I am a Post Doc at WNCG, Univeristy of Texas at Austin in the group of Dr. Jeff Andrews. I received my Ph.D. from University of Notre Dame under the supervision of Dr. Martin Haenggi.
|
|
Research Interests:
Routing and scheduling in Wireless Networks
Information theory
Euclidean geometry (probabilistic)
Fourier Analysis
Nonlinear PDE
Short CV:
Btech: IIT Madras (99-03)
Mtech:IIT Madras (03-04)
Graduate Studies: Notre Dame (04-09)
PhD studies in Electrical Engg.
and Masters in Applied Mathematics
|
|
[4]
|
Spatial Analysis of Opportunistic Downlink Relaying in a Two-Hop Cellular System PDF : Submitted to IEEE Trans. Communications
Abstract: We consider a two-hop cellular system in which the mobile nodes help the base station by relaying information to the dead spots. While two-hop cellular schemes have been analyzed previously, the distribution of the node locations has not been explicitly taken into account. In this paper, we model the node locations of the base stations and the mobile stations as a point process on the plane and then analyze the performance of two different two-hop schemes in the downlink. In one scheme the node nearest to the destination that has decoded information from the base station in the first hop is used as the relay. In the second scheme the node with the best channel to the relay that received information in the first hop acts as a relay. In both these schemes we obtain the success probability of the two hop scheme, accounting for the interference from all other cells. We use tools from stochastic geometry and point process theory to analyze the two hop schemes.
|
|
[3]
|
Spatial and Temporal Correlation of the Interference in ALOHA Ad Hoc Networks PDF : IEEE Communication Letters, Sep. 2009.
Abstract: Interference is a main limiting factor of the performance of a wireless ad hoc network. The temporal and the spatial correlation of the interference makes the outages correlated temporally (important for retransmissions) and spatially correlated (important for routing). In this letter we quantify the temporal and spatial correlation of the interference in a wireless ad hoc network whose nodes are distributed as a Poisson point process on the plane when ALOHA is used as the multiple-access scheme.
|
|
[2]
|
Limit of the Transport Capacity of a Dense Wireless Networks PDF : Submitted to Journal of applied probability.
Abstract: It is known that the transport capacity of a dense wireless ad hoc network with n nodes scales like \sqrt{n}. We show that the transport capacity divided by n approaches a non-random limit with probability one when the nodes are i.i.d uniformly distributed on the unit square. To show the existence of the limit we prove that the transport capacity under the protocol model is a subadditive Euclidean functional and use the machinery of subadditive functions in the spirit of Steele.
|
|
[1] |
Interference and Outage in Clustered Wireless Ad Hoc Networks PDF : IEEE Transactions on Information Theory, Sep. 2009.
Abstract: In the analysis of large random wireless networks, the underlying node distribution is almost ubiquitously assumed to be the homogeneous Poisson point process. In this paper, the node locations are assumed to form a Poisson clustered process on the plane. We derive the distributional properties of the interference and provide upper and lower bounds for its CCDF. We consider the probability of successful transmission in an interference limited channel when fading is modeled as Rayleigh.
|
Technical Reports
[1] Point Mapping Energy: PDF In this report, we study the problem of regularization energy . The problem deals with the average distance that all the points move in a minimum mapping. This problem has close resemblance with the problems of stochastic matching in the discrete domain and the problem of Monge Kantorovich mass transportation. In sensor networks, the locations of the sensor nodes are generally modeled as a point process on a plane or on a line. Usually the sensors are not placed in a perfect grid (lattice) due to physical constraints. Sensor networks with randomly placed nodes suffer from severe disadvantages in terms of connectivity, coverage, and efficiency of communication compared with networks with a regular topology. It is of interest to understand the properties of the minimum energy required to move the sensor nodes to unique points of the grid. Another question that arises is how regularly the points of the underlying process are arranged. Thus the regularization energy may be used to assess the regularity of a point process. More importantly this is a elegant problem to understand the dynamics in random Euclidean matching problems.
Conference Publications
| [11]
|
Radha Krishna Ganti and M. Haenggi, "Bounds on Information Propagation Delay in Interference-Limited ALOHA Networks
" SPASWIN-2009 PDF
|
| [10]
|
Radha Krishna Ganti and M. Haenggi, "Analysis of Uncoordinated Opportunistic Two-Hop Wireless Ad Hoc Systems
" ISIT-2009 PDF
Abstract: We consider a time-slotted two-hop wireless system in which the sources transmit to the relays in the even time slots (first hop) and the relays forward the packets to the destinations in the odd time slots (second hop). Each source may connect to multiple relays in the first hop. In the presence of interference and without tight coordination of the relays, it is not clear which relays should transmit the packet. We propose four decentralized methods of relay selection, some based on location information and others based on the received signal strength (RSS). We provide a complete analytical characterization of these methods using tools from stochastic geometry. We use simulation results to compare these methods in terms of end-to-end success probability.
|
| [9]
|
Radha Krishna Ganti and M. Haenggi, "Throughput Versus Routing Overhead in Large Ad Hoc
Networks
" The Fourth International Wireless Internet Conference (WICON 2008) PDF
Abstract: Consider a wireless ad hoc network with n nodes distributed uniformly on [0, 1]^2 . The transport capacity (TC) of such
wireless network scales like \sqrt{n}. To achieve this, each node should serve about \sqrt{n} distinct information flows. So the routing table of each node should be of the order \sqrt{n} bits. We show that if the size of the routing table is restricted to be of the order O(n^H(δ) ), the maximum achievable per-node TC is O(n^R(δ) ) when the source-destination distance ¯is n^{−δ/2}. We show that R(δ) = min {1/2 ,\delta/2+ H(δ)} − 1 is the optimal tradeoff.
