Karachi, Pakistan
Karachi, Pakistan

United Mobile is the largest mobile distributor in Pakistan with 32 customer care centres in 14 major cities of Pakistan.Founded in the 2001, they earned the ISO 90001 certification in 2005. United Mobile was the Official dealer of Nokia in Pakistan till the year 2013, celebrating their 10 Years of Association with Nokia.Voice Mobile is a mobile brand of United Mobile in Pakistan which was launched in September 2013. Voice operates in Pakistan through United Mobile’s franchises and their authorized dealers, wholesalers and retailers. Wikipedia.


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Zhu H.,University of Minnesota | Prasad N.,United Mobile | Rangarajan S.,United Mobile
IEEE Transactions on Signal Processing | Year: 2012

This paper studies the instantaneous rate maximization and the weighted sum delay minimization problems over a $K$-user multicast channel, where multiple antennas are available at the transmitter as well as at all the receivers. Motivated by the degree of freedom optimality and the simplicity offered by linear precoding schemes, we consider the design of linear precoders using the aforementioned two criteria. We first consider the scenario wherein the linear precoder can be any complex-valued matrix subject to rank and power constraints. We propose cyclic alternating ascent based precoder design algorithms and establish their convergence to respective stationary points. Simulation results reveal that our proposed algorithms considerably outperform known competing solutions. We then consider a scenario in which the linear precoder can be formed by selecting and concatenating precoders from a given finite codebook of precoding matrices, subject to rank and power constraints. We show that under this scenario, the instantaneous rate maximization problem is equivalent to a robust submodular maximization problem which is strongly NP hard. We propose a deterministic approximation algorithm and show that it yields a bicriteria approximation. For the weighted sum delay minimization problem we propose a simple deterministic greedy algorithm, which at each step entails approximately maximizing a submodular set function subject to multiple knapsack constraints, and establish its performance guarantee. © 2012 IEEE.


Sundaresan K.,United Mobile | Sivakumar R.,Georgia Institute of Technology
IEEE Transactions on Mobile Computing | Year: 2011

The use of smart antennas in multihop wireless networks has garnered significant attention over the last few years. Given the unique capabilities of smart antennas, and how they can improve performance in a typically constrained multihop wireless network (MWN) environment, the attention is with merit. However, not much light has been shed on MWNs that have nodes with varying antenna capabilities. While homogeneous MWNs with all nodes having the same antenna capabilities will have certain applications, we argue that MWNs with nodes having heterogeneous antenna capabilities are more likely to be the norm due to a variety of motivating factors. In the context of such heterogeneous smart antenna networks (HSANs), we investigate and motivate the need for a simple form of node cooperation called retransmit diversity. We show that while such a simple form of node cooperation cannot bring significant benefits to homogeneous omni-directional antenna networks, they can bring great gains (several folds improvement) to heterogeneous smart antenna networks. We then present several key properties pertaining to node cooperation in HSANs along with analytical reasoning. In the process, we identify a fundamental trade-off between exploiting smart antenna gain and cooperation gain, that undermines the ability of HSANs to leverage node cooperation to their maximum potential. To address this trade-off, we then present an adaptive cooperation mechanism and incorporate this mechanism through the design of a simple but efficient MAC protocol. The performance of the MAC protocol is evaluated through ns2 simulations along with a realistic physical layer channel model for smart antenna environments. © 2006 IEEE.


Liu C.,Georgia Institute of Technology | Sundaresan K.,United Mobile | Jiang M.,United Mobile | Rangarajan S.,United Mobile | Chang G.-K.,Georgia Institute of Technology
Proceedings - IEEE INFOCOM | Year: 2013

Small cells have become an integral component in meeting the increased demand for cellular network capacity. Cloud radio access networks (C-RAN) have been proposed as an effective means to harness the capacity benefits of small cells at reduced capital and operational expenses. With the baseband units (BBUs) separated from the radio access units (RAUs) and moved to the cloud for centralized processing, the backhaul between BBUs and RAUs forms a key component of any C-RAN. In this work, we argue that a one-one mapping of BBUs to RAUs is highly sub-optimal, thereby calling for a functional decoupling of the BBU pool from the RAUs. Further, the backhaul architecture must be made re-configurable to allow the mapping between BBUs and RAUs to be flexible and changed dynamically so as to not just optimize RAN performance but also energy consumption in the BBU pool. Towards this end, we design and implement the first OFDMA-based C-RAN test-bed with a reconfigurable backhaul that allows 4 BBUs to connect flexibly with 4 RAUs using radio-over-fiber technology. We demonstrate the feasibility of our system over a 10 km separation between the BBU pool and RAUs. Further, real world experiments with commercial off-the-shelf WiMAX clients reveal the performance benefits of our reconfigurable backhaul in catering effectively to heterogeneous user (static and mobile clients) and traffic profiles, while also delivering energy benefits in the BBU pool. © 2013 IEEE.


