Showing papers by "Qualcomm published in 2003"

User cooperation diversity. Part I. System description

Abstract: Mobile users' data rate and quality of service are limited by the fact that, within the duration of any given call, they experience severe variations in signal attenuation, thereby necessitating the use of some type of diversity. In this two-part paper, we propose a new form of spatial diversity, in which diversity gains are achieved via the cooperation of mobile users. Part I describes the user cooperation strategy, while Part II (see ibid., p.1939-48) focuses on implementation issues and performance analysis. Results show that, even though the interuser channel is noisy, cooperation leads not only to an increase in capacity for both users but also to a more robust system, where users' achievable rates are less susceptible to channel variations.

User cooperation diversity. Part II. Implementation aspects and performance analysis

Abstract: For pt.I see ibid., p.1927-38. This is the second of a two-part paper on a new form of spatial diversity, where diversity gains are achieved through the cooperation of mobile users. Part I described the user cooperation concept and proposed a cooperation strategy for a conventional code-division multiple-access (CDMA) system. Part II investigates the cooperation concept further and considers practical issues related to its implementation. In particular, we investigate the optimal and suboptimal receiver design, and present performance analysis for the conventional CDMA implementation proposed in Part I. We also consider a high-rate CDMA implementation and a cooperation strategy when assumptions about the channel state information at the transmitters are relaxed. We illustrate that, under all scenarios studied, cooperation is beneficial in terms of increasing system throughput and cell coverage, as well as decreasing sensitivity to channel variations.

From theory to practice: an overview of MIMO space-time coded wireless systems

Abstract: This paper presents an overview of progress in the area of multiple input multiple output (MIMO) space-time coded wireless systems. After some background on the research leading to the discovery of the enormous potential of MIMO wireless links, we highlight the different classes of techniques and algorithms proposed which attempt to realize the various benefits of MIMO including spatial multiplexing and space-time coding schemes. These algorithms are often derived and analyzed under ideal independent fading conditions. We present the state of the art in channel modeling and measurements, leading to a better understanding of actual MIMO gains. Finally, the paper addresses current questions regarding the integration of MIMO links in practical wireless systems and standards.

On beamforming with finite rate feedback in multiple-antenna systems

Abstract: We study a multiple-antenna system where the transmitter is equipped with quantized information about instantaneous channel realizations. Assuming that the transmitter uses the quantized information for beamforming, we derive a universal lower bound on the outage probability for any finite set of beamformers. The universal lower bound provides a concise characterization of the gain with each additional bit of feedback information regarding the channel. Using the bound, it is shown that finite information systems approach the perfect information case as (t-1)2/sup -B/t-1/, where B is the number of feedback bits and t is the number of transmit antennas. The geometrical bounding technique, used in the proof of the lower bound, also leads to a design criterion for good beamformers, whose outage performance approaches the lower bound. The design criterion minimizes the maximum inner product between any two beamforming vectors in the beamformer codebook, and is equivalent to the problem of designing unitary space-time codes under certain conditions. Finally, we show that good beamformers are good packings of two-dimensional subspaces in a 2t-dimensional real Grassmannian manifold with chordal distance as the metric.

MIMO WLAN system

Abstract: A multiple-access MIMO WLAN system that employs MIMO, OFDM, and TDD. The system (1) uses a channel structure with a number of configurable transport channels, (2) supports multiple rates and transmission modes, which are configurable based on channel conditions and user terminal capabilities, (3) employs a pilot structure with several types of pilot (e.g., beacon, MIMO, steered reference, and carrier pilots) for different functions, (4) implements rate, timing, and power control loops for proper system operation, and (5) employs random access for system access by the user terminals, fast acknowledgment, and quick resource assignments. Calibration may be performed to account for differences in the frequency responses of transmit/receive chains at the access point and user terminals. The spatial processing may then be simplified by taking advantage of the reciprocal nature of the downlink and uplink and the calibration.

