Zubin Bharucha - Academia.edu (original) (raw)

Papers by Zubin Bharucha

Research Letters in Communications, 2008

When simulating a wireless network, users/nodes are usually assumed to be distributed uniformly i... more When simulating a wireless network, users/nodes are usually assumed to be distributed uniformly in space. Path losses between nodes in a simulated network are generally calculated by determining the distance between every pair of nodes and applying a suitable path loss model as a function of this distance (power of distance with an environment-specific path loss exponent) and adding a random component to represent the log-normal shadowing. A network with N nodes consists of N(N − 1)/2 path loss values. In order to generate statistically significant results for system-level simulations, Monte Carlo simulations must be performed where the nodes are randomly distributed at the start of every run. This is a time-consuming operation which need not be carried out if the distribution of path losses between the nodes is known. The probability density function (pdf) of the path loss between the centre of a circle and a node distributed uniformly within a the circle is derived in this work.

EURASIP Journal on Wireless Communications and Networking, 2012

One of the key challenges for future orthogonal frequency division multiple access-based networks... more One of the key challenges for future orthogonal frequency division multiple access-based networks is inter-cell interference coordination. With full frequency reuse and small inter-site distances, coping with co-channel interference (CCI) in such networks has become increasingly important. In this article, an uplink interference protection (ULIP) technique to combat CCI is introduced and investigated. The level of uplink interference originating from neighbouring cells (affecting co-channel mobile stations (MSs) in the cell of interest) can be effectively controlled by reducing the transmit power of the interfering MSs. This is done based on the target signal-to-noise-plus-interference ratio (SINR) and tolerable interference of the vulnerable link. Bands are prioritised in order to differentiate those (vulnerable/victim) MSs that are to be protected from interference and those (aggressor/interfering MSs) that are required to sacrifice transmission power to facilitate the protection. Furthermore, MSs are scheduled such that those users with poorer transmission conditions receive the highest interference protection, thus balancing the areal SINR distribution and creating a fairer allocation of the available resources. In addition to interference protection, the individual power reductions also serve to decrease the total system uplink power, resulting in a greener system. It is shown through analytic derivation that the introduction of ULIP guarantees an increase in energy efficiency for all MSs, with the added benefit that gains in overall system throughput are also achievable. Extensive system level simulations validate these findings.

2012 Conference Record of the Forty Sixth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 2012

ABSTRACT A distributed and autonomous technique for resource and power allocation in femto-cell n... more ABSTRACT A distributed and autonomous technique for resource and power allocation in femto-cell networks is presented. Resource blocks (RBs) are assigned to the user(s) in each cell individually without coordination between base stations (BSs). The allocatability of each resource is determined using only local information: · the user's required rate; · the quality of the desired signal; · the level of interference incident on each RB; and · the frequency-selective fading on each RB. Using fuzzy logic, these inputs are combined to determine which RBs are most suitable for allocation in a particular cell. A comprehensive study of this system yields a staggering system performance improvement over state-of-the-art interference coordination techniques.

2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC), 2012

2012 IEEE Vehicular Technology Conference (VTC Fall), 2012

2011 8th International Workshop on Multi-Carrier Systems & Solutions, 2011

In this paper a new method for uplink intercell interference coordination (ICIC) in a full freque... more In this paper a new method for uplink intercell interference coordination (ICIC) in a full frequency reuse system is proposed. The technique is named uplink interference protection (ULIP). ULIP exploits existing reference signals transmitted by all base stations (BSs). The fact that path loss and lognormal shadowing can be considered reciprocal in such frequency-division duplex (FDD) systems is exploited. Therefore, no additional signalling is required for a new mobile station (MS) to estimate the level of inter-cell interference it would cause to ongoing uplink transmissions in neighbouring cells. Using the acquired knowledge, MSs can adjust their transmit power to ensure that existing links are not forced into outage. A scheduling scheme is suggested in which a fair allocation of priority resource blocks (RBs), based on user signal-tointerference-plus-noise ratios (SINRs), enhances both cell-edge throughput and user throughput fairness. Through this, also significant system throughput gains are generated. Finally, it is demonstrated that as a side effect of the interference reductions, considerable energy savings can be achieved.

