Showing papers by "Amitava Ghosh published in 2006"

Uplink Power Control, Interference Coordination and Resource Allocation for 3GPP E-UTRA

Abstract: Evolved UTRA and UTRAN is being standardized in 3GPP standard group as a long term evolution of the 3GPP radio-access technology. The goal is to achieve 2-4 times the spectral efficiency and user throughput and much smaller latency compared to HSDPA/HSUPA. Single carrier FDMA (e.g. DFT-SOFDM) is the multiple access technique of choice for uplink transmission. Interference control is one of the key elements to achieve the target spectral efficiency and user cell- edge performance requirement, especially for uplink. In this paper, interference mitigation is implemented through slow fractional power control and interference coordination through UE alignment and FDM resource allocation. Simulation results show that these techniques significantly improve uplink sector and cell edge user throughput performance.

Method and apparatus for providing channel quality feedback in an orthogonal frequency division multiplexing communication system

Abstract: In an Orthogonal Frequency Division Multiplexing communication system, a user equipment reports channel quality information that is sufficient to construct a fading profile of a frequency bandwidth and that does not consuming the overhead resulting from the reporting of CQI for every sub-band of the frequency bandwidth. In the communication system, the frequency bandwidth may be represented by multiple sub-band levels, wherein each sub-band level comprises a division of the frequency bandwidth into a number of sub-bands different from the number of sub-bands of the other sub-band levels. The user equipment measures a channel quality associated with each sub-band of a sub-band level of the multiple sub-band levels, selects a sub-band of the sub-band level based on the measured channel qualities, and reports channel quality information associated with the selected sub-band to a radio access network.

Handover in a cellular communication system

Abstract: A cellular communication system includes first (103) and Second (105) base stations and an user equipment (101). A Radio Network Controller controls a handover of the user equipment between the base stations by either forwarding data of the communication to both the first and second base stations or to only one of the first and second base stations dependent on a Quality of Service (QoS) characteristic of the communication of the user equipment. The QoS characteristic can specifically be an indication of a delay constraint for the communication service such as an indication of whether the service is a real-time service or a non-real time service.

WiMAX Overview and System Performance

Abstract: In this paper, the performance of WiMax network with DL SIMO, DL MIMO and UL SIMO is analyzed via system simulations Two data traffic models are considered, namely Web browsing (HTTP) and full buffer sessions, operating in multi path fading channels such as the ITU pedestrian-B and vehicular-A channels The control channel coverage and reliability of WiMAX using realistic overhead is also analyzed in this paper

Transmission technique selector for radio communication systems with multiple transmit and multiple receive antennas

Abstract: A radio communications device ( 102 ) that has multiple receive antennas processes received data communications signals to select between space time coding and spatial multiplexing as a selected transmission technique from a base device ( 104 ) that has multiple transmit antennas. A channel throughput ( 402 - 412, 450 - 454 ) for each transmission technique is estimated based on signal to interference and noise ratios ( 502 - 512, 550 - 554 ) of signals being transmitted through a MIMO channel ( 140 ) as measured by a receiver ( 708 ). The transmission technique with the higher estimated throughput is determined. If spatial multiplexing is determined to have the higher estimated throughput and the throughput of each layer of the spatially multiplexed signal is greater than a threshold, spatial multiplexing is selected. Otherwise, space time coding is selected.

Method and apparatus for ifdma transmission

Abstract: Various embodiments are described to provide for the transmission of data in an improved manner. Data transmission is improved by including in a transmitter a null generator to embed frequency domain nulls into a data symbol sequence to produce a null-embedded data symbol sequence. A symbol inserter inserts a control symbol sequence into the frequency domain nulls of the null-embedded data symbol sequence to produce a combined symbol sequence. A modulator then encodes the combined symbol sequence using IFDMA/DFT-S-OFDM. This approach allows the assignment of a single IFDMA/DFT-S-OFDM code to each user for data and control (pilot, e.g.) signaling, simplifying code management. Frequency hopping techniques may also be employed to lower the pilot overhead.

A transmitter, cellular communication system and method of transmitting therefor

Abstract: A transmitter comprises functionality (101, 103) for generating a block of input modulation symbols for example from received data bits. An M-point discrete Fourier transform (105) is applied to the block of input modulation symbols resulting in a frequency domain symbol block. This block is fed to an N-point inverse discrete Fourier transform (105) (N>M) thereby generating a time domain transmit signal. In addition, the transmitter (200) comprises an inter-symbol processor (201) which determines inter-symbol values corresponding to inter-symbol times of the time domain transmit signal and an attenuation processor (203) which attenuates at least one of the input modulation symbols in response to the inter-symbol values. By attenuating selected input modulation symbol(s) a significantly reduced amplitude variation and specifically peak-to-average amplitude variation can be achieved.

Symbol mapping and pilot insertion in an OFDM-CDMA system

Abstract: Various embodiments are described to provide for the transmission and reception of data in an improved manner. Data transmission is improved by including in a transmitter a null generator (110) to generate an output data symbol sequence that exhibits nulls in the frequency domain at particular frequencies that an input data symbol sequence does not. A pilot inserter (120) then adds a pilot symbol sequence to this output data symbol sequence to create a combined symbol sequence. Since the pilot symbol sequence exhibits pilot signals corresponding to the nulls of the output data symbol sequence in the frequency domain, the combined symbol sequence exhibits pilots that are orthogonal to the data in the frequency domain. Application to a hybrid OFDM-CDMA system where spreading is performed in the time domain.

Method and apparatus for ifdma/dft-s-ofdm transmission

Abstract: Various embodiments are described to provide for the transmission of data in an improved manner. Data transmission is improved by including in a transmitter a null generator (310) to embed frequency domain nulls into a data symbol sequence to produce a null-embedded data symbol sequence. A symbol inserter (320) inserts a control symbol sequence into the frequency domain nulls of the null-embedded data symbol sequence to produce a combined symbol sequence. A modulator (330) then encodes the combined symbol sequence using IFDMA / DFT-S-OFDM. This approach allows the assignment of a single IFDMA / DFT-S-OFDM code to each user for data and control (pilot, e.g.) signaling, simplifying code management. Frequency hopping techniques may also be employed to lower the pilot overhead.