Receive antenna selection for MIMO spatial multiplexing: theory and algorithms

Abstract: This paper discusses the problem of receive antenna subset selection in multiple-input multiple-output spatial multiplexing (MIMO-SM) systems. We develop selection algorithms for maximizing the channel capacity. One algorithm in particular allows tractable statistical analysis of performance. We leverage this to prove that the capacity of the system through receive antenna selection is statistically lower bounded by the capacity of a set of parallel independent single input multiple output (SIMO) channels, each with selection diversity. This provides the crucial step in proving the next main result: The diversity order achievable through antenna selection is the same as that of the full system. The result sets up strong motivation for introducing receive selection in MIMO-SM systems. The remainder of the paper discusses selection algorithms for two popular MIMO-SM systems, namely, ordered successive interference cancellation with independently encoded layers and minimum mean square error (MMSE) receiver with joint encoding of data streams. Extensive Monte Carlo simulations are presented to validate and demonstrate performance.

MIMO system with multiple spatial multiplexing modes

Abstract: A MIMO system supports multiple spatial multiplexing modes for improved performance and greater flexibility. These modes may include (1) a single-user steered mode that transmits multiple data streams on orthogonal spatial channels to a single receiver, (2) a single-user non-steered mode that transmits multiple data streams from multiple antennas to a single receiver without spatial processing at a transmitter, (3) a multi-user steered mode that transmits multiple data streams simultaneously to multiple receivers with spatial processing at a transmitter, and (4) a multi-user non-steered mode that transmits multiple data streams from multiple antennas (co-located or non co-located) without spatial processing at the transmitter(s) to receiver(s) having multiple antennas. For each set of user terminal(s) selected for data transmission on the downlink and/or uplink, a spatial multiplexing mode is selected for the user terminal set from among the multiple spatial multiplexing modes supported by the system.

Area based position determination for terminals in a wireless network

Abstract: Techniques to estimate the position of a wireless terminal. In a method, the identities of a number of transmitters (e.g., BTSs) to be used to estimate the position are initially received. Expected areas for these transmitters are then determined. The expected area associated with each transmitter is indicative of an area where the terminal is likely to be located given that the signal from the transmitter is received by the terminal. Each expected area may comprise a location (e.g., the expected area center) to be used as an estimated position of the terminal and an uncertainty (or error estimate) associated with that estimated position. The expected areas for the transmitters are then combined (e.g., based on a weighted average) to determine a combined expected area, which is then provided as the estimate of the position of the terminal.

Diversity transmission modes for mimo ofdm communication systems

Abstract: Techniques for transmitting data using a number of diversity transmission modes to improve reliability. At a transmitter, for each of one or more data streams, a particular diversity transmission mode is selected for use from among a number of possible transmission modes. These transmission modes may include a frequency diversity transmission mode, a Walsh diversity transmission mode, a space time transmit diversity (STTD) transmission mode, and a Walsh-STTD transmission mode. Each diversity transmission mode redundantly transmits data over time, frequency, space, or a combination thereof. Each data stream is coded and modulated to provide modulation symbols, which are further processed based on the selected diversity transmission mode to provide transmit symbols. For OFDM, the transmit symbols for all data streams are further OFDM modulated to provide a stream of transmission symbols for each transmit antenna used for data transmission.

Pilots for mimo communication systems

Abstract: Pilots suitable for use in MIMO systems and capable of supporting various functions are described. The various types of pilot include - a beacon pilot, a MIMO pilot, a steered reference or steered pilot, and a carrier pilot. The beacon pilot is transmitted from all transmit antennas and may be used for timing and frequency acquisition. The MIMO pilot is transmitted from all transmit antennas but is covered with different orthogonal codes assigned to the transmit antennas. The MIMO pilot may be used for channel estimation. The steered reference is transmitted on specific eigenmodes of a MIMO channel and is user terminal specific. The steered reference may be used for channel estimation. The carrier pilot may be transmitted on designated subbands/antennas and may be used for phase tracking of a carrier signal. Various pilot transmission schemes may be devised based on different combinations of these various types of pilot.

