Parastoo Sadeghi

Australian National University, Canberra, Australian Capital Territory, Australia

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Publications (135)99.37 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper studies the problem of broadcasting layered video streams over heterogeneous single-hop wireless networks using feedback-free random linear network coding (RLNC). We combine RLNC with unequal error protection (UEP) and our main purpose is twofold. First, to systematically investigate the benefits of UEP+RLNC layered approach in servicing users with different reception capabilities. Second, to study the effect of not using feedback, by comparing feedback-free schemes with idealistic full-feedback schemes. To these ends, we study `expected percentage of decoded frames' as a key content-independent performance metric and propose a general framework for calculation of this metric, which can highlight the effect of key system, video and channel parameters. We study the effect of number of layers and propose a scheme that selects the optimum number of layers adaptively to achieve the highest performance. Assessing the proposed schemes with real H.264 test streams, the trade-offs among the users' performances are discussed and the gain of adaptive selection of number of layers to improve the trade-offs is shown. Furthermore, it is observed that the performance gap between the proposed feedback-free scheme and the idealistic scheme is very small and the adaptive selection of number of video layers further closes the gap.
    11/2014;
  • Mingchao Yu, Parastoo Sadeghi, Neda Aboutorab
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    ABSTRACT: Deterministic linear network coding (DLNC) is an important family of network coding techniques for wireless packet broadcast. In this paper, we show that DLNC is strongly related to and can be effectively studied using matroid theory without bridging index coding. We prove the equivalence between the DLNC solution and matrix matroid. We use this equivalence to study the performance limits of DLNC in terms of the number of transmissions and its dependence on the finite field size. Specifically, we derive the sufficient and necessary condition for the existence of perfect DLNC solutions and prove that such solutions may not exist over certain finite fields. We then show that identifying perfect solutions over any finite field is still an open problem in general. To fill this gap, we develop a heuristic algorithm which employs graphic matroids to find perfect DLNC solutions over any finite field. Numerical results show that its performance in terms of minimum number of transmissions is close to the lower bound, and is better than random linear network coding when the field size is not so large.
    06/2014;
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    ABSTRACT: Coding techniques may be useful for data center data survivability as well as for reducing traffic congestion. We present a queued cross-bar network (QCN) method that can be used for traffic analysis of both replication/uncoded and coded storage systems. We develop a framework for generating QCN rate regions (RRs) by analyzing their conflict graph stable set polytopes (SSPs). In doing so, we apply recent results from graph theory on the characterization of particular graph SSPs. We characterize the SSP of QCN conflict graphs under a variety of traffic patterns, allowing for their efficient RR computation. For uncoded systems, we show how to compute RRs and find rate optimal scheduling algorithms. For coded storage, we develop a RR upper bound, for which we provide an intuitive interpretation. We show that the coded storage RR upper bound is achievable in certain coded systems in which drives store sufficient coded information, as well in certain dynamic coding systems. Numerical illustrations show that coded storage can result in gains in RR volume of approximately 50%, averaged across traffic patterns.
    06/2014;
  • Amy Fu, Parastoo Sadeghi
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    ABSTRACT: In random linear network coding, rate control is an important strategy for limiting the decoding delay of a system. In broadcast systems where the channel rate is either unknown or varies over time, we demonstrate that a target delay can be achieved using the queue threshold scheme that we introduce. At throughputs approaching the channel rate, the queue threshold rate control scheme is shown to achieve improved throughput delay performance compared with existing schemes. We demonstrate that it is possible to modify this rate control scheme to greatly reduce the amount of feedback required, in exchange for a slight degradation of the throughput delay performance. Furthermore, this rate control scheme is shown to perform reasonably well, even under lossy and delayed feedback.
