Alcatel-Lucent

About: Alcatel-Lucent is a based out in Stuttgart, Germany. It is known for research contribution in the topics: Signal & Network packet. The organization has 37003 authors who have published 53332 publications receiving 1430547 citations. The organization is also known as: Alcatel-Lucent S.A. & Alcatel.

Multiple access cellular communication with dynamic slot allocation and reduced co-channel interference

Abstract: An apparatus and method reduces co-channel interference in multiple-access cellular communication systems in which frame time or frequency slots are allocated between uplink and downlink. An omnidirectional antenna or a set of directional antennas are used in each cell base station to communicate with users. The frame slots (710,715,720) in which the antennas communicate uplink and downlink information are arranged in accordance with a predetermined frame organization to reduce mixed co-channel interference (CCI). Mixed CCI occurs when a downlink transmission from one base station antenna in a given cell interferes with uplink reception in another base station antenna in a frequency reuse (FR) cell. A potentially-interfering antenna in a given cell is therefore directed to transmit downlink information in a different portion of the frame than that in which a potentially-interfered-with antenna in the frequency reuse cell receives uplink information. The frame slots may be allocated such that only a portion (720) of the available slots are dynamically allocated in accordance with user demand, while the remaining portions are assigned to either uplink (710) or downlink (715) communication.

In-building modulated backscatter system

Abstract: In accordance with the present invention, a radio communications system is disclosed that can operate in one of several Modes which integrate in-building security, location determination, messaging, and data communications capabilities. The radio communication system includes at least one Interrogator for generating and transmitting a radio signal. One or more Tags of the system receive the radio signal. A Backscatter Modulator modulates the reflection of the radio signal using a subcarrier signal, thereby forming a reflected modulated signal. The Interrogator receives and demodulates the reflected modulated signal. The Interrogator can also transmit a first information signal to one or more tags, specifying which tags should respond using the Backscatter Modulator. In the Interrogation Mode, the Interrogator can determine the identity of the Tags in the reading field, and can exchange data with those Tags that have been identified. In the Location Mode, the radio communications system can instruct some or all Interrogators to determine the location of a Tag or Tags within the building, regardless of whether the Tag or Tags are in radio range of the Interrogation Mode. In the Messaging, or low speed data communications Mode, the radio communications system can instruct some or all Interrogators to transmit a command addressed to a particular Tag or Tags, regardless of whether the Tag or Tags are in the reading field of the Interrogation Mode, questing that Tag or Tags perform some action. Other embodiments of the Messaging Mode allow the Interrogator to transmit data in addition to a command to the Tag or Tags, and also for the Tag or Tags to transmit a signal back to the Interrogator. This radio communications system can be interconnected with other communications capabilities such as electronic mail, voice mail, location, inventory management, and other systems.

System for implementing multiple simultaneous meetings in a virtual reality mixed media meeting room

Abstract: The virtual reality mixed media meeting room functions to provide the user with a visually familiar conference format and conference controls that are intuitive to operate. In particular, the system presents the conference participants with a visual representation of the various communication equipment that is typically present in a conference room and that is available in the virtual reality mixed media conference. The operation of this communication equipment is analogous to that of the physical communication equipment, so the conference participant needs no training to actively and efficiently participate in the virtual reality mixed media conference. The various aspects of the virtual reality conference are presented in a rendering that emulates the physical appearance and presence of the physical participants and communication devices that would be present in a traditional conference room. The user interacts with the virtual reality mixed media meeting room via the graphical user interface in a point and click manner, thereby eliminating the need for the conference participant to be aware of specific controls or keyboard entries required in previous systems to control their participation in the conference. Furthermore, switching among the plurality of concurrently active virtual reality mixed media conferences to participate in one of these conferences is accomplished by a visually familiar mechanism, such as panning or traveling through a hallway that interconnects the various virtual reality mixed media "conference rooms." In addition to being able to move among a plurality of conferences, the conference participants in any selected conference can share applications and jointly participate in the modification of presentations and displays.

Enhanced intergrain tunneling magnetoresistance in half-metallic CrO2 films

Abstract: Low-field tunneling magnetoresistance was observed in films of half-metallic CrO2 that were grown by high-pressure thermal decomposition of CrO3. High-temperature annealing treatments modified the intergrain barriers of the as-grown films through surface decomposition of CrO2 into insulating Cr2O3, which led to a threefold enhancement of the low-field magnetoresistance. This enhancement indicates the potential of this simple method to directly control the interface barrier characteristics that determine the magnetotransport properties.

A bound for the least prime ideal in the Chebotarev Density Theorem

Abstract: as x --, oc. In [7] two versions of the Chebotarev density theorem were proved, one unconditional and the other on the assumption of the Generalized Riemann Hypothesis (GRH), each of which expressed ~Zc(X ) as the sum of the main term ICI IC]_lGt Li(x) and an error term which is an effectively computable function of x, i-~-' and the associated field constants n K = [ K : Q ], h i = [L :Q] and dK,dz, (the absolute values of the discriminants of the two fields). Assuming the truth of the GRH for ~L(s), that paper also proved the existence of an effectively computable constant b (independent of K and L) such that for any conjugacy class C, there exists a prime