A communication device for providing multimedia in a group communication network

Abstract: A system and method for providing group communication services is disclosed. Each of a plurality of group communication devices coverts media, such as video, audio, image and/or data into data packets suitable for transmission over a data network, such as the Internet. The data packets are selectively transmitted through the data network to a communications manager. The communications manager acts as a configurable switch, allowing communications from any communication device to be selectively routed to the plurality of communication devices based on the types of the communication devices and/or the requests received from the corresponding users. The communications manager further allows users of other communication systems and devices to participate in group communications with each other.

Multiple-input, multiple-output (mimo) systems with multiple transmission modes

Abstract: Techniques to transmit data on a number of transmission channels in a multi-channel communication system using multiple transmission schemes requiring less channel-state information (CSI). These schemes may include a partial-CSI transmission scheme that transmits a single data stream on each transmit antenna selected for use and a “beam-forming” transmission scheme that allocates all transmit power to a single transmission channel having the best performance. Each transmission scheme may provide good or near-optimum performance for a specific range of operating conditions (or operating SNRs). These multiple transmission schemes may then be combined in a piece-wise fashion to form a “multi-mode” transmission scheme that covers the full range of operating conditions supported by the MIMO system. The specific transmission scheme to be used for data transmission at any given moment would then be dependent on the specific operating condition experienced by the system at that moment.

Triggering event processing

Abstract: Systems, methods, and programs for processing extra data when a triggering event occurs. In one embodiment, an application, triggering event data, and extra data is stored on a wireless device. The wireless device monitors a triggering event parameter associated with an application, such as the expiration of the application. When the triggering event occurs, the wireless device processes the extra data in addition to processing associated with the triggering event data. The extra data may include URLs, scripts or other instructions that involve processing locally to the wireless device or requiring connection to a wireless network for remote processing on other devices.

Transmit diversity processing for a multi-antenna communication system

Abstract: For transmit diversity in a multi-antenna OFDM system, a transmitter encodes, interleaves, and symbol maps traffic data to obtain data symbols. The transmitter processes each pair of data symbols to obtain two pairs of transmit symbols for transmission from a pair of antennas either (1) in two OFDM symbol periods for space-time transmit diversity or (2) on two subbands for space-frequency transmit diversity. N T ·(N T −1)/2 different antenna pairs are used for data transmission, with different antenna pairs being used for adjacent subbands, where N T is the number of antennas. The system may support multiple OFDM symbol sizes. The same coding, interleaving, and modulation schemes are used for different OFDM symbol sizes to simplify the transmitter and receiver processing. The transmitter performs OFDM modulation on the transmit symbol stream for each antenna in accordance with the selected OFDM symbol size. The receiver performs the complementary processing.

Rate control for multi-channel communication systems

Abstract: Techniques to determine a set of rates for a set of data streams to be transmitted in a multi-channel communication system A group of transmission channels to be used for each data stream is initially identified An equivalent system for each group is then defined to have an AWGN (or flat) channel and a spectral efficiency equal to the average spectral efficiency of the transmission channels in the group (216) A metric for each group is then derived based on the associated equivalent system, eg, set to the SNR needed by the equivalent system to support the average spectral efficiency (218) A rate for each data stream is then determined based on the metric associated with the data stream The rate is deemed to be supported by the communication system if the SNR required to support the data rate by the communication system is less than or equal to the metric (226)

A method and an apparatus for adding a new member to an active group call in a group communication network

Abstract: A method and apparatus for adding a member to an active call in a group communication network provides for receiving a member list from a user and sending a request to a server to add the member list to the active group call. The method and apparatus further provides for announcing each member in the member list that they are being added to the group call, receiving acknowledgement from a member who wishes to participate in the group call, and forwarding media to the member. The method and apparatus also provides for a significant reduction in the actual total dormancy wakeup time and latency by exchanging group call signaling even when mobiles are dormant and no traffic channel is active.