    ICC 2014 - 2014 IEEE International Conference on Communications; 06/2014
  • Rodney A. Kennedy, Zubair Khalid, Parastoo Sadeghi
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    ABSTRACT: In this paper we show that the spatially localized spherical harmonic transform (SLSHT), which represents a signal on the 2-sphere in the spatio-spectral domain, can be efficiently computed using new kernel-based formulations. In addition to the standard spatio-spectral domain, we show there are three other related transforms that provide alternative representations in the spatio-spatial, spectro-spatial and spectro-spectral domains. We provide inversion results that extend available results for the SLSHT. We show that for signals on the 2-sphere band-limited to degree L, the computational complexity using our class of kernel-based SLSHT transforms is O(L4) and outperforms the previous best known fast methods, which have complexity O(L5).
    ICASSP 2014 - 2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP); 05/2014
  • Source
    Mohammad S. Karim, Parastoo Sadeghi, Neda Aboutorab
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    ABSTRACT: In this paper, we study in-order packet delivery in instantly decodable network coded systems for wireless broadcast networks.We are interested in particular applications, in which the successful delivery of a packet depends on the correct reception of this packet and all its preceding packets. We formulate the problem of minimizing the number of undelivered packets to all receivers over all transmissions until completion as a stochastic shortest path (SSP) problem. Although finding the optimal packet selection policy using SSP is computationally intractable, we employ this formulation to draw guidelines for the packet selection policies that can efficiently reduce the number of undelivered packets to all receivers over all transmissions until completion. According to these guidelines, we design a simple heuristic packet selection algorithm. In addition, we extend this heuristic to erasure channels with memory and introduce another layered algorithm. Simulation results illustrate that our proposed algorithms provide quicker delivery of the packets to the receivers compared to the existing algorithms in the literature.
    04/2014;
  • Mohammad S. Karim, Parastoo Sadeghi, Neda Aboutorab
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    ABSTRACT: In this paper, we study in-order packet delivery in instantly decodable network coded systems for wireless broadcast networks.We are interested in particular applications, in which the successful delivery of a packet depends on the correct reception of this packet and all its preceding packets. We formulate the problem of minimizing the number of undelivered packets to all receivers over all transmissions until completion as a stochastic shortest path (SSP) problem. Although finding the optimal packet selection policy using SSP is computationally intractable, we employ this formulation to draw guidelines for the packet selection policies that can efficiently reduce the number of undelivered packets to all receivers over all transmissions until completion. According to these guidelines, we design a simple heuristic packet selection algorithm. In addition, we extend this heuristic to erasure channels with memory and introduce another layered algorithm. Simulation results illustrate that our proposed algorithms provide quicker delivery of the packets to the receivers compared to the existing algorithms in the literature.
    03/2014;
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    Shama N. Islam, Salman Durrani, Parastoo Sadeghi
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    ABSTRACT: In this paper, we consider a functional decode and forward (FDF) multi-way relay network (MWRN) where a common user facilitates each user in the network to obtain messages from all other users. We propose a novel user pairing scheme, which is based on the principle of selecting a common user with the best average channel gain. This allows the user with the best channel conditions to contribute to the overall system performance. Assuming lattice code based transmissions, we derive upper bounds on the average common rate capacity and the average sum rate with the proposed pairing scheme. Considering binary phase shift keying modulation as the simplest case of lattice code transmission, we derive asymptotic average bit error rate (BER) of the MWRN. We show that in terms of the achievable rates, the proposed pairing scheme outperforms the existing pairing schemes under a wide range of channel scenarios. The proposed pairing scheme also has lower average BER compared to existing schemes. We show that overall, the MWRN performance with the proposed pairing scheme is more robust, compared to existing pairing schemes, especially under worst case channel conditions when majority of users have poor average channel gains.
    02/2014;
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    ABSTRACT: We consider scheduling strategies for point-to-multipoint (PMP) storage area networks (SANs) that use network coded storage (NCS). In particular, we present a simple SAN system model, two server scheduling algorithms for PMP networks, and analytical expressions for internal and external blocking probability. We point to select scheduling advantages in NCS systems under normal operating conditions, where content requests can be temporarily denied owing to finite system capacity from drive I/O access or storage redundancy limitations. NCS can lead to improvements in throughput and blocking probability due to increased immediate scheduling options, and complements other well documented NCS advantages such as regeneration, and can be used as a guide for future storage system design.
