802.11b, referred to in full as IEEE 802.11b, is the first widely accepted wireless networking standard. It was developed by the Institute of Electrical and Electronics Engineers LAN/MAN Standards Committee (IEEE 802) and ratified in 1999, the same year as its preceding 802.11 amendment, 802.11a.

It extended throughput to up to 11 Mbps on a 2.4 GHz band.  It specified Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) as its medium access method, and due to the method’s protocol overhead, an application can achieve a maximum throughput of 5.9 Mbps using a transmission control protocol (TCP) and 7.1 Mbps using a user datagram protocol (UDP).

A 2.4 GHz band is used for 802.11b devices, making them susceptible to interference from other products operating in the same band, such as baby monitors, microwave ovens and cordless telephones. It is possible for 802.11 cards to operate at 11 Mbps, but if signal quality becomes an issue, the rate decreases to 5.5 Mbps, then 2 Mbps, then 1 Mbps in a process known as Adaptive Rate Selection.

802.11b makes use of complementary code keying (CCK) as its modulation technique. It is a direct extension of the direct-sequence spread spectrum (DSSS) modulation technique defined in the original 802.11 standard, which enabled a release for 802.11b in the early 2000’s.

This occurred at the same time when its predecessor, 802.11a, was experiencing a lag in shipment due to the difficulty in manufacturing 5 GHz components. 802.11b had a number of other advantages over 802.11a, as well: its signals could penetrate further, it has a greater effective overall range, and it is more cost-effective. This led to 802.11b becoming the more popular and widely-used wireless networking standard among consumers.

A point-to-multipoint configuration is employed for 802.11b. This means that an omni-directional antenna is used for communication between an access point and one or more nomadic or mobile clients that are located in a coverage area around the access point.

An 802.11b network has a typical indoor range of 30 meters at 11 Mbps, and 90 meters at 1 Mbps. All the users on a channel dynamically demand-share the overall bandwidth. The standard may also be used in fixed point-to-point arrangements, usually at lengths of up to 8 kilometers, but with a possible maximum range of 80 to 120 kilometers where line of sight can be established.

This is a preferred method over expensive leased lines or microwave communications equipment that is difficult to install, as legal limitations on effective radiated power must be observed by those who choose to apply such installations.