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Introduction To WiMAX & Broadband Access Technologies. Lecture-1b Presented By Laiq Akhtar. Understanding the WiMAX Technology. The working of a basic WiMAX system.
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Introduction To WiMAX & Broadband Access Technologies Lecture-1b Presented By Laiq Akhtar
The working of a basic WiMAX system. • A WiMAX base station is connected to public networks using optical fiber, cable, microwave link, or any other high-speed point-to-point(P-P) connectivity, referred as a backhaul. • WiMAX should use point-to-point antennas as a backhaul to connect aggregate subscriber sites to each other and tobase stations across long distances.
The working of a basic WiMAX system. • A base station serves subscriber stations (also called customer premise equipment [CPE] for obvious reasons) using non-line-of-sight(NLOS) or line-of-sight (LOS) point-to-multi-point connectivity, and this connection is referred to as the last mile.
The working of a basic WiMAX system. • Ideally, WiMAX should use NLOS point-to-multi-point antennas to connect residential or business subscribers to the base station • A subscriber station typically serves a building (business or residence)using wired or wireless LAN.
WiMAX At PTCL • Typically, a WiMAX system consists of two parts’ a WiMAX base station and a WiMAX receiver (also referred as CPE).
Figure Intro - AN-100U Terminal: • The AN-100U consists of an indoor terminal (IDU) and outdoor transceiver and antenna (ODU)
REDMAX BTS (AN-100UX) System Specifications( PTCL) • System Capability: LOS, Optical LOS, non LOS Cell-based point-to-multipoint • RF Band: 3.4-3.6 GHz • Modulation/Coding Rates: Auto-select modulation: BPSK, QPSK, 16 QAM, 64 QAM • Range: LOS: PTP - Over 28 mi (45 km); PMP - 12 mi (20km) NLOS: 1-2 mi (1.7 - 3.3 km) (QPSK 3/4 @ 70% coverage) 0.5 - 1 mi (0.8 - 1.7 km) (16QAM 3/4 @ 90% coverage)
WiMAX Receiver • A WiMAX receiver, which is also referred as CPE, may have a separate antenna (i.e., receiver electronics and antenna are separate modules) or could be a stand-alone box or a PCMCIA card that sits in a laptop or computer. • Access to a WiMAX base station is similar to accessing a wireless access point (AP) in a Wi-Fi network, but the coverage is MORE.
Flavors of WiMAX • WiMAX can provide two flavors of wireless services, depending on the frequency range of operation. These frequency ranges are • 10 to 66 GHz and • 2 to 11 GHz. • The microwave frequencies below 10 GHz are referred to as centimeter bands. • Above 10 GHz, they are known As millimeter bands Millimeter bands have much wider allocated channel bandwidths to accommodate the larger data capacities that are suitable for high data-rate, LOS backhauling applications.
Flavors of WiMAX • Centimeter bands are best for multi-point, near-line-of-sight, tributary, and last mile distribution. • Line-of-Sight • The original 802.16 standard operates • 10 to 66 GHz frequency band • LOS towers. The LOS access service employs a dish antenna that points straight at the WiMAX tower from a rooftop or pole.
Flavors of WiMAX Non-Line-of-Sight • The 802.16a extension, ratified in January 2003, uses a lower frequency of 2 to 11 GHz, enabling NLOS connections. • This was a major breakthrough • in wireless broadband access because LOS between transmission point and the receiving antenna is not necessary. With 802.16a, more customers can be connected to a single tower, substantially • reducing service costs.
Flavors of WiMAX • The NLOS access service is very similar to Wi-Fi, in which a small antenna on a computer connects to the tower. • Lower-frequency transmissions are not as easily disrupted by physical obstructions as the high-frequency transmissions, and they are better able to diffract, or bend, around obstacles. • Based on this principle, WiMAX uses a lower frequency range of 2 GHz to 11 GHz (similar to Wi-Fi) in this mode. • NLOS-style access will be limited to a radius between 4 to 6 mi (perhaps 25 sq mi or 65 sq km of coverage, which is similar in range to a cell phone zone).
Flavors of WiMAX • The WiMAX family of standards addresses two types of usage models: • a fixed-usage model (IEEE 802.16-2004) and • a portable usage model. • OR mobile, nomadic, and fixed wireless access systems.
Types of WiMAX • The basic feature that differentiates these system is the ground speed . Based on mobility, wireless access • can be divided into four classes: • stationary (0 km/hr), • pedestrian (up • to 10 km/hr), • and vehicular (sub classified as “typical” up to 100 km/hr • and “high speed” up to 500 km/hr).
Types of WiMAX • A mobile wireless access system is one that can address the vehicular class, • whereas the fixed serves the stationary and pedestrian classes. • the nomadic wireless access system, which is referred to as a system that works as a fixed wireless access system but can change its location. , i.e., the office during daytime, and moving to another location, i.e., the residence in the evening.
Types of WiMAX Portable or Mobile • The 802.16a extension, ratified in January 2003, uses a lower frequency of 2 to 11 GHz, • enabling NLOS connections. • The latest 802.16e provides by working on developing a specification to enable mobile 802.16 clients. • These clients will be able to hand off between 802.16 base stations, enabling users to roam between service areas.
Types of WiMAX • two cases of portability: full mobility or limited mobility. • The simplest case of portable service (referred to as Nomadicity ) involves a user transporting an 802.16 modem to a different location. • in this scenario the user re-authenticates and manually reestablishes new IP connections and is afforded broadband service at the visited location.
Types of WiMAX • In the fully mobile scenario, user expectations for connectivity are comparable to facilities available in third-generation (3G) voice/data systems. • Users may move around while engaged in a broadband data access or multimedia streaming session. • Mobile wireless access systems need to be robust against rapid channel variation to support vehicular speeds.
