The Experts below are selected from a list of 1845 Experts worldwide ranked by ideXlab platform

Daniela Tuninetti - One of the best experts on this subject based on the ideXlab platform.

  • 1On the Benefits of Partial Channel State Information for Repetition Protocols in Block Fading Channels
    2016
    Co-Authors: Daniela Tuninetti
    Abstract:

    This paper studies the throughput performance of HARQ (hybrid automatic repeat request) protocols over block fading Gaussian Channels. It proposes new protocols that use the available feedback bit(s) not only to request a retransmission, but also to inform the transmitter about the Instantaneous Channel Quality. An explicit protocol construction is given for any number of retransmissions and any number of feedback bits. The novel protocol is shown to simultaneously realize the gains of HARQ and of power control with partial CSI (Channel state information). Remarkable throughput improvements are shown, especially at low and moderate SNR (signal to noise ratio), with respect to protocols that use the feedback bits for retransmission request only. In particular, for the case of a single retransmission and a single feedback bit, it is shown that the repetition is not needed at low SNR where the throughput improvement is due to power control only. On the other hand, at high SNR, the repetition is useful and the performance gain comes form a combination of power control and ability of make up for deep fades

  • On the Benefits of Partial Channel State Information for Repetition Protocols in Block Fading Channels
    IEEE Transactions on Information Theory, 2011
    Co-Authors: Daniela Tuninetti
    Abstract:

    This paper studies the throughput performance of HARQ (hybrid automatic repeat request) protocols over block fading Gaussian Channels. It proposes new protocols that use the available feedback bit(s) not only to request a retransmission, but also to inform the transmitter about the Instantaneous Channel Quality. An explicit protocol construction is given for any number of retransmissions and any number of feedback bits. The novel protocol is shown to simultaneously realize the gains of HARQ and of power control with partial CSI (Channel state information). Remarkable throughput improvements are shown, especially at low and moderate SNR (signal to noise ratio), with respect to protocols that use the feedback bits for retransmission request only. In particular, for the case of a single retransmission and a single feedback bit, it is shown that the repetition is not needed at low $\snr$ where the throughput improvement is due to power control only. On the other hand, at high SNR, the repetition is useful and the performance gain comes form a combination of power control and ability of make up for deep fades.

Jawatankuasa Kerja Psm Utem - One of the best experts on this subject based on the ideXlab platform.

  • Design and analysis of modified-proportional fair scheduler for LTE/LTE-advanced in single cell networks
    Journal of Telecommunication Electronic and Computer Engineering Universiti Teknikal Malaysia Melaka, 2017
    Co-Authors: Jawatankuasa Kerja Psm Utem
    Abstract:

    Nowadays, Long Term Evolution-Advanced (LTE-A) is well known as a cellular network that can support very high data rates in diverse traffic conditions. One way of achieving it is through packet scheduling which is the key scheme of Radio Resource Management (RRM) for LTE-A traffic processing that is functioning to allocate resources for both frequency and time dimensions. The main contribution of this paper is the design of a new scheduling scheme and its performance is compared with the Proportional Fair (PF) and Round Robin (RR) downlink schedulers for LTE-A by utilizing LTE-A Downlink System Level Simulator in femto cell for indoor coverage extension. The proposed new scheduling algorithm, namely the Modified-PF scheduler divides a single sub-frame into multiple time slots and allocates the resource block (RB) to the targeted User Equipment (UE) in all time slots of each sub-frame based on the Instantaneous Channel Quality Indicator (CQI) feedback received from UEs. Simulation results show that the Modified-PF scheduler provides the best performance in terms of throughput and spectral efficiency. The Modified-PF scheduler provides a better compromise between the throughput and spectral efficiency. This shows that the newly proposed scheme improves the LTE output performances while at the same time maintains minimal required fairness among the UEs

  • Design and analysis of modified-proportional fair scheduler for LTE femtocell networks
    Journal of Telecommunication Electronic and Computer Engineering Universiti Teknikal Malaysia Melaka, 2016
    Co-Authors: Jawatankuasa Kerja Psm Utem
    Abstract:

