Scalable Network Tomography for Dynamic Spectrum Access

Mobile networks have increased spectral efficiency through advanced multiplexing strategies that are coordinated by base stations (BS) in licensed spectrum. However, external interference on clients leads to significant performance degradation during dynamic (unlicensed) spectrum access (DSA). We introduce the notion of network tomography for DSA, whereby clients are transformed into spectrum sensors, whose joint access statistics are measured and used to account for interfering sources. Albeit promising, performing such tomography naively incurs an impractical overhead that scales exponentially with the multiplexing order of the strategies deployed -- which will only continue to grow with 5G/6G technologies. To this end, we propose a novel, scalable network tomography framework called NeTo-X that estimates joint client access statistics with just linear overhead, and forms a blue-print of the interference, thus enabling efficient DSA for future networks. NeTo-X's design incorporates intelligent algorithms that leverage multi-channel diversity and the spatial locality of interference impact on clients to accurately estimate the desired interference statistics from just pair-wise measurements of its clients. The merits of its framework are showcased in the context of resource management and jammer localization applications, where its performance significantly outperforms baseline approaches and closely approximates optimal performance at a scalable overhead.Comment: Accepted to IEEE INFOCOM 2024. 11 pages, 11 figure

Synchronicity: Pushing the envelope of fine-grained localization with distributed MIMO

Indoor localization of mobile devices and tags has received much attention recently, with encouraging fine-grained localization results available with enough line-of-sight coverage and enough hardware infrastructure. Synchronicity is a location system that aims to push the envelope of highly-accurate localization systems further in both dimensions, requiring less line-of-sight and less infrastructure. With Distributed MIMO network of wireless LAN access points (APs) as a starting point, we leverage the time synchronization that such a network affords to localize with time-difference-of-arrival information at the APs. We contribute novel super-resolution signal processing algorithms and reflection path elimination schemes, yielding superior results even in non-line-of-sight scenarios (with one to two walls separating client and APs). We implement and briefly evaluate Synchronicity on theWARP hardware radio platform using standard 20 MHz wireless LAN channels

EFFICACY OF ULTRASOUND WITH MAITLAND MOBILIZATION OVER SHORT WAVE DIATHERMY WITH MAITLAND MOBILIZATION IN IMPROVING THE FUNCTIONAL PERFORMANCE OF PATIENTS WITH PERIARTHRITIS SHOULDER

Objective: To investigate the effectiveness of ultrasound with Maitland mobilization over Short wave diathermy with Maitland mobilization in improving the functional performance of patients with Periarthritis of shoulder Design: A simple randomized controlled clinical trail Setting: The study was conducted in the department of physiotherapy in Ganga Hospital Coimbatore (India), Vinayaka Mission Hospital Salem (India). Subjects: 30 patients were selected randomly from the population using simple random sampling procedure (Lottery Method) and were divided into two equal groups. Intervention : The experimental group (n=15) were given Ultrasound with Maitland mobilization with 1 MHz in frequency, continuous mode and 1.5 W/cm 2 of intensity with 5cm 2 sized transducer for 10 minutes of treatment duration .The control group (n=15) were given Short wave diathermy with Maitland mobilization for period of 15 min with contra planar technique. Outcome measures: The functional performance was measured using Shoulder Pain and Disability Index (SPADI) scale. Results: In Group-A (Experimental Group ) and Group-B (Control Group), all data was expressed as mean ± , SD and was statistically analysed using paired 't' test and independent 't' test to determine the statistical difference among the parameters at 0.5% level of significance. Statistical data of SPADI showed that, Group-A is significantly different from Group-B with p<0.05; i.e 95% of significance. Conclusion: The post ultrasound Maitland mobilization is found more effective and beneficial than post SWD Maitland mobilization on shoulder functions in periarthritis. KEYWORDS: Maitland mobilizations, Short wave diathermy, Ultrasound, Periarthritis, Glides. Quick Response cod

The need for cross-layer information in access point selection algorithms

Abstract The low price of commodity wireless LAN cards and access points (APs) has resulted in the rich proliferation of high density WLANs in enterprise, academic environments, and public spaces. In such environments wireless clients have a variety of affiliation options that ultimately determine the quality of service they receive from the network. The state of the art mechanism behind such a decision typically relies on received signal strength, associating clients to that access point (AP) in their neighborhood that features the strongest signal. More intelligent algorithms have been further proposed in the literature. In this work we take a step back and look into the fundamental metrics that determine end user throughput in 802.11 wireless networks. We identify three such metrics pertaining to wireless channel quality, AP capacity in the presence of interference, and client contention. We modify the low level software functionality (firmware and microcode) of a commercial wireless adaptor to measure the necessary quantities. We then test, in a real testbed, the ability of each metric to capture end user throughput through a range of diverse network conditions. Our experimental results indicate that user affiliation decisions should be based on metrics that do not only reflect physical layer performance, or network occupancy, but also concretely capture MAC layer behavior. Based on the acquired insight, we propose a new metric that is shown to be highly accurate across all tested network scenarios

Medium access control for ad hoc networks with switched-beam antennas

M.S