Uplink pilot and signaling transmission in wireless communication systems

Abstract: Techniques to more efficiently transmit pilot and signaling on the uplink in an OFDM system. With subband multiplexing, M usable subbands in the system are partitioned into Q disjoint groups of subbands. Each subband group may be assigned to a different terminal for uplink pilot transmission. Multiple terminals may transmit simultaneously on their assigned subbands. The transmit power for the pilot may be scaled higher to attain the same total pilot energy even though S instead of M subbands are used for pilot transmission by each terminal. Pilot transmissions from the terminals are received, and a channel estimate is derived for each terminal based on the pilot received on the assigned subbands. The channel estimate comprises a response for additional subbands not included in the assigned group. Subband multiplexing may also be used for uplink signaling transmission.

Method for extending mobile IP and AAA to enable integrated support for local access and roaming access connectivity

Abstract: This document describes a way to extend Mobile IP Authentication Authorization and Accounting (AAA) signaling to enable a node to request from a network operator combinations of home and local service capabilities (when roaming) in an efficient and scalable manner. It also enables the home and foreign service providers to constrain and account for actual services provided based on a combination of the foreign and home operator policy.

Ofdm communication system with multiple ofdm symbol sizes

Abstract: System traffic may be arranged into different categories (e.g., control data, user data, and pilot data). For each category, one or more OFDM symbols of the proper sizes may be selected for use based on the expected payload size for the traffic in that category. For example, control data may be transmitted using OFDM symbols of a first size, user data may be transmitted using OFDM symbols of the first size and a second size, and pilot data may be transmitted using OFDM symbols of a third size or the first size. In one exemplary design, a small OFDM symbol is utilized for pilot and for transport channels used to send control data, and a large OFDM symbol and the small OFDM symbol are utilized for transport channels used to send user data.

Thin film precursor stack for mems manufacturing

Abstract: This invention provides a precursor film stack for use in the production of MEMS devices. The precursor film stack comprises a carrier substrate, a first layer formed on the carrier substrate, a second layer of an insulator material formed on the first layer, and a third layer of a sacrificial material formed on the second layer.

Method for fabricating an interference display unit

Abstract: A method for fabricating an interference display unit is provided. A first plate and a sacrificial layer are formed in order on a substrate and at least two openings are formed in the first plate and the sacrificial layer. A photoresist layer is spin-coated on the sacrificial layer and fills the openings. A photolithographic process patterns the photoresist layer to define a support with an arm. A second plate is formed on the sacrificial layer and posts. The arm's stress is released through a thermal process. The position of the arm is shifted and the distance between the first plate and the second plate is therefore defined. Finally, The sacrificial layer is removed.

Structure of an optical interference display cell

Abstract: A structure of an interference display cell is provided. The cell comprises a first plate and a second plate, wherein a support is located between the first plate and the second plate. The second plate is a deformable and reflective plate. An incident light from one side of the first plate is modulated and only specific frequency light reflects by the second plate. The frequency of the reflected light is related to the distance between the first plate and the second plate. The support has at least one arm. The arm's stress makes the arm hiking upward or downward. The distance between the first plate and the second plate is also changed. Therefore, the frequency of the reflected light is altered.

Optical interference color display and optical interference modulator

Abstract: An optical interference color display is provided. The optical interference color display comprises a color filtering substrate, a patterned support layer, a plurality of first electrodes, a plurality of optical films and a plurality of second electrodes. The patterned support layer and the first electrodes are positioned on the color filtering substrate with the patterned support layer between the first electrodes. The optical films are positioned on the first electrodes. The second electrodes is positioned over the first electrodes and supported through the patterned support layer such that an air gap with identical thickness is produce between every pair of second electrode and first electrode. Using the color filtering substrate to show color images, air gap between the first electrodes and the second electrodes are identical and hence simplifies the manufacturing process.

