Sassan Iraji

Bio: Sassan Iraji is an academic researcher from Nokia. The author has contributed to research in topics: Transmission (telecommunications) & Communication channel. The author has an hindex of 11, co-authored 19 publications receiving 422 citations. Previous affiliations of Sassan Iraji include Nokia Networks.

License-exempt LTE deployment in heterogeneous network

Abstract: Mobile broadband data usage in Long Term Evolution (LTE) networks is growing exponentially and capacity constraint is becoming an issue. Heterogeneous network, WiFi offload, and acquisition of additional radio spectrum can be used to address this capacity constraint. Licensed spectrum, however, is limited and can be costly to obtain. This paper investigates deploying LTE on a license-exempt band as part of the pico-cell underlay. Coexistence mechanism and other modifications to LTE are discussed. Performance analysis shows that LTE can deliver significant capacity even while sharing the spectrum with WiFi systems.

Method, device, and system for "listen-before-talk" measurement to enable identifying of one or more unoccupied RF sub-bands

Abstract: The invention relates to a method of performing a Listen-Before-Talk measurement to enable identifying of one or more unoccupied radio frequency sub-bands applicable for radio frequency identification (RFID) communication operable with a radio frequency identification (RFID) reader subsystem; said method comprising obtaining timing information relating to one or more periods of activity of a wireless communication subsystem; deriving information about one or more periods of non-activity from said timing information; configuring said wireless communication subsystem to perform said Listen-Before-Talk measurement in coordination with said one or more periods of non-activity; and performing said Listen-Before-Talk measurement by the means of the wireless communication subsystem to identify said one or more unoccupied radio frequency sub-bands.

Advanced coding schemes for a multiband OFDM ultrawideband system towards 1 Gbps

Abstract: Advanced coding schemes such as parallel concatenated zigzag (PCZZ) and LDPC codes are shown to provide performance close to turbo codes. In this paper we propose PCZZ and structured LDPC coding for an MB-OFDM UWB system with 16-QAM modulation aiming at increasing the data rate of the current system up to 1 Gbps. We evaluate the performance of the PCZZ and LDPC coding schemes in such a system. In particular, it is shown that the PCZZ and LDPC codes provide 3-4 dB gain in packet error rate compared to convolutional codes. We also address the link budget and achievable ranges for such a system with different coding rates. The proposed PCZZ and structured LDPC codes may be considered as a potential channel coding scheme for the future Multiband OFDM UWB systems providing data rates up to 1 Gbps or higher.

Codebooks for mobile communications

Abstract: Methods, computer program products, and apparatus are disclosed performing the following: receiving a codebook; receiving one or more modifiers corresponding to the codebook; determining which portion of the codebook is to be applied to information to be transmitted; applying the portion of the codebook to the information to determine coded information; using the one or more modifiers, modifying one or more metrics; determining transmit power to be used for transmission of the coded information by using a selected one of the one or more modified metrics corresponding to the portion of the codebook; and transmitting the coded information.

An apparatus comprising a radio antenna element and a grounded conductor

Abstract: An apparatus comprising: an exterior housing; a radio antenna element within the exterior housing; and a grounded conductor extending adjacent the antenna element and having a first area that is physically associated with a portion of the exterior housing.

LTE-unlicensed: the future of spectrum aggregation for cellular networks

Abstract: The phenomenal growth of mobile data demand has brought about increasing scarcity in available radio spectrum. Meanwhile, mobile customers pay more attention to their own experience, especially in communication reliability and service continuity on the move. To address these issues, LTE-Unlicensed, or LTEU, is considered one of the latest groundbreaking innovations to provide high performance and seamless user experience under a unified radio technology by extending LTE to the readily available unlicensed spectrum. In this article, we offer a comprehensive overview of the LTEU technology from both operator and user perspectives, and examine its impact on the incumbent unlicensed systems. Specifically, we first introduce the implementation regulations, principles, and typical deployment scenarios of LTE-U. Potential benefits for both operators and users are then discussed. We further identify three key challenges in bringing LTE-U into reality together with related research directions. In particular, the most critical issue of LTE-U is coexistence with other unlicensed systems, such as widely deployed WiFi. The LTE/WiFi coexistence mechanisms are elaborated in time, frequency, and power aspects, respectively. Simulation results demonstrate that LTE-U can provide better user experience to LTE users while well protecting the incumbent WiFi users’ performance compared to two existing advanced technologies: cellular/WiFi interworking and licensed-only heterogeneous networks (Het-Nets).