    02/2014;
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    Ni Ding, Parastoo Sadeghi, Rodney A. Kennedy
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    ABSTRACT: This paper proposes the use of discrete stochastic approximation (DSA) algorithm for a cross-layer adaptive modulation problem in wireless communications. In this system, the throughput in the physical (PHY) layer and quality of service (QoS) incurred by the queueing effects in the data link layer are required to be optimized simultaneously and in the long run. By assuming Markov decision process (MDP) modeling, we prove that the optimal transmission policy is characterized by a queue threshold vector and can be determined by a multivariate discrete convex optimization problem if the dynamic programming (DP) is submodular. We then propose to use DSA, a subgradient-based stochastic approximation (SA) algorithm with proven convergence rate, for approximating the optimal value of the queue threshold vector. By an application in a cross-layer transmission control problem in a network-coded two way relay channel (NC-TWRC), we compare the performance of DSA with that of simultaneous perturbation stochastic approximation (SPSA), the commonly used SA algorithm for threshold policy optimization problems. The results show that DSA converges faster than SPSA resulting in lower and controllable computational cost.
    01/2014;
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    Amy Fu, Parastoo Sadeghi, Muriel Medard
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    ABSTRACT: In a single hop broadcast packet erasure network, we demonstrate that it is possible to provide multirate packet delivery outside of what is given by the network min-cut. This is achieved by using a deterministic non-block-based network coding scheme, which allows us to sidestep some of the limitations put in place by the block coding model used to determine the network capacity. Under the network coding scheme we outline, the sender is able to transmit network coded packets above the channel rate of some receivers, while ensuring that they still experience nonzero delivery rates. Interestingly, in this generalised form of asynchronous network coded broadcast, receivers are not required to obtain knowledge of all packets transmitted so far. Instead, causal feedback from the receivers about packet erasures is used by the sender to determine a network coded transmission that will allow at least one, but often multiple receivers, to deliver their next needed packet. Although the analysis of deterministic coding schemes is generally a difficult problem, by making some approximations we are able to obtain tractable estimates of the receivers' delivery rates, which are shown to match reasonably well with simulation. Using these estimates, we design a fairness algorithm that allocates the sender's resources so all receivers will experience fair delivery rate performance.
    01/2014;
  • Neda Aboutorab, Parastoo Sadeghi, Sameh Sorour
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    ABSTRACT: This paper studies the complicated interplay of the completion time (as a measure of throughput) and the decoding delay performance in instantly decodable network coded (IDNC) systems over wireless broadcast erasure channels with memory. We propose two new algorithms that enable a tradeoff for an improved balance between completion time and decoding delay of broadcasting a block of packets. We first formulate the IDNC packet selection problem that improves the balance between completion time and decoding delay as a statistical shortest path (SSP) problem. However, since finding such packet selection policy using the SSP technique is computationally complex, we employ its geometric structure to find some guidelines and use them to propose two efficient heuristic packet selection algorithms for broadcast erasure channels with a wide range of memory conditions. It is shown that each one of the two proposed algorithms is superior for a specific range of memory conditions. Furthermore, we show that the proposed algorithms achieve an improved fairness in terms of the decoding delay across all receivers.
    IEEE Transactions on Communications 01/2014; 62(4):1296-1309. · 1.75 Impact Factor
  • Source
    Neda Aboutorab, Parastoo Sadeghi, Sameh Sorour
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    ABSTRACT: This paper studies the complicated interplay of the completion time (as a measure of throughput) and the decoding delay performance in instantly decodable network coded (IDNC) systems over wireless broadcast erasure channels with memory, and proposes two new algorithms that improve the balance between the completion time and decoding delay of broadcasting a block of packets. We first formulate the IDNC packet selection problem that provides joint control of the completion time and decoding delay as a statistical shortest path (SSP) problem. However, since finding the optimal packet selection policy using the SSP technique is computationally complex, we employ its geometric structure to find some guidelines and use them to propose two heuristic packet selection algorithms that can efficiently improve the balance between the completion time and decoding delay for broadcast erasure channels with a wide range of memory conditions. It is shown that each one of the two proposed algorithms is superior for a specific range of memory conditions. Furthermore, we show that the proposed algorithms achieve an improved fairness in terms of the decoding delay across all receivers.
