Bhuvana Krishnaswamy

Coexistence of Wi-Fi and LAA-LTE: Experimental evaluation, analysis and insights

LTE-A as a cellular technology has gained tremendous importance in recent years due to its high data-rates and improved data access for mobile devices. Recently, utilizing the unlicensed band as a supplementary band for LTE-A is being considered to expand the capacity of mobile systems. License-assisted access using LTE (LAA-LTE) will thus operate in the unlicensed band, and will operate in a spectrum that overlaps with Wi-Fi, another popular unlicensed-band technology. The concern is that LAA-LTE and Wi-Fi are unlikely to have mechanisms to directly coordinate with each other to address channel-sharing issues. In this paper, we study the interference impact of LAA-LTE on Wi-Fi under various network conditions using purely experimental analysis in indoor environments. The following three questions are specifically considered in this paper: (1) What are the implications of LAA-LTE usage on Wi-Fi? (2) How should LAA-LTE or Wi-Fi be configured for Wi-Fi to be less impacted? (3) How should the LAA-LTE MAC protocol be designed to be gracefully co-exist with Wi-Fi? To answer the above questions, we present comprehensive experimental results and give insights based on the results.

Time-Elapse Communication: Bacterial Communication on a Microfluidic Chip

Bacterial populations housed in microfluidic environments can serve as transceivers for molecular communication, but the data-rates are extremely low (e.g., 10-5 bits per second.). In this work, genetically engineered Escherichia coli bacteria were maintained in a microfluidic device where their response to a chemical stimulus was examined over time. The bacteria serve as a communication receiver where a simple modulation such as on-off keying (OOK) is achievable, although it suffers from very poor data-rates. We explore an alternative communication strategy called time-elapse communication (TEC) that uses the time period between signals to encode information. We identify the limitations of TEC under practical non-zero error conditions and propose an advanced communication strategy called smart time-elapse communication (TEC-SMART) that achieves over a 10x improvement in data-rate over OOK. We derive the capacity of TEC and provide a theoretical maximum data-rate that can be achieved.

When bacteria talk: Time elapse communication for super-slow networks

In this work we consider nano-scale communication using bacterial populations as transceivers. We demonstrate using a microfluidic test-bed and a population of genetically engineered Escherichia coli bacteria serving as the communication receiver that a simple modulation like on-off keying (OOK) is indeed achievable, but suffers from very poor data-rates. We explore an alternative communication strategy called time elapse communication (TEC) that uses the time period between signals to encode information. We identify the severe limitations of TEC under practical non-zero error conditions in the target environment, and propose an advanced communication strategy called smart time elapse communication (TEC-SMART) that achieves over a 10× improvement in data-rate over OOK.

Source Addressing and Medium Access Control in Bacterial Communication Networks

In this work, we focus on the problem of source addressing in multiple source single receiver bacterial communication network. We propose amplitude-addressing, where the amplitude of transmitted signal is assigned as address of the source. We analyse the performance of the network with different addressing mechanisms and propose an optimum address sequence for a given network design. We also show that amplitude-addressing implicitly solves the problem of medium access control.

nanoNS3: Simulating Bacterial Molecular Communication Based Nanonetworks in Network Simulator 3

We present nanoNS3, a network simulator for modeling Bacterial Molecular Communication (BMC) networks. nanoNS3 is built atop the Network Simulator 3 (ns-3). nanoNS3 is designed to achieve the following goals: 1) accurately and realistically model real world BMC, 2) maintain high computational efficiency, 3) allow newly designed protocols to be implemented easily. nanoNS3 incorporates the channel, physical (PHY) and medium access control (MAC) layers of the network stack. The simulator has models that accurately represents receiver response, microfluidic channel loss, modulation, and amplitude addressing designed specifically for BMC networks. We outline the design and architecture of nanoNS3, and then validate the aforementioned features through simulation and experimental results.

nanoNS3: A network simulator for bacterial nanonetworks based on molecular communication ☆

Abstract We present nanoNS3 , a network simulator for modeling Bacterial Molecular Communication (BMC) networks. nanoNS3 is built atop the Network Simulator 3 (ns-3). nanoNS3 is designed to achieve the following goals: 1) accurately and realistically model the real world BMC, 2) maintain high computational efficiency, 3) allow newly designed protocols to be implemented easily. nanoNS3 incorporates the channel, physical (PHY) and medium access control (MAC) layers of the network stack. The simulator has models that accurately represent receiver response, microfluidic channel loss, transfer rate and error analysis, modulation, and amplitude addressing designed specifically for BMC networks. We outline the design and architecture of nanoNS3 , and then validate the aforementioned features through simulation and experimental results.

Amplitude-width encoding for error correction in bacterial communication networks

In this work, we consider the problem of forward error correction in a multiple access molecular communication network with bacteria as transceivers. A number of forward error correction techniques have been developed to maximize throughput and achieve the lower bound on the bit error rate performance. All existing codes were developed for traditional networks and hence the constraints on computational complexity do not match that of bio-circuits. Designing reliable and accurate bio-circuits for operations like polynomial multiplication that are basic to FEC is extremely challenging. We propose and design Amplitude-Width Forward Error Correction, a simple and efficient FEC mechanism that can be implemented using bio-circuits reliably for real-time application. FEC techniques allow the receiver to detect and correct for errors by introducing redundancy in the message transmitted. EEC introduces redundancy by varying the on-period of the signal transmitted across senders. Senders with the same on-period are assigned amplitudes with maximum distance. Increasing the distance between amplitudes of senders with the same on-period increases the error resilience of the receiver. Bit error rate of the order of 10-2 is achieved using the proposed error correction mechanism.

Scheduled WiFi using distributed contention in WLANs: algorithms, experiments, and case-studies

The ubiquitous adoption of WiFi introduces large diversity in types of application requirements and topological characteristics. Consequently, considerable attention is being devoted to making WiFi networks controllable without compromising their scalability. However, the main MAC protocol of WiFi, distributed coordination function (DCF), is a contention-based protocol using random backoff. Thus, operating under DCF, the access of channel is hard to control and nonpredictable. In order to provide controllability of channel access in WiFi, we propose Rhythm, a MAC protocol that achieves scheduled WiFi efficiently using distributed contention. By achieving scheduled WiFi, channel access can be controlled by manipulating the schedule decision. We evaluate the performance of Rhythm through analysis, experiments, and case-studies.

Advanced Receiver Designs for Bacterial Communication with Amplitude Source Addressing

In this work, we focus on the problem of amplitude source addressing in a multiple source single receiver bacterial communication network. Amplitude addressing is an addressing mechanism where the amplitude of transmitted signal is assigned as address of the source. When multiple sources collide, receiver performs interference cancellation and minimizes collision resolution error. We propose two receiver designs for an amplitude addressing system. We show that amplitude-addressing along with an optimum receiver implicitly solves the problem of medium access control.