Adjustable wireless circuitry with antenna-based proximity detector

Abstract: An electronic device such as a portable electronic device has wireless communications circuitry. Antennas in the electronic device may be used in transmitting radio-frequency antenna signals. A coupler and antenna signal phase and magnitude measurement circuitry may be used to determine when external objects are in the vicinity of the antenna by making antenna impedance measurements. In-band and out-of-band phase and magnitude signal measurements may be made in determining whether external objects are present. Additional sensors such as motion sensors, light and heat sensors, acoustic and electrical sensors may produce data that can be combined with the proximity data gathered using the antenna-based proximity sensor. In response to detecting that an external object such as a user's body is within a given distance of the antenna, the electronic device may reduce transmit powers, switch antennas, steer a phased antenna array, switch communications protocols, or take other actions.

Performance Evaluation of LTE and Wi-Fi Coexistence in Unlicensed Bands

Abstract: The deployment of modern mobile systems has faced severe challenges due to the current spectrum scarcity. The situation has been further worsened by the development of different wireless technologies and standards that can be used in the same frequency band. Furthermore, the usage of smaller cells (e.g. pico, femto and wireless LAN), coexistence among heterogeneous networks (including amongst different wireless technologies such as LTE and Wi-Fi deployed in the same frequency band) has been a big field of research in the academy and industry. In this paper, we provide a performance evaluation of coexistence between LTE and Wi-Fi systems and show some of the challenges faced by the different technologies. We focus on a simulator-based system- level analysis in order to assess the network performance in an office scenario. Simulation results show that LTE system performance is slightly affected by coexistence whereas Wi-Fi is significantly impacted by LTE transmissions. In coexistence, the Wi-Fi channel is most often blocked by LTE interference, making the Wi-Fi nodes to stay on the LISTEN mode more than 96% of the time. This reflects directly on the Wi-Fi user throughput, that decreases from 70% to ≈100% depending on the scenario. Finally, some of the main issues that limit the LTE/Wi-Fi coexistence and some pointers on the mutual interference management of both the systems are provided.

5G Mobile: Spectrum Broadening to Higher-Frequency Bands to Support High Data Rates

Abstract: Next-generation [fifth-generation (5G)] mobile systems are broadening their spectrum to higher-frequency bands (above 6 GHz) to support a high data rate up to multigigabits per second. In this article, we have two main contributions to higher-frequency communications. First, we summarize the candidate frequency bands that are promising for 5G research, including licensed and unlicensed frequency bands. Second, a new network architecture for higher-frequency communications is proposed, which is featured with load-centric backhauling (LCB), multiple-frequency transmission, and intelligent control techniques.

Electronic device with proximity-based radio power control

Abstract: An electronic device such as a portable electronic device may have an antenna and associated wireless communications circuitry. A sensor such as a proximity sensor may be used to detect when the electronic device is in close proximity to a user's head. Control circuitry within the electronic device may be used to adjust radio-frequency signal transmit power levels. When it is determined that the electronic device is within a given distance from the user's head, the radio-frequency signal transmit power level may be reduced. When it is determined that the electronic device is not within the given distance from the user's head, proximity-based limits on the radio-frequency signal transmit power level may be removed. Data may be gathered from a touch sensor, accelerometer, ambient light sensor and other sources for use in determining how to adjust the transmit power level.