|
| [8]
|
Radha Krishna Ganti and M. Haenggi, "The Transport Capacity of a Wireless Network is a Subadditive Euclidean
Functional" First IEEE Workshop on the Theory of Ad-Hoc and Sensor Networks (ThASN '08) PDF
Abstract: The transport capacity of a dense ad hoc network with n nodes scales
like \sqrt(n). We show that the transport capacity divided by \sqrt(n)
approaches a non-random limit with
probability one when the nodes are i.i.d. distributed on the
unit square. We prove that the transport capacity under the
protocol model is a subadditive Euclidean functional and
use the machinery of subadditive functions in the spirit of
Steele to show the existence of the limit.
|
|
[7]
|
Steven Weber, Nihar Jindal, Radha krishna Ganti and Martin Haenggi, "Longest edge routing on the spatial Aloha graph" Globecom-2008 PDF
Abstract: The multihop spatial reuse Aloha (MSR-Aloha)
protocol was recently introduced by Baccelli et al., where each
transmitter selects the receiver among its feasible next hops
that maximizes the forward progress of the head of line packet
towards its final destination. They identify the optimal medium
access probability (MAP) that maximizes the spatial density
of progress, defined as the product of the spatial intensity of
attempted transmissions times the average per-hop progress of
each packet towards its destination. We propose a variant called
longest edge routing where each transmitter selects its longest
feasible edge, and then identifies a packet in its backlog whose
next hop is the associated receiver. The main contribution of this
work (and of Baccelli et al.) is the use of stochastic geometry to
identify the optimal MAP and the corresponding optimal spatial
|
|
[6]
|
Radha Krishna Ganti and M. Haenggi, "Interference in Ad Hoc Networks with Genera
Motion-Invariant Node Distributions" ISIT-2008 PDF
Abstract: In this paper we derive the tail properties of interference for any stationary and isotropic spatial distribution of
transmitting nodes. Previously the properties of interference were
known only when the nodes are distributed as a homogeneous
Poisson point process on the plane. We show the effect of
a singular path loss model on the tail distribution of the
interference. When the path loss function has a singularity at the
origin, the interference is shown to be a heavy-tailed distribution
under very mild conditions. When the path loss is bounded,
the distribution of the interference is predominantly dictated
by the fading. We also provide asymptotically tight upper and
lower bounds on the CDF of the interference, and discuss the
effectiveness of using a Gaussian approximation for modelling
the interference.
|
|
[5]
|
Radha Krishna Ganti and M. Haenggi, `Dynamic Connectivity and Packet Propagation Delay in ALOHA Wireless Networks'' 41st Asilomar Conference on Signals, Systems, and Computers (Asilomar'07), (Pacific Grove, CA) , Nov. 2007. PDF
Abstract: We consider an ad hoc network which uses multihop and
slotted ALOHA for its MAC contention. We then formulate the minimum
time required for a packet to reach the destination from the origin. We
define this delay as the minimum time required for a causal path to
form between the source and destination. We derive the distributional
properties of the connection time using ideas from first passage
percolation and epidemic processes. We show that the delay scales
linearly with the distance and also provide asymptotic results (w.r.t
time) for the positions of the nodes which are able to connect to a
transmitter located at the origin. We also provide simulation results
to support the theoretical results.
|
|
[4]
|
Radha Krishna Ganti and M. Haenggi, `Single-Hop Connectivity in Interference Limited
Hybrid Wireless Networks'' in 2007 IEEE International Symposium on Information Theory (ISIT'07), (Nice, France), June 2007 PDF && slides
Abstract: We calculate the single hop connectivity in a Ad-Hoc hybrid wireless
network. We consider a Poisson arrangement of communicating sensor
nodes and base stations. We give analytical expressions for the
probability of a sensor node not being able to connect to any base
station (isolation probability) when the base stations are randomly or
regularly arranged.
|
|
[3]
|
Radha Krishna Ganti and M. Haenggi, `Regularity, Interference, and Capacity of Large Ad Hoc Networks'' 40th Asilomar Conference on Signals, Systems, and Computers (Asilomar'06), (Pacific Grove, CA) , Oct. 2006. PDF
Abstract: Outage probability is evaluated when the sensor/adhoc nodes form a
clustered process and the fading is Rayleigh. The transmission capacity
of this process is also evaluated.
|
|
[2]
|
Radha Krishna Ganti and M. Haenggi, `Regularization Energy '' Second Workshop on Spatial Stochastic Models for Wireless Networks , April 2006. PDF && slides
Abstract: Regularization energy is defined as the energy required to move the
points of a homogeneous point process in a bounded set to unique points
of a lattice. The optimal mapping required for this movement is derived
for one dimensional processes, and bounds are derived for the Poisson
point process in one and two dimensions. In addition regularization
energy is evaluated for well known point processes in one dimension by
simulation.
|
|
[1]
|
Radha Krishna Ganti and M. Haenggi, `Regularity in Sensor Networks '' International Zurich Seminar on Communications, Feb 2006. PDF && slides
Abstract: We motivate the need for a metric to characterize the regularity of
node placement in sensor networks. Practical metrics are proposed and
evaluated for different stationary point process models. |
|
|
