Parastoo Sadeghi

Australian National University, Canberra, Australian Capital Territory, Australia

Are you Parastoo Sadeghi?

Claim your profile

Publications (142)112.97 Total impact

  • Source
    Ni Ding, Rodney A. Kennedy, Parastoo Sadeghi
    [Show abstract] [Hide abstract]
    ABSTRACT: We consider the fairness in cooperative data exchange (CDE) problem among a set of wireless clients. In this system, each client initially obtains a subset of the packets. They exchange packets in order to reconstruct the entire packet set. We study the problem of how to find a transmission strategy that distributes the communication load most evenly in all strategies that have the same sum-rate (the total number of transmissions) and achieve universal recovery (the situation when all clients recover the packet set). We formulate this problem by a discrete minimization problem and prove its $M$-convexity. We show that our results can also be proved by the submodularity of the feasible region shown in previous works and are closely related to the resource allocation problems under submodular constraints. To solve this problem, we propose to use a steepest descent algorithm (SDA) based on $M$-convexity. By varying the number of clients and packets, we compare SDA with a deterministic algorithm (DA) based on submodularity in terms of convergence performance and complexity. The results show that for the problem of finding the fairest and minimum sum-rate strategy for the CDE problem SDA is more efficient than DA when the number of clients is up to five.
    02/2015;
  • Source
    Ni Ding, Rodney A. Kennedy, Parastoo Sadeghi
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper considers how to accurately estimate the minimum sum-rate so as to reduce the complexity of solving cooperative data exchange (CDE) problems. The CDE system contains a number of geographically close clients who send packets to help the others recover an entire packet set. The minimum sum-rate is the minimum value of total number of transmissions that achieves universal recovery (the situation when all the clients recover the whole packet set). Based on a necessary and sufficient condition for a supermodular base polyhedron to be nonempty, we show that the minimum sum-rate for a CDE system can be determined by a maximization over all possible partitions of the client set. Due to the high complexity of solving this maximization problem, we propose a deterministic algorithm to approximate a lower bound on the minimum sum-rate. We show by experiments that this lower bound is much tighter than those lower bounds derived in the existing literature. We also show that the deterministic algorithm prevents from repetitively running the existing algorithms for solving CDE problems so that the overall complexity can be reduced accordingly.
    02/2015;
  • Source
    [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;
  • Source
    Mingchao Yu, Parastoo Sadeghi, Neda Aboutorab
    [Show abstract] [Hide abstract]
    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;
  • Source
    [Show abstract] [Hide abstract]
    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
    [Show abstract] [Hide abstract]
    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
  • Shama N. Islam, Parastoo Sadeghi, Salman Durrani
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we propose a novel user pairing scheme to reduce the error propagation in an amplify and forward (AF) based multi-way relay network (MWRN). We consider a user pairing scheme, where, a common user is chosen based on its average channel gain to form pairs with every other user in the MWRN. We show that choosing the common user as the user with the minimum average channel gain reduces the contribution of the interference components from the common user's signal in the extracted signals of other users. This leads to better bit error rate (BER) performance for all other users. For the common user, the BER improves at high SNR but it degrades at low SNR. The results show that the proposed pairing scheme outperforms the existing pairing scheme in terms of average BER of different users at high SNR.
    2014 IEEE Statistical Signal Processing Workshop (SSP); 06/2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper introduces an adaptive, multi-resolution windowing technique that can be used in conjunction with the spatially localized spherical harmonic transform (SLSHT) to process signals on the 2-sphere in the spatio-spectral domain. In contrast with the standard formulation, which uses a fixed window, the new windowing technique is able to respond locally to the signal under analysis, that is, be adaptive, and also is formulated to depend on the spectral degree to give it a multi-resolution character. We further enhance its simultaneous spatial and spectral localization by basing the window on a parametric band-limited Slepian maximum spatial concentration eigenfunction. The criterion for window design is to maximize the energy concentration in each spectral component in the spatio-spectral domain. A computationally efficient method is also developed to implement the adaptive window design. An example is also provided to demonstrate the superiority of the new adaptive, multiresolution window technique.