Apostolopoulos J.G.,United Mobile | Reibman A.R.,AT and T Labs Research
IEEE Signal Processing Magazine | Year: 2012

The challenge of estimating video quality in video communication applications is discussed. Video delivery over modern communication networks is becoming ubiquitous through its use with an ever larger range of different applications. For the viewer to experience high-quality video, the captured video should have minimal undesired attribute. The compressed video may be afflicted by compression artifacts, such as blocking, ringing, or blurring. The display device, environmental viewing conditions, and viewer have a significant effect on the perceived quality. A video quality estimator (VQE) need only be effective for its intended usage. Full-reference VQEs require access to both the decoded video and the original video in the same physical location to estimate the quality. No-reference pixel-based VQEs attempt to estimate quality by decoding the video but without access to the original. No-reference bit stream-only VQEs attempt to estimate quality without completely decoding the video to obtain decoded pixels.


Sundaresan K.,United Mobile | Rangarajan S.,United Mobile
Proceedings - IEEE INFOCOM | Year: 2012

The ability of relay networks to improve capacity and coverage has led to their adoption in next generation wireless broadband networks (WiMAX, LTE-advanced). Unlike conventional cellular networks, there is a multitude of design features that impacts the performance of these relay networks. This has consequently increased the need for efficient scheduling algorithms to optimize such design features. The focus of this work is to improve relay network throughput through adaptive resource usage in the form of two key design features - (i) adaptive frame segmentation, and (ii) spatial reuse - that are allowed by the relay standard. To this end, we design efficient scheduling algorithms that optimize these two features jointly. We provide both algorithms with performance guarantees as well as those with fast running times. Our study reveals that with the help of properly designed scheduling algorithms, adaptive resource usage can (i) boost the network throughput performance by up to 50%; and (ii) optimize network throughput effectively, providing an effect similar to dynamic relay placement. © 2012 IEEE.


Charilas D.,United Mobile
IEEE Vehicular Technology Magazine | Year: 2010

Nowadays there is a plethora of independent radio access technologies (RATs), each supporting distinct coverage, mobility, data rates, and quality of service (QoS). The cornerstone of all visions on future wireless networks is that there will be a multiaccess network environment, where users will be able to select from various available multiple heterogeneous access networks the most appropriate one to satisfy specific application requirements. On the other hand, emerging applications call for the vehicular networks to support multimedia and real-time services. © 2010 IEEE.


Fritchie S.L.,United Mobile
Proceedings of the ACM SIGPLAN International Conference on Functional Programming, ICFP | Year: 2010

When implementing a distributed storage system, using an algorithm with a formal definition and proof is a wise idea. However, translating any algorithm into effective code can be difficult because the implementation must be both correct and fast. This paper is a case study of the implementation of the chain replication protocol in a distributed key-value store called Hibari. In theory, the chain replication algorithm is quite simple and should be straightforward to implement correctly. In practice, however, there were many implementation details that had effects both profound and subtle. The Erlang community, as well as distributed systems implementors in general, can use the lessons learned with Hibari (specifically in areas of performance enhancements and failure detection) to avoid many dangers that lurk at the interface between theory and real-world computing. Copyright © 2010 ACM.


Wilson C.H.,United Mobile
Journal of surgical orthopaedic advances | Year: 2012

Recent advances in plating technology for the pediatric femur fracture have demonstrated early mobilization of the extremity and early weight bearing. Submuscular techniques allow for minimal soft tissue disruption and provide a theoretical healing advantage. This article presents results of the treatment of pediatric femur fractures using a locked submuscular bridge plating technique. The authors reviewed 16 patients between 6 and 12 years of age who sustained a femoral shaft fracture treated with minimally invasive submuscular locked plating. Patients were followed for an average of 25 months and made full weight bearing within 6 weeks of surgery. All patients achieved radiographic and clinical union with an average time of 2.6 months. Range of motion of the knee and hip were equivalent to the contralateral extremity at 2.1 months. Average time of hardware removal was 11 months. Benefits of locked plating of pediatric femur fractures include high union rates, early weight bearing, early recovery of range of motion, and minimal complications.


King A.C.,United Mobile
Respiratory Care | Year: 2012

Patients requiring prolonged mechanical ventilation are rapidly increasing in number. Improved ICU care has resulted in many patients surviving acute respiratory failure to require prolonged mechanical ventilation during convalescence. Also, mechanical ventilation is increasingly used as a therapeutic option for patients with symptomatic chronic hypoventilation, with an increased effort to predict nocturnal hypoventilation to initiate ventilation earlier. There are continued efforts by ventilator manufacturers to improve home ventilators. These factors point to a likely increase in the number of patients receiving home mechanical ventilation in the United States. Unfortunately, there are no comprehensive databases or national registry of home ventilator patients-therefore the number of home ventilator patients is unknown. There are real challenges to providing mechanical ventilation in the home, which include caregiver training, adequacy of respiratory care, and reimbursement. © 2012 Daedalus Enterprises.


Schafer R.W.,United Mobile
IEEE Signal Processing Magazine | Year: 2011

Recently, while reading a paper on heart rate monitoring using an accelerometer [1], I found myself asking the question posed by the above title. While searching for the answer, I discovered many things that seemed to be well known to others outside the field of digital signal processing (DSP) but not to me. After adding some results of my own, I presented what I had learned at a poster session at the 2011 DSP/SPE Workshop [2]. © 2006 IEEE.

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