Position determination for a wireless terminal in a hybrid position determination system

Abstract: Techniques to determine a position estimate for a wireless terminal. An accurate position estimate for the terminal is initially obtained (e.g., based on a first (accurate) position determination sub-system). For each of one or more transmitters (e.g., base stations) in a second (less accurate) position determination sub-system, an 'expected' pseudo-range is computed based on the accurate position estimate for the terminal and the base station location, a 'measured' pseudo-range is also obtained, and a pseudo-range residual is then determined based on the expected pseudo-range and the measured pseudo-range. Thereafter, to determine an updated position estimate for the terminal, measured pseudo-ranges are obtained for a sufficient number of transmitters. The measured pseudo-range for each base station may be corrected based on the associated residual. The updated position estimate is then determined based on the corrected pseudo-ranges for these transmitters.

Method and apparatus for insuring integrity of a connectorized antenna

Abstract: An antenna is provided with an electronic component or circuit that has a value corresponding to properties of the antenna. A read mechanism reads the value and sets an operational status of a transceiver based on the value. In one embodiment, electronic component is a resistor having a value that identifies the antenna properties. A table may be used to correlate resistor values to different types of antennas or sets of antenna properties. Alternatively, the circuit can be embodied in a microchip that provides a response to a challenge sent by the read mechanism. The response encodes the properties of the antenna. The encoding scheme includes values from the challenge. Alternatively, the response is a code that is indexed into a table of antenna properties. In one embodiment, the antenna is connectorized.

Methods and apparatus for extending mobile ip

Abstract: Methods and apparatus for extending Mobile IP to enable a Mobile IP Home Agent to forward to a default proxy MN server when it does not have a current binding for a MN home address. This can be used to route traffic when the MN is absent and to add processes onto the Proxy MN server that enables application intelligence at the Proxy MN server to act on behalf of the MN when the MN so wishes, e.g., substituting for the MN while the MN is in sleep mode or otherwise unavailable.

Upgrading of electronic files including automatic recovery from failures and errors occurring during the upgrade

Abstract: A portable communication device is provided that receives upgrade files via at least one wireless coupling. The contents of the upgrade file include information to repair errors in software components of the portable communication device and/or information to upgrade functions of the portable communication device. The portable communication device automatically upgrades the software components using the upgrade file contents. The portable communication device automatically recovers to an operational state when detecting an error or failure during the automatic upgrade. Further, the portable communication device resumes or reinitiates the automatic upgrade following the error or failure.

Beacon signaling in a wireless system

Abstract: A few high power tones (1506, 1508) used for synchronization and/or other purposes are transmitted in a FDM system (400) during a period of time into a region, e.g., sector (SECTOR 1-Y) of a cell (Cell 1-N), e.g., a symbol transmission time period. During normal data transmission symbol periods, signals are transmitted using at least 10 tones, e.g., per symbol time. Less than 5 high power signals (1506, 1508) are transmitted in a symbol time with at least 80% the maximum total transmitter power used for transmitting into said region being allocated to the high power signals where the maximum total transmitter power is determined from a period of time which may includes one or more data and/or high power tone (1506, 1508) transmission periods. When the high power tones (1506, 1508) are transmitted at most 20% of transmitter power used for transmitting into the region is available for transmitting other tones with the power normally being distributed among multiple tones. Often some tones, which would be transmitted in a symbol time go unused during transmission of the high power signals (1506, 1508).

System and method for application management through threshold events

Abstract: A system, method, and program for managing applications on remote communication devices (1-6), such as cellular telephones, on a wireless communications network (100). A server (112) on the wireless network (100) stores application threshold event data and manages communication device resident applications through device interaction, such as limiting access to server-side applications, updating the application, or recording the occurrence of the threshold event for other application uses.

A method and an apparatus for terminating a user from a group call in a group communication network

Abstract: A method and apparatus for terminating a member from a group call in a group communication network provides for receiving an indication from a user who wishes to terminate participation in a group call and sending a request to a server to terminate the user from the group call. The method and apparatus further provides for the server to receive the request for terminating a user from a group call, terminate the user from the group call, and send a response indicating that the user is terminated from the group call.