2011 IEEE GLOBECOM Workshops (GC Wkshps), 2011

A distributed and dynamic resource reuse method applicable to randomly deployed, possibly dense w... more A distributed and dynamic resource reuse method applicable to randomly deployed, possibly dense wireless networks is presented in this paper. The main objective is to protect mobile users located near the cell boundary from detrimental downlink interference originating from neighboring base stations (BSs) without compromising the system spectral efficiency. For this purpose, a novel autonomous resource assignment method that is

2011 IEEE 73rd Vehicular Technology Conference (VTC Spring), 2011

We address interference avoidance by resource par- titioning in densely deployed femtocell networ... more We address interference avoidance by resource par- titioning in densely deployed femtocell networks. The main objective is to protect user equipments (UEs) that are located near the cell boundary of two or more femtocells from detrimental downlink interference. The available frequency bands are divided into subbands that are distributed among femtocells in a way that directly adjacent cells do not

2011 IEEE Vehicular Technology Conference (VTC Fall), 2011

With considerable interest being garnered in recent years, femto-cells are seen as a major conten... more With considerable interest being garnered in recent years, femto-cells are seen as a major contender to significantly increase capacity and fill coverage holes in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) cellular networks. User- deployed femto-cells, each exclusively serving a set of registered users and sharing the same frequency spectrum as the overlay macro-cells are already defined in

2011 IEEE Wireless Communications and Networking Conference, 2011

... 4, pp. 469477, Mar. 31 2010, (invited). [9] H. Mahmoud, I. Güandvenç ... 2001. [20] K. Bruen... more ... 4, pp. 469477, Mar. 31 2010, (invited). [9] H. Mahmoud, I. Güandvenç ... 2001. [20] K. Brueninghaus, D. Astély, T. Sälzer, S. Visuri, A. Alexiou, S. Karger, and G.-A. Seraji, Link Performance Models for System Level Sim-ulations of Broadband Radio Access Systems, in Proc. ...

EURASIP Journal on Wireless Communications and Networking, 2010

Femto-cells consist of user-deployed Home Evolved NodeBs (HeNBs) that promise substantial gains i... more Femto-cells consist of user-deployed Home Evolved NodeBs (HeNBs) that promise substantial gains in system spectral efficiency, coverage, and data rates due to an enhanced reuse of radio resources. However, reusing radio resources in an uncoordinated, random fashion introduces potentially destructive interference to the system, both, in the femto and macro layers. An especially critical scenario is a closed-access femto-cell, cochannel deployed with a macro-cell, which imposes strong downlink interference to nearby macro user equipments (UEs) that are not permitted to hand over to the femto-cell. In order to maintain reliable service of macro-cells, it is imperative to mitigate the destructive femto-cell to macro-cell interference. The contribution in this paper focuses on mitigating downlink femto-cell to macro-cell interference through dynamic resource partitioning, in the way that HeNBs are denied access to downlink resources that are assigned to macro UEs in their vicinity. By doing so, interference to the most vulnerable macro UEs is effectively controlled at the expense of a modest degradation in femto-cell capacity. The necessary signaling is conveyed through downlink high interference indicator (DL-HII) messages over the wired backbone. Extensive system level simulations demonstrate that by using resource partitioning, for a sacrifice of 4% of overall femto downlink capacity, macro UEs exposed to high HeNB interference experience a tenfold boost in capacity.

Deployment, PHY Techniques, and Resource Management, 2009

VTC Spring 2008 - IEEE Vehicular Technology Conference, 2008

This paper presents a spectrum sharing approach which exploits the clustered distribution of user... more This paper presents a spectrum sharing approach which exploits the clustered distribution of users as would be expected in a typical home with several communicating devices (also known as a femto-cell) or in public places such as airports, malls, etc. From each cluster, a mobile station (MS), known as a gateway mobile (GM), acts as a relay between the other

2012 IEEE Wireless Communications and Networking Conference (WCNC), 2012

We consider in this paper downlink scheduling at the Medium Access Layer (MAC) layer for delay se... more We consider in this paper downlink scheduling at the Medium Access Layer (MAC) layer for delay sensitive traffic in wireless systems based on Orthogonal Frequency Division Multiple Access (OFDMA). We refer in particular to next generation wireless systems such as 3GPP-LTE. We propose an Opportunistic Packet Loss Fair (OPLF) scheduling algorithm based on calculating a simple dynamic priority function which

2012 IEEE 13th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2012

2009 IEEE Globecom Workshops, 2009

This paper studies the impact of femto-cell underlay deployment that share radio frequency resour... more This paper studies the impact of femto-cell underlay deployment that share radio frequency resources with urban macro-cells. Femto-cells promise substantial gains in spectral efficiency due to an enhanced reuse of radio resources. However, owing to their random and uncoordinated deployment, femtocells potentially cause destructive interference to macro-cells and vice versa. In order to maintain reliable service of macro-cells, it is most important to mitigate destructive femto to macro-cell interference. In the downlink, this can be achieved by dynamic resource partitioning, in the way that femto base stations (BS) are denied access to resources that are assigned to close by macro mobile stations (MS). By doing so, interference to the macro-cells is effectively controlled, at the expense of a modest degradation in femto-cell capacity. The necessary signalling is conveyed through the wired backbone, using a high interference indicator (HII).