    Nowadays, Long Term Evolution-Advanced (LTEA) is well known as a cellular network that can support very high data rates in diverse traffic conditions. One way of achieving it is through packet scheduling which is the key scheme of Radio Resource Management (RRM) for LTE-A traffic processing that is functioning to allocate resources for both frequency and time dimensions. The main contribution of this paper is the design of a new scheduling scheme and its performance is compared with the Proportional Fair (PF) and Round Robin (RR) downlink schedulers for LTE-A by utilizing LTE-A Downlink System Level Simulator in femto cell for indoor coverage extension. The proposed new scheduling algorithm, namely the Modified-PF scheduler divides a single sub-frame into multiple time slots and allocates the resource block (RB) to the targeted User Equipment (UE) in all time slots for each sub-frame based on the Instantaneous Channel Quality Indicator (CQI) feedback received from UEs. Simulation results show that the Modified-PF scheduler provides the best performance in terms of throughput and spectral efficiency. The Modified-PF scheduler provides a better compromise between the throughput and spectral efficiency. This shows that the newly proposed scheme improves the LTE output performances while at the same time maintains minimal required fairness among the UEs

Jungwoo Lee - One of the best experts on this subject based on the ideXlab platform.

  • low complexity mimo scheduling with Channel decomposition using capacity upperbound
    Wireless Communications and Networking Conference, 2008
    Co-Authors: Xiaojie Zhang, Jungwoo Lee
    Abstract:

    In multiuser MIMO systems, the base station schedules transmissions to a group of users simultaneously. Since the data transmitted to each user are different, in order to avoid the inter-user interference, a transmit preprocessing technique which decomposes the multiuser MIMO downlink Channel into multiple parallel independent single-user MIMO Channels can be used. When the number of users is larger than the maximum that the system can support simultaneously, the base station selects a subset of users who have the best Instantaneous Channel Quality to maximize the system throughput. Since the exhaustive search for the optimal user set is computationally prohibitive, a low complexity scheduling algorithm which aims to maximize the capacity upper bound is proposed. Simulation results show that the proposed scheduling algorithm achieves comparable total throughput as the optimal algorithm with much lower complexity.

Rajiv Laroia - One of the best experts on this subject based on the ideXlab platform.

  • opportunistic beamforming using dumb antennas
    International Symposium on Information Theory, 2002
    Co-Authors: Pramod Viswanath, David Tse, Rajiv Laroia
    Abstract:

    Multiuser diversity is a form of diversity inherent in a wireless network, provided by independent time-varying Channels across the different users. The diversity benefit is exploited by tracking the Channel fluctuations of the users and scheduling transmissions to users when their Instantaneous Channel Quality is near the peak. The diversity gain increases with the dynamic range of the fluctuations and is thus limited in environments with little scattering and/or slow fading. In such environments, we propose the use of multiple transmit antennas to induce large and fast Channel fluctuations so that multiuser diversity can still be exploited. The scheme can be interpreted as opportunistic beamforming and we show that true beamforming gains can be achieved when there are sufficient users, even though very limited Channel feedback is needed. Furthermore, in a cellular system, the scheme plays an additional role of opportunistic nulling of the interference created on users of adjacent cells. We discuss the design implications of implementing. this scheme in a complete wireless system.

Mohd Riduan Ahmad - One of the best experts on this subject based on the ideXlab platform.

  • Design And Development Of Modified-Proportional Fair Scheduler For LTE/LTE-Advanced
    Asian Research Publishing Network (ARPN), 2016
    Co-Authors: Mohd Khairy Ismail, Azmi, Awang Md Isa, Mohd Nor Husain, Muhammad Syahrir Johal, Mohd Riduan Ahmad
    Abstract:

    Long Term Evolution (LTE) is well known as a cellular network that can support very high data rates in diverse traffic conditions. One way of achieving it is through packet scheduling which is the key scheme of Radio Resource Management (RRM) for LTE traffic processing that is functioning to allocate resources for both frequency and time dimensions. The main contribution of this paper is the design of a new scheduling scheme and its performance is compared with the Proportional Fair (PF) and Round Robin (RR) downlink schedulers for LTE by utilizing LTE Downlink System Level Simulator. The proposed new scheduling algorithm, namely the Modified-PF scheduler divides a single subframe into multiple time slots and allocates the resource block (RB) to the targeted User Equipment (UE) in all time slots for each subframe based on the Instantaneous Channel Quality Indicator (CQI) feedback received from UEs. Simulation results show that the Modified-PF scheduler provides the best performance in terms of throughput and spectral efficiency with comparale fairness as compared to RR and PF schedulers. Although PF scheduler has the best fairness index, the Modified-PF scheduler provides a better compromise between the throughput/spectral efficiency and fairness. This shows that the newly proposed scheme improves the LTE output performances while at the same time maintains minimal required fairness among the UEs