    2014 IEEE Statistical Signal Processing Workshop (SSP); 06/2014
  • Parastoo Sadeghi, Rodney A. Kennedy, Zubair Khalid
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper we consider the zero-forcing (ZF) and minimum mean square error (MMSE) criteria for signal recovery using linear operators as equalizers for signals observed on the 2-sphere that are subject to linear distortions and noise. The distortions considered are bounded operators and can include convolutions, rotations, spatial and spectral truncations, projections or combinations of these. Likewise the signal and noise are very general being modeled as anisotropic stochastic processes on the 2-sphere. In both the distortion model and signal model the findings in this paper are significantly more general than results that can be found in the literature. The MMSE equalizer is shown to reduce to the ZF equalizer when the distortion operator has an inverse and there is an absence of noise. The ability of the MMSE to recover a Mars topography map signal from a projection operator, which fails to have a ZF solution, is given as an illustration.
    2014 IEEE Statistical Signal Processing Workshop (SSP); 06/2014
  • Rodney A. Kennedy, Zubair Khalid, Parastoo Sadeghi
    [Show abstract] [Hide abstract]
    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
    [Show abstract] [Hide abstract]
    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;
  • Neda Aboutorab, Parastoo Sadeghi, Sameh Sorour
    [Show abstract] [Hide abstract]
    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 04/2014; 62(4):1296-1309. · 1.98 Impact Factor
  • Mohammad S. Karim, Parastoo Sadeghi, Neda Aboutorab
    [Show abstract] [Hide abstract]
    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;
  • Source
    Shama N. Islam, Salman Durrani, Parastoo Sadeghi
    [Show abstract] [Hide abstract]
    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;
  • Source
    [Show abstract] [Hide abstract]
    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;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We consider a group of n wireless clients and a set of k messages. Each client initially holds a subset of messages and is interested in an arbitrary subset of messages. Each client cooperates with other clients to obtain the set of messages it wants by exchanging instantly decodable network coded (IDNC) packets. This problem setting is known as the cooperative index coding problem. Clients are assumed to be connected through an arbitrary topology. In the absence of any known algorithm to complete the exchange of packets for general network topologies, we propose a greedy algorithm to satisfy the demands of all the clients with the aim of reducing the mean completion time. Our algorithm, in a completely distributed fashion, decides which subset of clients should transmit at each round of transmission and which messages should be coded together by each transmitting client to generate an IDNC packet. The algorithm encourages transmissions which are decodable for a larger number of clients and attempts to avoid collisions. We evaluate the performance of our algorithm via numerical experiments.
    2014 Australian Communications Theory Workshop (AusCTW); 02/2014
  • Amy Fu, Parastoo Sadeghi
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we demonstrate a network coded transmission scheme that allows the implementation of multicast video on demand using a single server channel. A receiver is permitted to join the broadcast at any time, where after an initial startup delay, it is able to deliver packets at its channel rate. This transmission scheme is the first to allow in-order packet delivery while providing innovative information to all receivers at all times. We illustrate how this feature can be achieved by taking advantage of the early decoding properties of an existing network coding transmission scheme.
    2014 Australian Communications Theory Workshop (AusCTW); 02/2014
  • Source
    Ni Ding, Parastoo Sadeghi, Rodney A. Kennedy
    [Show abstract] [Hide abstract]
    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;
  • Source
    Amy Fu, Parastoo Sadeghi, Muriel Medard
    [Show abstract] [Hide abstract]
    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;
  • Source
    Neda Aboutorab, Parastoo Sadeghi, Sameh Sorour
    [Show abstract] [Hide abstract]
    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;

Publication Stats

824 Citations
112.97 Total Impact Points

Institutions

  • 2006–2015
    • Australian National University
      • • College of Engineering & Computer Science
      • • Research School of Computer Science
      Canberra, Australian Capital Territory, Australia
  • 2012
    • University of Canberra
      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