NSF Grant CNS-1948511

CRII: NeTS: Beyond PHY and Chanel Measurements in Millimeter Wave: Towards Low-Overhead and Resilient Multi-hop Networking

List of personnel

  • Principal Investigator: Morteza Hashemi 
  • Graduate Students: Sravan reddy Chintareddy

Overview and Goals

In this project, our overarching goal is to develop system-level protocols and algorithms for low-overhead multi-hop mmWave networking. To achieve this, the following major goals are considered:

Goal 1: Low-overhead mmWave Beam Alignment for Multi-hop Settings: This thrust will focus on efficient and low-overhead beam alignment schemes for mmWave networks. We will formulate beam alignment based on multi-armed bandit models where successive beam alignments are identified stochastically-correlated. This method will reduce the angular beam search space and overall beam alignment overhead.

Goal 2: Multi-hop Routing Algorithm: In this thrust, we will develop a multi-path routing protocol that establishes one primary and one reserved path towards the destination to guarantee reliable and robust mmWave communication under extreme stress conditions such as blockage scenarios. Moreover, we will leverage the sub-6 GHz band for disseminating routing control messages due to the need for efficient broadcasting to reach all neighbor nodes. 

Goal 3: Buffer Allocation in Multi-hop mmWave Networks with Multi Users: This thrust will aim at investigating the problem of optimal buffer allocation in multi-hop mmWave networks with multi users, where the goal is to strike an optimal tradeoff between delay and throughput performance while providing a fair allocation across different data flows.

Evaluation plan: To validate our design and evaluate the performance of the proposed approaches, we will establish a proof-of-concept mmWave experimentation setup. In this setup, we use 60 GHz software-defined radios (SDRs) to establish a flexible platform to test different indoor and outdoor mmWave communication settings (e.g., with and without blockage).

Three images with equipment for the experiment outside on tables

Collected dataset for different outdoor scenarios are reported in the SigMF format as follows: 

Information on the SigMF Format

Key Accomplishments

Our main results along the above research directions are as follows:

(1) Dynamic and low-overhead sector sweep for directional mmWave systems: we have developed adaptive and dynamic sector sweep and beam refinement protocols to reduce the signaling overhead associated with directional communications in mmWave bands. Specifically, unlike omni-directional communications in sub-6 GHz, high data rates in mmWave come at the price of large coordination overhead due to highly directional communications needed to compensate for large channel losses. To reduce the overhead, our proposed solution takes into account short-term history of received signal strength to extract some information and dynamically adjust the beam alignment and refinement intervals. Thus, the proposed protocol with adaptive sector-sweep (SSW) intervals can efficiently react to the received signal level in order to decrease or increase the SSW intervals. In addition to an adaptive beam tracking solution, the same methodology is applied to develop an adaptive beam refinement protocol (BRP). In this case, TRN-T and TRN-R fields are appended to the signal frames only when they are needed (e.g., drop in signal level or stale beam information). 

(2) AODV-based multi-hop communications:  we investigate the performance of an AODV-type multi-hop algorithm for mmWave communication for indoor 60 GHz applications and demonstrate the benefits of multi-hop routing protocols for mmWave systems. Due to the nature of use-cases for indoor mmWave systems (e.g., real time high data rate applications), a blocked link should quickly be detected and replaced by an alternative link. As such, we propose a hop-by-hop multi-path routing protocol for switching to a reserved ready-to-use link towards the destination. We implement the proposed protocol on top of the 802.11ad PHY and MAC specification, and investigate its performance under different scenarios. Our simulations confirm the validity of the proposed approach to sustain high throughput and low latency performance under blockage and NLOS scenarios. We have also extended our investigation in mmwave to the sub-THz band that is considered as another instance of directional communication systems. 

(3) Rateless coding for multi-hop mmWave networks: we have investigated the problem of rateless coding over two-hop networks. In particular, we investigate the problem of delay-efficient and reliable data delivery in ultra-dense networks (UDNs) such as mmwave cell deployments. Considering a two-hop data delivery system, we propose a partial decode-and-forward (PDF) relaying strategy together with a simple and intuitive amicable encoding scheme for rateless codes to significantly improve user experience in terms of end-to-end delay. Simulation results verify that our amicable encoding scheme is efficient in improving the intermediate performance of rateless codes. It also verifies that our proposed PDF significantly improves the performance of the decode-and-forward (DF) strategy, and that PDF is much more robust against channel degradation, which could happen due to mmWave signal blockage.

(4) Joint mmWave and sub-6 GHz communications: we investigated the problem of integrating the sub-6 GHz and mmWave interfaces, where the sub-6 GHz interface acts as a fallback data transfer mechanism to combat blockage and intermittent connectivity of the mmWave communications. To this end, we model the mmWave channel as a two-state Markov channel and investigate the problem of scheduling data packets across the mmWave and sub-6 GHz interfaces such that the long-term average delay of the system is minimized. We prove that the optimal policy is of a threshold-type with state-dependent thresholds, i.e., data packets should always be routed to the mmWave interface as long as the number of packets in the system is smaller than the threshold that depends on the current mmWave channel state. Through numerical results, we demonstrate that under heavy traffic, integrating sub-6 GHz with mmWave can reduce the average delay by up to 80%.

