Research

Fundamentals of communications, signal processing, and mathematics toward new wireless systems

Today’s communication infrastructure enables almost global and instant connectivity. Nonetheless, we (and the machines!) demand more and more sophisticated features from wireless systems. By extrapolating the trends in communication networks, future wireless systems are likely to be equipped with a richer set of functionalities than what they have now. In this vast area, my research is at the intersection of wireless communications, signal processing, and mathematics. My current research are the following topics:

• Pillar 1 - Fundamentals: Sequences, modulation, waveforms, error-correction codes, number theory, harmonic analysis, optimization, information theory, stochastic signal processing

• Pillar 2 - Wireless for machine learning & machine learning for wireless: Distributed optimization over wireless networks, over-the-air computation, data fusion and acquisition, federated learning

• Pillar 3 - Communication systems:  End-to-end PHY designs, high-data-rate directional communication systems (millimeter wave radios, phased-antenna arrays, satellite networks, free-space optics), low-rate energy-efficient communication systems (IoT devices, LoRa, mesh networks, symbiotic radios, wake-up radios), software-defined radios, hardware impairments (e.g., phase noise, PAPR, IQ imbalance, quantization), the interference conditions (e.g., coexistence scenarios, multi-user detection, signal separability), multiple accessing schemes

• Pillar 4 - Sensing and localization: Ranging, ultra-wideband radios, synchronization, dual-function radar and communications, GNSS

Students worked on my projects:

• Safi Shams Muhtasimul Hoque - Current: Wi-Fi Standard Research Engineer at Ofinno, Previous: Intern at InterDigital

• Parker Huggins -  Current: Ph.D. Graduate student at NYU, Elza Ekrip, NSF GRFP Scholar, Previous:  Intern at NASA JPL, and DLR

• Anthony Joseph Perre (AJ) -  Current: M.Sc. at USC,  Previous: Intern at SRC Inc, NY

Some updates:

• The National Science Foundation has awarded a CAREER Award, part of its Faculty Early Career Development Program that supports junior faculty who exemplify leadership in education and research. The award is the NSF’s most prestigious recognition of early-career academic scientists and engineers, and it comes with more than $500,000 in research funding over five years.

  • CAREER: Over-the-Air Computation - Turning Wireless Networks into Computing Networks - 2025-2030

  • I will hire two Ph.D. students for this project, starting from Fall 2025 or Spring 2026. Please reach out to me if you are interested in research on communications, signal processing, and machine learning, with a strong emphasis on mathematics.

    • Qualifications: Willingness to innovate and publish, a minor degree in math, being a first author in an IEEE paper, and holding a master's degree in the areas of wireless communications, signal processing, or machine learning

Some select publications:

• A. Şahin, "On the Feasibility of Distributed Phase Synchronization for Coherent Signal Superposition," in Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)  Workshops - Integrated, Intelligent and Ubiquitous Connectivity for 6G and Beyond, Sep. 2025

• A. J.  Perre, P. Huggins, and A. Sahin, "Learning Zero Constellations for Binary MOCZ in Fading Channels" in Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Workshops - Emerging Modulation Techniques Towards 6G Networks, Istanbul, Turkey, Sep. 2025

• P. Huggins, A. J.  Perre, and A. Sahin, ”Fourier-Domain CFO Estimation Using Jutted Binary Modulation on Conjugate-Reciprocal Zeros,” in Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Istanbul, Turkey, Sep. 2025

• A. J.  Perre, P. Huggins, and A. Sahin, ”A Smooshed BMOCZ Zero Constellation for CFO Estimation Without Channel Coding,” in Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Istanbul, Turkey, Sep. 2025  

• M. Bilal, A. Sahin, and H. Arslan, “Interference-Free Backscatter Communications for OFDM-Based Symbiotic Radio,” IEEE Trans. on Cognitive Communications and Networking (Accepted), May. 2025

• A. Peerez-Neira, M. Martinez-Gost, A Sahin, S. Razavikia, C. Fischione, Kaibin Huang, “Waveforms for Computing Over the Air: A groundbreaking approach that redefines data aggregation,” in IEEE Signal Processing Magazine, vol. 42, no. 2, pp. 57-77, Mar. 2025.