    11/2013;
  • Source
    Ni Ding, Parastoo Sadeghi, Rodney A. Kennedy
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    ABSTRACT: This paper considers a transmission control problem in network-coded two-way relay channels (NC-TWRC), where the relay buffers random symbol arrivals from two users, and the channels are assumed to be fading. The problem is modeled by a discounted infinite horizon Markov decision process (MDP). The objective is to find a transmission control policy that minimizes the symbol delay, buffer overflow and transmission power consumption and error rate simultaneously and in the long run. By using the concepts of submodularity, multimodularity and L-natural convexity, we study the structure of the optimal policy searched by dynamic programming (DP) algorithm. We show that the optimal transmission policy is nondecreasing in queue occupancies or/and channel states under certain conditions such as the chosen values of parameters in the MDP model, channel modeling method, modulation scheme and the preservation of stochastic dominance in the transitions of system states. The results derived in this paper can be used to relieve the high complexity of DP and facilitate real-time control.
    10/2013;
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    Shama Naz Islam, Salman Durrani, Parastoo sadeghi
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    ABSTRACT: In this study, we analyse the error performance of decode and forward (DF) and amplify and forward (AF) multi-way relay networks (MWRNs). The authors consider a MWRN with pair-wise data exchange protocol using binary phase shift keying (BPSK) modulation in both additive white Gaussian noise (AWGN) and Rayleigh fading channels. The authors quantify the possible error events in an L-user DF or AF MWRN and derive accurate asymptotic bounds on the probability for the general case that a user incorrectly decodes the messages of exactly k (k ∈ [1, L − 1]) users. They show that at high signal-to-noise ratio (SNR), the higher order error events (k ≥ 3) are less probable in AF MWRN, but all error events are equally probable in a DF MWRN. They derive the average BER of a user in a DF or AF MWRN in both AWGN and Rayleigh fading channels under high SNR conditions. Simulation results validate the correctness of the derived expressions. The authors results show that at medium to high SNR, DF MWRN provides better error performance than AF MWRN in AWGN channels even with a large number of users (e.g. L = 100). Whereas, AF MWRN outperforms DF MWRN in Rayleigh fading channels even for much smaller number of users (e.g. L > 10).
    IET Communications 10/2013; 7(15):1605-1616. · 0.72 Impact Factor
  • Mingchao Yu, Neda Aboutorab, Parastoo Sadeghi
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    ABSTRACT: Our primary goal in this paper is to traverse the performance gap between two linear network coding schemes: random linear network coding (RLNC) and instantly decodable network coding (IDNC) in terms of throughput and decoding delay. We first redefine the concept of packet generation and use it to partition a block of partially-received data packets in a novel way, based on the coding sets in an IDNC solution. By varying the generation size, we obtain a general coding framework which consists of a series of coding schemes, with RLNC and IDNC identified as two extreme cases. We then prove that the throughput and decoding delay performance of all coding schemes in this coding framework are bounded between the performance of RLNC and IDNC and hence throughput-delay tradeoff becomes possible. We also propose implementations of this coding framework to further improve its throughput and decoding delay performance, to manage feedback frequency and coding complexity, or to achieve in-block performance adaption. Extensive simulations are then provided to verify the performance of the proposed coding schemes and their implementations.