(5) QoE-centic Multi-user mmWave scheduling: We have considered the multi-user scheduling problem in mmWave video streaming networks, which comprises a streaming server and several users, each requesting a video stream with a different resolution. The main objective is to optimize the long-term average quality of experience (QoE) for all users. We tackle this problem by considering the physical layer characteristics of the mmWave network, including the beam alignment overhead due to pencil-beams. To develop an efficient scheduling policy, we leverage the contextual multi-armed bandit (MAB) models to propose a beam alignment overhead and buffer predictive streaming solution. The proposed algorithm optimally balances the trade-off between the overhead and users’ buffer levels, and improves the QoE by reducing the beam alignment overhead for users of higher resolutions. We provide a theoretical guarantee for our proposed method and prove that it guarantees a sub-liner regret bound.

(6) Experimental testbed development: To establish an experimental mmWave testbed, we have procured and assembled two fully-functional mmWave SDRs in 60 GHz. The RF front end is purchased from Pi-Radio, which is a startup company partially supported by NSF grants. The RF front end is paired with Xilinx ZCU 111 RFSoC, which provides a powerful baseband unit to support real-time FPGA programming and data streaming.  

Broader Impacts


In addition to the Intellectual Merits, this project will provide societal, economic, and research impacts on developing 5G-and-beyond technologies that are considered as a centerpiece of technology innovation to provide foundations for economic growth. 5G-and-beyond and its underlying communication technology based on mmWave frequencies will enable novel applications ranging from smart cities to connected vehicles and autonomous cars. Our research has the potential to take an important step towards the development of low-overhead and resilient mmWave communication under stress conditions such as mobility and blockage scenarios.

(1) Recruiting minority students: To carry out the proposed research tasks, the PI is committed to recruiting students from under-represented and minority groups to work on this project. Currently, he is co-advising one minority MS student.

(2) High-school summer camp: The PI is currently developing a summer camp for high-school students. The summer camp is focused on teaching the students about wireless communications and software defined radios. The description of the camp can be found here: KU Engineering Camps.

(3) STEM education for K-12 students: As part of this project, the PI is participating in the TryEngineering Together program, which is powered by the IEEE. In particular, PI Hashemi so far has e-mentored several students through several engineering units. In this program, e-mentor and students read Focus Articles related to engineering and STEM fields and share their thoughts. This program increases the exposure of K-12 students from a diverse set of backgrounds and under-represented groups to the engineering and STEM fields.

Products 

  • Badnava, Babak, Sravan Reddy Chintareddy, and Morteza Hashemi. "QoE-Centric Multi-User mmWave Scheduling: A Beam Alignment and Buffer Predictive Approach." IEEE International Symposium on Information Theory (ISIT). IEEE, 2022.

  • Samarathunga C., Abouelseoud M., Sakoda K., Hashemi M., "Multi-hop Routing with Proactive Route Refinement for 60 GHz Millimeter-Wave Networks", IEEE 93rd Vehicular Technology Conference (VTC), 2021 

  • Kim, J., Kim, T., Hashemi, M., Brinton, C. G., Love, D. J. "Minimum Overhead Beamforming and Resource Allocation in D2D Edge Networks". IEEE/ACM Transactions on Networking. 2021

  • Chintareddy, S. R., Mezzavilla, M., Rangan, S., & Hashemi, M. "A Preliminary Assessment of Midhaul Links at 140 GHz using Ray-Tracing". mmNets 2021: ACM Workshop on Millimeter-Wave Networks and Sensing Systems, 2021

  • Samarathunga C., Abouelseoud M., Sakoda K., Hashemi M., "On the Benefits of Multi-hop Communication for Indoor 60 GHz Wireless Networks", IEEE Consumer Communications & Networking Conference (CCNC), 2021

  • Sun, C., Hashemi, M. "Efficient User Localization in Wireless Networks Using Active Deep Learning". In Asilomar 2021.

  • Sun, C., Naderializadeh, N., Hashemi, M. "Optimizing the Configuration of Intelligent Reflecting Surfaces using Deep Learning", IEEE Globecom Workshop, 2021

  • Kim, J., Kim, T., Hashemi, M., Brinton, C. G., Love, D. J. "Joint Optimization of Signal Design and Resource Allocation in Wireless D2D Edge Computing". In IEEE International Conference on Computer Communications (INFOCOM). 2020

  • Shang L, Hashemi M., Kim T., Perrins E., "Delay-Efficient and Reliable Data Relaying in Ultra Dense Networks using Rateless Codes", IEEE Global Communications Conference (GLOBECOM), 2020