Wireless LANs and mobile networking: standards and future directions

Abstract

The emerging widespread use of wireless LAN systems together with the users' desire for such systems to interoperate has created a requirement for standards. Many standards bodies are currently defining standards for wireless systems that relate to different layers of the networklng protocol stack. Of these, two influential physical and data link layer standard3, IEEE 802.11 and the European HIPERLAN, are described. The article then considers the network layer by discussing extensions that are bcing made to the widely used Internet Protocol (IP) to deal with mobility (wired or wireless). The final standards that are discussed relate to wireless link management. The article concludes by speculating on future directions for wireless LAN systcms. GHz ISM band.The discussion that follows treats several types or emerging standards which impact wireless LAN systems. We begin with a description of two influential physical-and data-link-layer standards, IEEE 802.11 and HIPERLAN. Following this, we briefly examine some developments concerning the U.S. personal communication services (PCS) bands, future spectrum allocations, and wireless asynchronous transfer mode (ATM) systems. After describing these physical-and link-layer developments, we focus o n the network layer. We discuss the extensions being made to the widely used Internet Protocol (IP) to deal with mobility (wired or wireless). Finally, we describe some emerging standards for wireless link management in which interfaccs are specified to provide wireless link information to protocol stacks and applications on the mobile client. In the conclusion, we speculate on futurc directions of wireless LAN systems. IEEE 802.11 WIRELESS LAN STANDARDT he IEEE 802.11 committee has been working on the establishment of a standard for wireless LANs. Having begun its work in 1990, the 802.11 committee is nearing completion of the standard, which is expected to be finalized in mid-1996. Much of the standard appears to have reached final form at the current time (early 1996), so we can descrlbe the main features of the architecture, the multiple physical layers, arid the common medium access control (MAC) sublayer [l]. ARCHITECTUREWe introduce the general architecture and terminology deIined by the 802.11 cornmillee [l]. As shown in Fig. 1, two primary topologies are supported by the 802.11 standard: one in which the stations access the backbone network1 (distribution system in 802.11 nomenclaturc) via access points (Le., base stations), and one in which a group of stations commnnicate directly with each other in an ad hoc network, independent of any infrastructure or base stations. The first topology is useful for providing wireless covcrage of building or campus areas by deploying multiple access points whose radio coverage areas overlap to provide complete coveragc. The stations associated with a given access point are referred to as its basic service set (BSS) in the 802.11 standard, but more commonly as the members of the acccss point's cell. The second topology, the one for a...

Performance Analysis Methods of Non-directed IR Wireless Channel Preparation of Papers for Short Range Inside the Building

“…If the source S and receiver R are described by (2) and (3) in an indoor environment with no reflectors, if the distance R between transmitter and receiver is large relative to the detector size, so that R  » AR, then the received irradiance is approximately constant over the surface of the detector, and furthermore, all of the signal energy will arrive at the receiver at approximately the same time. Thus, using the models described above, the impulse response for this simple system is approximately a scaled and delayed Dirac delta function: (4) Where, dis the solid angle subtended by the receiver's differenti al area (assuming A R « R )…”

“…The coefficient (n+1)/ensures that integrating R() over the surface of a hemisphere results in the source power P S. The radiation mode of n = 1 corresponds to a traditional Lambertian source. To simplify notation, a point source Tthat emits a unit impulse of optical intensity at time zero is represented by S. (2) Where is its position, is its orientation, and n is its mode number. Linearity allows us to consider only unit-impulse sources and scale the results for other sources.…”

Resource reservation with mobile hosts using fuzzy matrices

“…RSVP, a resource ReSerVation Protocol that sets up resource reservations for real-time traf®c is designed for existing networks [9]. A host requesting a speci®c QoS from the network for particular application data streams uses RSVP.…”

Modeling and prediction of session throughput of constant bit rate streams in wireless data networks

“…Various technologies are utilized in wireless data networks, such as Bluetooth [1] in personal area networks (PAN), IEEE 802.11 [2] and HyperLan [3] in wireless local area networks (WLAN), cellular digital packet data (CDPD) [4] in wireless wide area networks (WWAN). In this paper, we focus on the data service in wireless data networks and wireless voice networks [5] providing integrated voice/data services.…”