• A. Gurses, G. Reddy, S. Masrur, O. Ozdemir, I. Guvenc, M. L. Sichitiu, A. Sahin, A. Alkhateeb, R. Dutta, “Digital Twins for Supporting AI Research with Autonomous Vehicle Networks,” IEEE Commun. Mag. (Accepted), Nov. 2024 

• A. Sahin, "Over-the-Air Majority Vote Computation with Modulation on Conjugate-Reciprocal Zeros," IEEE Trans. Wireless Commun (accepted).  Sep. 2024

• P. Huggins and A. Sahin, ”On the Optimal Radius and Subcarrier Mapping for Binary Modulation on Conjugate-Reciprocal Zeros,” in Proc. IEEE Military Communication Conference (MILCOM), Washington, DC, USA, Oct. 2024 (accepted)  (Available: arXiv)

• A. P. Ganesh, A. Perre, A. Sahin, I. Guvenc, and B. Floyd, ”A mmWave Software-Defined Array Platform for Wireless Experimentation at 24-29.5 GHz”, in Proc. IEEE Military Communication Conference (MILCOM), Washington, DC, USA, Oct. 2024 (accepted)

• A. Sahin, "Majority Vote Computation with Modulation on Conjugate-Reciprocal Zeros," in Proc. IEEE Global Communications Conference (GLOBECOM)  (accepted), Dec. 2024

• M. Bilal, A. Sahin, and H. Arslan, “Improving Interference Immunity for Backscatter Communications in OFDM-based Symbiotic Radio,” in Proc. IEEE Global Communications Conference (GLOBECOM)  (accepted), Dec. 2024

• A. Sahin and X. Wang, “Reliable Majority Vote Computation with Complementary Sequences for UAV Waypoint Flight Control,” IEEE Trans. Wireless Commun. Apr. 2024

• A. Sahin and H. Arslan "A Self-Healing Mesh Network without Global-Time Synchronization," IEEE International Conference on Communications (ICC), Jun. 2024

• A. Sahin, “Over-the-Air Computation Based on Balanced Number Systems for Federated Edge Learning,” IEEE Transactions on Wireless Communications, Sep. 2023. (pre-print: arXiv)

• A Sahin, "Wireless Federated 𝑘-Means Clustering With Non-Coherent Over-The-Air Computation," IEEE Military Communication Conference (MILCOM),  Boston, MA, USA, Nov. 2023

• A Sahin and X. Wang "Majority Vote Computation With Complementary Sequences for Distributed UAV Guidance," IEEE Military Communication Conference (MILCOM),  Boston, MA, USA, Nov. 2023

• M. S. Eldin, A. Sahin, V. Poor, and A. Goldsmith, "On Differential Privacy for Wireless Federated Learning with Non-coherent Aggregation," IEEE Global Communications Conference (GLOBECOM), Kuala Lumpur, Malaysia, Dec. 2023

• A. Sahin and R. Yang, "A survey on Over-the-Air Computation," IEEE Communications Surveys and Tutorials, Apr. 2023. (Available: arXiv, IEEE)

• S. Hoque and A. Sahin, "Chirp-Based Majority Vote Computation for Federated Edge Learning and Distributed Localization," IEEE Open Journal of the Communications Society Special Issue: Distributed Edge Learning in Wireless Networks, Apr. 2023. (Available: IEEE)

• A. Sahin, “Distributed Learning over a Wireless Network with Non-coherent Majority Vote Computation,” IEEE Transactions on Wireless Communications, Mar. 2023. (Available: arXiv, IEEE)

• A. Sahin, “Over-the-Air Computation Based on Balanced Number Systems for Federated Edge Learning,” IEEE Transactions on Wireless Communications, 2023. (Available: arXiv)

• S. Hoque and A. Sahin, "Chirp-Based Over-the-Air Computation for Privacy-Preserving Distributed Localization," IEEE International Black Sea Conference on Communications and Networking, Jul. 2023

• A. Sahin, M. Sichitiu, I. Guvenc, "A Millimeter-Wave Software-Defined Radio for Wireless Experimentation," IEEE INFOCOM Workshops - Computer and Networking Experimental Research using Testbeds, May 2023

• A. Sahin, "IQ data for a given TX-RX beam index for link-level analysis", https://ieee-dataport.org/documents/iq-data-given-tx-rx-beam-index-pair-link-level-analysis-60-ghz-band, Jan. 2023 

My GitHub page: 

• https://github.com/alphansahin/

More details on my research:

Over-the-air computation for machine intelligence: Over-the-air computation (OAC) refers to the computation of mathematical functions by exploiting the signal superposition property of wireless multiple-access channels. The distinct feature of OAC is that the local data at the edge devices (EDs), such as smartphones, laptops, tablets, vehicles, or sensors, is not acquired over orthogonal channels to perform certain computation tasks. Instead, the computation is handled by harnessing the interference via simultaneous transmissions. For example, suppose that the goal is to compute a function f(s1,..., sK) at a fusion node, e.g., an edge server (ES) at a base station or an access point, where sk is the symbol at the kth ED. With the separation of communication and computation tasks, the function is computed at the fusion node after each symbol is received via orthogonal channels, e.g., time-domain multiple access (TDMA). On the other hand, with OAC, the function is intended to be computed in the channel via simultaneous transmissions. As a result, radio resources are consumed only once. In this example, the key observation is that the ES is not interested in the local information but only in a function of them. By enabling snapshot calculation over the air, OAC paves the way for reducing the latency scaled by the number of nodes while addressing congestion in the spectrum. Hence, it is a fundamental and disruptive concept to the traditional way of independently handling computation and communication tasks. 

