of up to 37 mi per hr (60 km/hr). WiMAX is the current standard in the United States, offering wireless Internet connectivity to mobile users at fixed ranges of up to 31 mi (50 km) from the transmitting base. However, it is not designed to be used while the receiver is in motion. WiBro can be thought of as mobile WiMAX, though the technology and its exact specifications will change as it undergoes refinements throughout its preliminary stages. Korean-based fixed-line operators KT, SK Telecom, and Hanaro Telecom were awarded licenses by the South Korean government to provide WiBro commercially. According to Asia Media News Daily, the Korean Times reported a glitch in the initial excitement of WiBro, as published in 2005. Hanaro Telecom gave up its license for WiBro after concerns that the considerable investment required would not see a return, and SK Telecom was also said to be hanging back. Only KT Corp remained enthusiastically committed in the push to make WiBro a reality. Meanwhile, Samsung has shown great interest in providing devices with WiBro capability (Figure 2.9, Figure 2.10, Figure 2.11, and Figure 2.12).
A novel wearable wideband antenna for application in wireless medical communication systems with jeans substrate
Published in The Journal of The Textile Institute, 2021
Farzad Khajeh-Khalili, Yasaman Khosravi
In this paper, a novel wearable wideband antenna with a bandwidth equal to 5.1 GHz is designed. To increase the bandwidth, the proposed five parallel metal plates (PMPs) are used. With this method, the bandwidth is increased by more than 3 GHz. Instead of hard and non-flexible dielectric, the jeans substrate is used in this antenna. The proposed antenna was fabricated to prove the designs and simulations performed. The results of the measurements are well proportional to the simulation results. The final dimensions of the antenna are equal to 60 × 48 × 0.8 mm3 or 0.72 × 0.57 × 0.009 λg3 where λg is the guided wavelength at 2.4 GHz. The proposed antenna operates at frequencies of 0.9–6 GHz for several wireless communications and medical/communication applications such as industrials, scientific, and medical (ISM) bands (902-928/2400-2500/5725-5875 MHz), digital cellular system (DCS) band (1.71–1.85 GHz), personal communication service (PCS) band (1.85–1.99 GHz), universal mobile telecommunications system (UMTS) band (1.92–2.17 GHz), WiBro (wireless broadband) frequencies (2.3–2.39 GHz), WLAN (wireless local area network)+Bluetooth (2.4–2.48 MHz), WiMAX (worldwide interoperability for microwave access) bands (2.5–2.69/3.3–3.5 GHz), HiperLAN2 (high-performance radio LAN2) bands (5.15–5.35/5.47–5.725 GHz), and WLAN (5.15–5.35/5.725–5.825 GHz).
Dual-band elliptical wide-slot antenna with high BDR for portable wireless applications
Published in International Journal of Electronics, 2021
Necessity to integrate several wireless communication standards in a single antenna without much compromise with their performance pose a major challenge to antenna engineers (Josifovska, 2004). Wireless handheld devices including mobile handset, personal digital assets (PDA), laptops are few examples of wireless devices that use several communication standards such as wireless local area network (WLAN) or popularly known as WiFi centred around 2.4/5.2/5.8 GHz, worldwide interoperability for microwave access (WiMAX) at 2.5/3.5/5.5 GHz, wireless broadband (Wibro in Korea), Bluetooth at 2.4 GHz, global positioning system (GPS) at 1.575 GHz and long-term evolution (LTE) at 3.6 GHz (Pontes et al., 2008). The aforementioned wireless devices are highly compact and hence have limited space for the antenna system. Therefore, they require such antennas that are compact and easy to instal along with multiband operability. For addressing the multiband and compactness issues, considerable research for obtaining such antennas which can work for multiple wireless standards simultaneously with low profile has been performed and is still going on.
Implementation of a Regional Spectrum Sensing Based Cognitive Radio System for Digital TV White Space
Published in IETE Technical Review, 2018
Byung Moo Lee, Hyungjoon Song, Jong-Sik Lee
The CR mobile WiMAX system we provide here is a regional-based system, where a centralized DTV spectrum sensor is located in some location and periodically senses the DTV band, from 470 to 698 MHz without stopping. The gathered DTV white space information/channel status is reported to the RMS and the RMS maintains and/or updates the channel information. When a CR mobile WiMAX AP is turned on, it requests channel assignment to the RMS and the RMS assigns two consecutive white space DTV channels (12 MHz) as a round robin fashion for the WiMAX. The WiMAX AP notifies the assigned channels to the MS through the control channel, in our system 2.4 GHz WiFi for simplicity. Then the WiMAX AP starts the service. The mobile WiMAX service in our system is based on Korea Telecom (KT) WiBro which uses the IEEE 802.16 8.75 MHz BW profile. The DTV spectrum sensor, RMS, and WiMAX AP are connected through a wired backbone.