Motorola

About: Motorola is a company organization based out in Schaumburg, Illinois, United States. It is known for research contribution in the topics: Signal & Communications system. The organization has 27298 authors who have published 38274 publications receiving 968710 citations. The organization is also known as: Motorola, Inc. & Galvin Manufacturing Corporation.

Method and apparatus for authentication in a communication system

Abstract: A method and apparatus for authenticating a roaming subscriber. In a preferred embodiment, a subscriber receives a challenge (305) that is in a format of a local authentication protocol, and determines (310) whether the local authentication protocol is the subscriber's home system authentication protocol. If it is not, the subscriber converts the challenge into a format (e.g., bit length) compatible (325) with its home system authentication protocol, and processes the converted challenge with the subscriber's secret key and authentication algorithm into an authentication response (330). The authentication response is converted (335) to be compatible with the local authentication protocol, and transmitted (340) to a local system communication unit. The challenge and response is then forwarded to the subscriber's home system (345) for similar conversion and processing, and the subscriber's response is compared against a home system generated response (355).

One dimensional lithographic proximity correction using DRC shape functions

Abstract: Integrated circuit designs are continually shrinking in size. Lithographic processes are used to transfer these designs to a semiconductor substrate. These processes typically require that the exposure wavelength of light be shorter than the smallest dimension of the elements within the circuit design. When this is not the case, exposure energy such as light behaves more like a wave than a particle. Additionally, mask manufacturing, photoresist chemical diffusion, and etch effects cause pattern transfer distortions. The result is that circuit elements do not print as designed. To counter this effect the circuit designs themselves can be altered so that the final printed results better matches the initial desired design. The process of altering designs in this way is called Lithographic Proximity Correction (LPC). Square (142), cross (162), octagon (172), and hammerhead (202) serifs are added to integrated circuit designs by shape manipulation functions to perform two dimensional (2-D) LPC.

Wireless communication system incorporating multicast addressing and method for use

Abstract: A wireless communication system (200) comprises a connectionless packet network (201) coupled to a plurality of sites (203-208) that are in wireless communication with a plurality of subscriber units (210-217) logically arranged into a plurality of talk groups having corresponding talk group identifications. In one embodiment, each site maintains mappings (220-225) of at least one multicast address to at least one talk group identification. In another embodiment, individual subscriber units maintain such mappings (320). When a subscriber unit affiliates with a given site and talk group (501, 601), the site identifies a multicast address corresponding to the talk group. Based on the multicast address, the site can participate in traffic targeted for the multicast address and, consequently, for the talk group. In this manner, mobility processing is decentralized, system scalability is improved and call setup delays are minimized.

An introduction to PON technologies [Topics in Optical Communications]

Abstract: Passive optical networks are the most important class of fiber access systems in the world today. This article first reviews the reasons why the PON as a general architecture is so important. We then outline in some depth the technologies used to implement this architecture, including the G-PON and E-PON systems being deployed today, and the advanced PON systems that provide the evolution path to ever higher bandwidths

Subspace-based (semi-) blind channel estimation for block precoded space-time OFDM

Abstract: Space time coding has by now been well documented as an attractive means of achieving high data rate transmissions with diversity and coding gains, provided that the underlying propagation channels can be accounted for. We rely on redundant linear precoding to develop a (semi-)blind channel estimation algorithm for space time (ST) orthogonal frequency division multiplexing (OFDM) transmissions with Alamouti's (see IEEE J. Select. Areas Commun., vol.16, p.1451-58, Oct. 1998) block code applied on each subcarrier. We establish that multichannel identifiability is guaranteed up to one or two scalar ambiguities, regardless of the channel zero locations and the underlying signal constellations, when distinct or identical precoders are employed for even and odd indexed symbol blocks. With known pilots inserted either before or after precoding, we resolve the residual scalar ambiguities and show that distinct precoders require half the number of pilots than identical precoders to achieve the same channel estimation accuracy. Simulation results confirm our theoretical analysis and illustrate that the proposed semi-blind algorithm is capable of tracking slow channel variations and improving the overall system performance relative to competing differential ST alternatives.