A demo that shows OAC can work for wireless federated learning in practice (without any cable or GPS-based clock synchronization!) (presented in GLOBECOM'22):

Millimeter-wave communications: Millimeter-wave communications are perceived as one of the key enablers for very high throughput systems, as the radios can benefit from highly directive communications over a large amount of bandwidth. It has been projected that millimeter-wave communications will be an important part of the 5G systems and the existing millimeter-wave standard in the Wi-Fi domain, i.e., IEEE 802.11ad, was extended to a new standard, i.e., IEEE 802.11ay, to achieve peak throughput of 20 Gbps. Therefore, new features, e.g., multiple-input-multiple-output (MIMO) and channel bonding, are expected to be integrated into the new Wi-Fi standard. However, the concepts that are well-understood for sub-6 GHz communications are not directly applicable to millimeter-wave communications. In millimeter-wave frequencies, new hardware challenges arise from practical considerations like power consumption and circuit technology. In addition, the communication channel characteristics in millimeter-wave frequencies are different. For example, the diffraction tends to be lower, and the rays arrive within several clusters. Besides that, as the effective antenna area is small for millimeter-wave frequencies, a large number of antenna elements is required to increase the received signal strength. However, the number of RF chains may not be directly scaled with the number of antenna elements in practice since an RF chain consumes a significant amount of power. Typically, hybrid beamforming approaches that exploit the phased antenna arrays (PAAs) are proposed in the literature. In this case, the transmitter and the receiver can observe the channel impulse response after an incoherent addition of the phases of the impinging rays. Hence, the optimal alignment of the beams of the transmitter and the receiver is not trivial. The large bandwidth available in these frequencies also enables accurate wireless positioning and sensing. My interests in this research topic include radio design, considering hardware impairments and limitations, wireless sensing and communications, fast beamforming, and beam tracking.

Completed projects in this area: 

In 2023, we had a project that aims to develop a low-cost and flexible millimeter-wave (mmWave) software-defined radio (SDR) solution to enable 28 GHz mmWave experiments at the Aerial Experimentation and Research Platform for Advanced Wireless (AERPAW), a community testbed awarded by the Platforms for Advanced Wireless Research (PAWR) on behalf of the National Science Foundation. The proposed solution uses radio-frequency analog-to-digital converters (RF-ADCs) and digital-to-analog converters (RF-DACs) operating at very high sample rates to transmit and receive waveforms with up to 2GHz bandwidth and PAAs at the transmitter and receiver to manipulate the beam direction. In addition to SDR development, an experiment that will be integrated into the AERPAW will also be designed.  

Several outcomes:

• Source codes: https://github.com/alphansahin/mmWaveSDR/

• Published a new dataset: A. Sahin, "IQ data for a given TX-RX beam index for link-level analysis", https://ieee-dataport.org/documents/iq-data-given-tx-rx-beam-index-pair-link-level-analysis-60-ghz-band, Jan. 2023

• An accepted paper at INFOCOM'23: A. Sahin, M. Sichitiu, I. Guvenc, "A Millimeter-Wave Software-Defined Radio for Wireless Experimentation," IEEE INFOCOM Workshops , May 2023

• The developed SDRs are as follows:

Some of my publications and standard contributions on this topic are as follows:

• A. Sahin, R. Yang, F. L. Sita, and R. Olesen, "A Comparison of SC-FDE and UW DFT-s-OFDM for Millimeter Wave Communications", IEEE International Conference on Communications (ICC), Kansas City, May 2018 

• A. Sahin, H. Lou, L.H. Sun, R. Yang, "An Analysis of Unified SU-MIMO Channel Model for mmWave Communications", IEEE Global Communications Conference Workshop on 5G Millimeter-Wave Channel Models, Washington, Dec. 2016

• IEEE 802.11ay: IEEE 802.11-17/1096, "Analog and Baseband Beam Tracking in 802.11ay", Kome Oteri, Li Hsiang Sun, Alphan Sahin, Hanqing Lou, and Rui Yang, InterDigital Communications Inc., Jul. 2017

• IEEE 802.11ay: IEEE 802.11-17/0429, "Throughput and Coverage Improvements with DFT-s-OFDM for 802.11ay", Rui Yang and Alphan Sahin, InterDigital Communications Inc., Mar. 2017

• IEEE 802.11ay: IEEE 802.11-17/0274, "Further Evaluation of Single Carrier Waveforms", Alphan Sahin and Rui Yang, InterDigital Communications Inc., Mar. 2017