    09/2013;
  • Mingchao Yu, Parastoo Sadeghi, Neda Aboutorab
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    ABSTRACT: In this paper, a comprehensive study of packet-based instantly decodable network coding (IDNC) for single-hop wireless broadcast is presented. The optimal IDNC solution in terms of throughput is proposed and its packet decoding delay performance is investigated. Lower and upper bounds on the achievable throughput and decoding delay performance of IDNC are derived and assessed through extensive simulations. Furthermore, the impact of receivers' feedback frequency on the performance of IDNC is studied and optimal IDNC solutions are proposed for scenarios where receivers' feedback is only available after and IDNC round, composed of several coded transmissions. However, since finding these IDNC optimal solutions is computational complex, we further propose simple yet efficient heuristic IDNC algorithms. The impact of system settings and parameters such as channel erasure probability, feedback frequency, and the number of receivers is also investigated and simple guidelines for practical implementations of IDNC are proposed.
    09/2013;
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    ABSTRACT: In this paper, we present an optimal filter for the enhancement or estimation of signals on the 2-sphere corrupted by noise, when both the signal and noise are realizations of anisotropic processes on the 2-sphere. The estimation of such a signal in the spatial or spectral domain separately can be shown to be inadequate. Therefore, we develop an optimal filter in the joint spatio-spectral domain by using a framework recently presented in the literature --- the spatially localized spherical harmonic transform --- enabling such processing. Filtering of a signal in the spatio-spectral domain facilitates taking into account anisotropic properties of both the signal and noise processes. The proposed spatio-spectral filtering is optimal under the mean-square error criterion. The capability of the proposed filtering framework is demonstrated with by an example to estimate a signal corrupted by an anisotropic noise process.
    Proc SPIE 08/2013;
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    ABSTRACT: This paper considers the construction of Reproducing Kernel Hilbert Spaces (RKHS) on the sphere as an alternative to the conventional Hilbert space using the inner product that yields the L^2(S^2) function space of finite energy signals. In comparison with wavelet representations, which have multi-resolution properties on L^2(S^2), the representations that arise from the RKHS approach, which uses different inner products, have an overall smoothness constraint, which may offer advantages and simplifications in certain contexts. The key contribution of this paper is to construct classes of closed-form kernels, such as one based on the von Mises-Fisher distribution, which permits efficient inner product computation using kernel evaluations. Three classes of RKHS are defined: isotropic kernels and non-isotropic kernels both with spherical harmonic eigenfunctions, and general anisotropic kernels.
    Proc SPIE 08/2013;
  • Source
    Shama N. Islam, Parastoo Sadeghi, Salman Durrani
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we analyze the error performance of decode and forward (DF) and amplify and forward (AF) multi-way relay networks (MWRN). We consider a MWRN with pair-wise data exchange protocol using binary phase shift keying (BPSK) modulation in both additive white Gaussian noise (AWGN) and Rayleigh fading channels. We quantify the possible error events in an $L$-user DF or AF MWRN and derive accurate asymptotic bounds on the probability for the general case that a user incorrectly decodes the messages of exactly $k$ ($k\in[1,L-1]$) users. We show that at high signal-to-noise ratio (SNR), the higher order error events ($k\geq 3$) are less probable in AF MWRN, but all error events are equally probable in a DF MWRN. We derive the average BER of a user in a DF or AF MWRN in both AWGN and Rayleigh fading channels under high SNR conditions. Simulation results validate the correctness of the derived expressions. Our results show that at medium to high SNR, DF MWRN provides better error performance than AF MWRN in AWGN channels even with a large number of users (for example, L=100). Whereas, AF MWRN outperforms DF MWRN in Rayleigh fading channels even for much smaller number of users (for example, $L > 10$).
    08/2013;

Publication Stats

565 Citations
99.37 Total Impact Points

Institutions

  • 2006–2013
    • Australian National University
      • • Research School of Computer Science
      • • Research School of Engineering
      • • College of Engineering & Computer Science
      Canberra, Australian Capital Territory, Australia
  • 2009–2011
    • Sharif University of Technology
      • Department of Electrical Engineering
      Tehrān, Ostan-e Tehran, Iran
  • 2010
    • Texas A&M University
      • Department of Electrical and Computer Engineering
      College Station, Texas, United States
  • 2003–2005
    • University of New South Wales
      • School of Electrical Engineering and Telecommunications
      Kensington, New South Wales, Australia