Conference Paper

Spectral Efficiency and Fairness for Opportunistic Round Robin Scheduling

Norwegian University of Science and Technology, Dept. of Electronics and Telecommunications, 7491 Trondheim, Norway, email:
DOI: 10.1109/ICC.2006.254803 Conference: Communications, 2006. ICC '06. IEEE International Conference on, Volume: 2
Source: IEEE Xplore

ABSTRACT In this paper we analyze the Opportunistic Round Robin (ORR) scheduling algorithm [1], [2]. This algorithm is able to exploit multiuser diversity (MUD) and at the same time provide short-term fairness between the users in a wireless cellular network. We analyze the spectral efficiency and the fairness for two scenarios. In the first scenario all the users have the same average carrier-to-noise ratios (CNR) and for the second scenario the users have different average CNRs. For the first scenario the absolute MUD is exploited while we exploit the so-called relative MUD between the users for the second scenario. The advantages and disadvantages of the different ORR implementations are highlighted by analyzing plots of our closed-form expressions.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We consider a wireless sensor network that comprises a single hop between the sensor nodes and the central controller node with multiple antennas. In this system model, we concentrate on the single-beam opportunistic communication and propose two novel packet transmission schemes that can perform multiuser diversity gain based on the signal-to-noise ratio (SNR) and the normalized SNR (NSNR) measurements at the sensor nodes with single antenna. The main objective of the multiuser diversity is to increase the total throughput over the fast fading channels. Proposed schemes are based on the principle of cross-layer design that integrates with physical layer characteristics of wireless channel and medium access control (MAC) layer characteristics of network. In our design, we assume that the sensor nodes know only their own channels to the controller node and the packet transfer from the sensor nodes to the controller node is initiated when the channel quality of any node exceeds the predefined threshold at the current time slot. To determine the optimum threshold, we maximize the probability of successful packet transmission where only one sensor node transmits its packet in one time slot under the simplified collision model. Simulation results are demonstrated to compare the performance of the proposed schemes in terms of throughput, energy efficiency, and fairness. The obtained results show that the presented opportunistic strategy can be used to improve the network throughput.
    International Journal of Distributed Sensor Networks 09/2012; 2012. · 0.92 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper we evaluate a recently proposed multiple-input multiple-output (MIMO) system called the Layered Steered Space-Time Codes (LSSTC). The LSSTC system is evaluated for multi-user environments where scheduling can be used to increase the system capacity by harnessing the multi-user diversity. This evaluation is done by comparing the capacity and the probability of error for several combinations of algorithms and criteria for scheduling users' data. The results obtained show that many of the scheduling criteria derived in literature does not perform well with the LSSTC system. Instead, a scheduling criterion that directly coincides with the detection mechanism of the LSSTC receiver is derived. This scheduling criterion can jointly maximize the capacity and minimize the error probability. Also we derive a formula for the PDF of the maximum preprocessing SNR for a Greedy-based multi-user LSSTC.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Base station (BS) sleeping has emerged as a viable solution to enhance the overall network energy efficiency by inactivating the underutilized BSs. However, it affects the performance of users in sleeping cells depending on their BS association criteria, their channel conditions towards the active BSs, and scheduling criteria and traffic loads at the active BSs. This paper characterizes the performance of cellular systems with BS sleeping by developing a systematic framework to derive the spectral efficiency and outage probability of downlink transmission to the sleeping cell users taking into account the aforementioned factors. In this context, we develop a user association scheme in which a typical user in a sleeping cell selects a BS with \textbf{M}aximum best-case \textbf{M}ean channel \textbf{A}ccess \textbf{P}robability (MMAP) which is calculated by all active BSs based on their existing traffic loads. We consider both greedy and round-robin schemes at active BSs for scheduling users in a channel. Once the association is performed, the exact access probability for a typical sleeping cell user and the statistics of its received signal and interference powers are derived to evaluate the spectral and energy efficiencies of transmission. For the sleeping cell users, we also consider the conventional \textbf{M}aximum \textbf{R}eceived \textbf{S}ignal \textbf{P}ower (MRSP)-based user association scheme along with greedy and round-robin schemes at the BSs. The impact of cell-zooming is incorporated in the derivations to analyze its feasibility in reducing the coverage holes created by BS sleeping. Numerical results show the trade-offs between spectral efficiency and energy efficiency in various network scenarios. The accuracy of the analysis is verified through Monte-Carlo simulations.

Full-text (2 Sources)

Available from
Nov 24, 2014