• IEEE 802.11ay: IEEE 802.11-17/0048, "Performance Evaluation of Multi-DFT-spread OFDM for 802.11ay", Rui Yang and Alphan Sahin, InterDigital Communications Inc., Jan. 2017

• IEEE 802.11ay: IEEE 802.11-16/1445, "On the Single Carrier Waveforms for 11ay", Rui Yang and Alphan Sahin, InterDigital Communications Inc., Oct. 2016

• EEE 802.11ay: IEEE 802.11-16/0911, " Link Level Performance Comparisons of Open Loop, Closed Loop and Antenna Selection for SU-MIMO ", Li-Hsiang Sun, Hanqing Lou, Alphan Sahin, Rui Yang, Xiaofei Wang, Frank LaSita,  InterDigital Communications Inc., Jul. 2016

• IEEE 802.11ay: IEEE 802.11-16/0912, " EDMG-CEF Design for Control and SC PHY in MIMO Modes ", Rui Yang, Alphan Sahin, and Hanqing Lou, InterDigital Communications Inc., Jul. 2016

• IEEE 802.11ay: IEEE 802.11-16/0642, "Open Loop vs Closed Loop SU-MIMO for 11ay", Rui Yang and Alphan Sahin, InterDigital Communications Inc., May. 2016

• IEEE 802.11ay: IEEE 802.11-16/0339, "Channel Modeling with PAA Orientations", Alphan Sahin and Rui Yang, InterDigital Communications Inc., Mar. 2016

• IEEE 802.11ay: IEEE 802.11-16/0075, "On the channel model for short-range communications", Alphan Sahin, Rui Yang, and Hanqing Lou, InterDigital Communications Inc., Jan. 2016

• IEEE 802.11ay: IEEE 802.11-15/1333, "Feasibility of SU-MIMO under Array Alignment Method", Rui Yang and Alphan Sahin, InterDigital Communications Inc., Nov. 2015

Miscellaneous research topics: Communications is a very rich area. Besides my core research, I am also interested in the research challenges in the air-interface design and signal processing for miscellaneous paradigms such as biological communication systems, sensory systems, neural networks, in-vivo communications, optical communications, and terahertz systems, underwater networks, satellite communications, deep-space communications, back-scattering systems, low-power communication systems, wireless power transfer, as the fundamental transmitter and receiver signal processing methods in these areas are highly-correlated although the channel conditions and interference mechanisms can be fundamentally different. For instance, visible light communications (VLC) is one of the niche technologies in which I have worked in the past. The unique characteristics of VLC are mainly due to the fact that VLC channels offer distinct features as compared to radio-frequency (RF) systems. First, the performance of VLC systems is not affected by RF interference as the frequency of visible light is significantly higher than the RF. Second, VLC provides secure communications by inherent isolation as the visible light does not penetrate through the opaque walls. Third, multipath fading is averaged out as the area of photodetectors is very large compared to the wavelength of the visible light. Hence, the received signal strength (RSS) does not fluctuate drastically and enables accurate RSS-based localization. In addition, light-emitting diodes (LEDs) offer narrow beamwidth, which allows a more accurate angle of arrival (AOA) information at the receiver side. Therefore, VLC systems provide reliable positioning in environments where the Global Positioning System (GPS) signals cannot easily penetrate. Fourth, VLC systems can be utilized in scenarios where RF radiation is strongly attenuated, such as in underwater systems and potentially hazardous or even forbidden environments such as planes or hospitals. For example, VLC may provide a higher data rate than acoustic communications for short-range underwater environments. Lastly, VLC systems allow high data rate communications by utilizing off-the-shelf inexpensive hardware. Hence, VLC is perceived as one of the enablers for IoT, e.g., car-to-car communications, industrial devices, and toys, due to its low-cost implementation. My interests in this research topic include transceiver design,  system design for illumination, communications and localization, and physical layer security.  Some of our publications and standard contributions to VLC are as follows:

• • Y. S. Eroglu, I. Guvenc, A. Sahin, Y. Yapici, N. Pala, M. Yuksel, "Multi-Element VLC Networks: LED Assignment, Power Control, and Optimum Combining", IEEE Journal on Selected Areas in Communications - Localization, Communications and Networking with VLC, Sep. 2017

  • A. Sahin, Y. S. Eroglu, I. Guvenc, N. Pala, and M. Yuksel, "Hybrid 3D Localization for Visible Light Communication Systems", IEEE Journal of Lightwave Technology, vol.33, no.22, pp.4589-4599, Nov., 2015

  • IEEE LC TIG: IEEE 802.11-17/1748, "Usage Model: Short Range Underwater Light Communications", Alphan Sahin, Rui Yang, InterDigital Communications Inc., Nov. 2017

  • IEEE LC TIG: IEEE 802.11-17/0427, "Draft response to the Technical Feasibility Questions", InterDigital Communications Inc., Mar. 2017

Some of our presentations: