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Author

Farooq Khan

Other affiliations: Ericsson, Alcatel-Lucent
Bio: Farooq Khan is an academic researcher from Samsung. The author has contributed to research in topics: Base station & Wireless network. The author has an hindex of 47, co-authored 267 publications receiving 9745 citations. Previous affiliations of Farooq Khan include Ericsson & Alcatel-Lucent.


Papers
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Journal ArticleDOI
Zhouyue Pi1, Farooq Khan1
TL;DR: This article introduces a millimeter-wave mobile broadband (MMB) system as a candidate next generation mobile communication system and demonstrates the feasibility for MMB to achieve gigabit-per-second data rates at a distance up to 1 km in an urban mobile environment.
Abstract: Almost all mobile communication systems today use spectrum in the range of 300 MHz-3 GHz. In this article, we reason why the wireless community should start looking at the 3-300 GHz spectrum for mobile broadband applications. We discuss propagation and device technology challenges associated with this band as well as its unique advantages for mobile communication. We introduce a millimeter-wave mobile broadband (MMB) system as a candidate next generation mobile communication system. We demonstrate the feasibility for MMB to achieve gigabit-per-second data rates at a distance up to 1 km in an urban mobile environment. A few key concepts in MMB network architecture such as the MMB base station grid, MMB interBS backhaul link, and a hybrid MMB + 4G system are described. We also discuss beamforming techniques and the frame structure of the MMB air interface.

2,487 citations

Book
Farooq Khan1
01 Mar 2009
TL;DR: In this paper, the authors present a practical and valuable guide to the new technologies of the LTE standard and how they contribute to improvements in system performance with the help of an expert who was intimately involved in drafting the standard.
Abstract: Do you need to get up to speed quickly on LTE? Understand the new technologies of the LTE standard and how they contribute to improvements in system performance with this practical and valuable guide, written by an expert on LTE who was intimately involved in drafting the standard. In addition to a strong grounding in the technical details, you'll also get fascinating insights into why particular technologies were chosen in the development process. Core topics covered include: Network architecture and protocols OFDMA downlink access Low-PAPR SC-FDMA uplink access Transmit diversity and MIMO spatial multiplexing Channel structure and bandwidths Cell search, reference signals and random access Turbo coding with contention-free interleaver Scheduling, link adaptation, hybrid ARQ and power control Uplink and downlink physical control signaling Inter-cell interference mitigation techniques Single-frequency network (SFN) broadcast MIMO spatial channel model Evaluation methodology and system performance With extensive references, a useful discussion of technologies that were not included in the standard, and end-of-chapter summaries that emphasize all the key points, this book is an essential resource for practitioners in the mobile cellular communications industry and for graduate students studying advanced wireless communications.

514 citations

Patent
Farooq Khan1, Zhouyue Pi1
05 Apr 2011
TL;DR: In this article, an apparatus and method for full-duplex millimeter-wave mobile wireless communication are provided, which includes a Spatial Division Duple (SDD) mobile communication system using millimeter waves.
Abstract: An apparatus and method for full-duplex millimeter wave mobile wireless communication are provided. The apparatus includes a Spatial Division Duple(SDD) mobile communication system using millimeter waves, the SDD mobile communication system including a first wireless terminal having a first transmit antenna array having a plurality of first transmit antennas for transmitting a spatially beamformed first transmit beam, and a first receive antenna array having a plurality of first receive antennas for forming a spatially beamformed first receive beam and a second wireless terminal including a second transmit antenna array having a plurality of second transmit antennas for transmitting a spatially beamformed second transmit beam directed towards a receive beam of the first wireless terminal, and a second receive antenna array having a plurality of second receive antennas for forming a spatially beamformed second receive beam directed toward the transmit beam of the first terminal.

241 citations

Proceedings ArticleDOI
Farooq Khan1, Zhouyue Pi1
03 May 2011
TL;DR: This paper reason why wireless community should start looking at 3–300GHz spectrum for mobile broadband applications as well as its unique advantages such as spectrum availability and small component sizes for mobile applications.
Abstract: Almost all cellular mobile communications including first generation analog systems, second generation digital systems, third generation WCDMA, and fourth generation OFDMA systems use Ultra High Frequency (UHF) band of radio spectrum with frequencies in the range of 300MHz-3GHz. This band of spectrum is becoming increasingly crowded due to spectacular growth in mobile data and other related services. The portion of the RF spectrum above 3GHz has largely been uxexploited for commercial mobile applications. In this paper, we reason why wireless community should start looking at 3–300GHz spectrum for mobile broadband applications. We discuss propagation and device technology challenges associated with this band as well as its unique advantages such as spectrum availability and small component sizes for mobile applications.

167 citations

Patent
29 May 2008
TL;DR: In this paper, a method for feedback and transmission of multi-user (MU) multiple input multiple output (MIMO) in a wireless communication system is presented, which includes steps of selecting subset codebook or full code book based on traffic load of a base station, and broadcasting the selected codebook to user equipments.
Abstract: The present invention provides a method for feedback and transmission of multi-user (MU) multiple input multiple output (MIMO) in a wireless communication system. The method includes steps of selecting subset codebook or full code book based on traffic load of a base station, and broadcasting the selected codebook to user equipments. In high traffic load, subset codebook is selected, and in low traffic load, full codebook is selected. User stations calculated a channel quality indicator of a spatial codeword vector that is included in the selected codebook. Information of the maximum channel quality indicator is sent to the base station together with a precoder of the user equipment. The base station selects user equipments based on the information of the maximum channel quality indicator and precoder, and transmits precoder signal and data signal to the user equipments. The present invention also provides a system for the base station that causes the base station to perform the above mentioned operations.

165 citations


Cited by
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Journal ArticleDOI
TL;DR: This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.
Abstract: What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

7,139 citations

Journal ArticleDOI
TL;DR: The motivation for new mm-wave cellular systems, methodology, and hardware for measurements are presented and a variety of measurement results are offered that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.
Abstract: The global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm-wave) frequency spectrum for future broadband cellular communication networks. There is, however, little knowledge about cellular mm-wave propagation in densely populated indoor and outdoor environments. Obtaining this information is vital for the design and operation of future fifth generation cellular networks that use the mm-wave spectrum. In this paper, we present the motivation for new mm-wave cellular systems, methodology, and hardware for measurements and offer a variety of measurement results that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.

6,708 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe five technologies that could lead to both architectural and component disruptive design changes: device-centric architectures, millimeter wave, massive MIMO, smarter devices, and native support for machine-to-machine communications.
Abstract: New research directions will lead to fundamental changes in the design of future fifth generation (5G) cellular networks. This article describes five technologies that could lead to both architectural and component disruptive design changes: device-centric architectures, millimeter wave, massive MIMO, smarter devices, and native support for machine-to-machine communications. The key ideas for each technology are described, along with their potential impact on 5G and the research challenges that remain.

3,711 citations

Journal ArticleDOI
TL;DR: This paper considers transmit precoding and receiver combining in mmWave systems with large antenna arrays and develops algorithms that accurately approximate optimal unconstrained precoders and combiners such that they can be implemented in low-cost RF hardware.
Abstract: Millimeter wave (mmWave) signals experience orders-of-magnitude more pathloss than the microwave signals currently used in most wireless applications and all cellular systems. MmWave systems must therefore leverage large antenna arrays, made possible by the decrease in wavelength, to combat pathloss with beamforming gain. Beamforming with multiple data streams, known as precoding, can be used to further improve mmWave spectral efficiency. Both beamforming and precoding are done digitally at baseband in traditional multi-antenna systems. The high cost and power consumption of mixed-signal devices in mmWave systems, however, make analog processing in the RF domain more attractive. This hardware limitation restricts the feasible set of precoders and combiners that can be applied by practical mmWave transceivers. In this paper, we consider transmit precoding and receiver combining in mmWave systems with large antenna arrays. We exploit the spatial structure of mmWave channels to formulate the precoding/combining problem as a sparse reconstruction problem. Using the principle of basis pursuit, we develop algorithms that accurately approximate optimal unconstrained precoders and combiners such that they can be implemented in low-cost RF hardware. We present numerical results on the performance of the proposed algorithms and show that they allow mmWave systems to approach their unconstrained performance limits, even when transceiver hardware constraints are considered.

3,146 citations

Journal ArticleDOI
TL;DR: This survey makes an exhaustive review of wireless evolution toward 5G networks, including the new architectural changes associated with the radio access network (RAN) design, including air interfaces, smart antennas, cloud and heterogeneous RAN, and underlying novel mm-wave physical layer technologies.
Abstract: The vision of next generation 5G wireless communications lies in providing very high data rates (typically of Gbps order), extremely low latency, manifold increase in base station capacity, and significant improvement in users’ perceived quality of service (QoS), compared to current 4G LTE networks. Ever increasing proliferation of smart devices, introduction of new emerging multimedia applications, together with an exponential rise in wireless data (multimedia) demand and usage is already creating a significant burden on existing cellular networks. 5G wireless systems, with improved data rates, capacity, latency, and QoS are expected to be the panacea of most of the current cellular networks’ problems. In this survey, we make an exhaustive review of wireless evolution toward 5G networks. We first discuss the new architectural changes associated with the radio access network (RAN) design, including air interfaces, smart antennas, cloud and heterogeneous RAN. Subsequently, we make an in-depth survey of underlying novel mm-wave physical layer technologies, encompassing new channel model estimation, directional antenna design, beamforming algorithms, and massive MIMO technologies. Next, the details of MAC layer protocols and multiplexing schemes needed to efficiently support this new physical layer are discussed. We also look into the killer applications, considered as the major driving force behind 5G. In order to understand the improved user experience, we provide highlights of new QoS, QoE, and SON features associated with the 5G evolution. For alleviating the increased network energy consumption and operating expenditure, we make a detail review on energy awareness and cost efficiency. As understanding the current status of 5G implementation is important for its eventual commercialization, we also discuss relevant field trials, drive tests, and simulation experiments. Finally, we point out major existing research issues and identify possible future research directions.

2,624 citations