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1. EDM: An Ultra-Low Latency Ethernet Fabric for Memory Disaggregation

   https://doi.org/10.1145/3669940.3707221  

   Su, Weigao; Shrivastav, Vishal (February 2025, ACM International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS))

   Achieving low remote memory access latency remains the primary challenge in realizing memory disaggregation over Ethernet within the datacenters. We present EDM that attempts to overcome this challenge using two key ideas. First, while existing network protocols for remote memory access over the Ethernet, such as TCP/IP and RDMA, are implemented on top of the Ethernet MAC layer, EDM takes a radical approach by implementing the entire network protocol stack for remote memory access within the Physical layer (PHY) of the Ethernet. This overcomes fundamental latency and bandwidth overheads imposed by the MAC layer, especially for small memory messages. Second, EDM implements a centralized, fast, in-network scheduler for memory traffic within the PHY of the Ethernet switch. Inspired by the classic Parallel Iterative Matching (PIM) algorithm, the scheduler dynamically reserves bandwidth between compute and memory nodes by creating virtual circuits in the PHY, thus eliminating queuing delay and layer 2 packet processing delay at the switch for memory traffic, while maintaining high bandwidth utilization. Our FPGA testbed demonstrates that EDM's network fabric incurs a latency of only ~300 ns for remote memory access in an unloaded network, which is an order of magnitude lower than state-of-the-art Ethernet-based solutions such as RoCEv2 and comparable to emerging PCIe-based solutions such as CXL. Larger-scale network simulations indicate that even at high network loads, EDM's average latency remains within 1.3x its unloaded latency. 

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2. Multi-Band Full Duplex MAC Protocol (MB-FDMAC)

   https://doi.org/10.1109/JSAC.2023.3287546  

   Alkhrijah, Yazeed; Camp, Joseph; Rajan, Dinesh (September 2023, IEEE Journal on Selected Areas in Communications)

   In this paper, we propose a multi-band medium access control (MAC) protocol for an infrastructure-based network with an access point (AP) that supports In-Band full-duplex (IBFD) and multiuser transmission to multi-band-enabled stations. The Multi-Band Full Duplex MAC (MB-FDMAC) protocol mainly uses the sub-6 GHz band for control-frame exchange, transmitted at the lowest rate per IEEE 802.11 standards, and uses the 60 GHz band, which has significantly higher instantaneous bandwidth, exclusively for data-frame exchange. We also propose a selection method that ensures fairness among uplink and downlink stations. Our result shows that MB-FDMAC effectively improves the spectral efficiency in the mmWave band by 324%, 234%, and 189% compared with state-of-the-art MAC protocols. In addition, MB-FDMAC significantly outperforms the combined throughput of sub-6 GHz and 60 GHz IBFD multiuser MIMO networks that operate independently by more than 85%. In addition, we study multiple network variables such as the number of stations in the network, the percentage of mmWave band stations, the size of the contention stage, and the selection method on MB-FDMAC by evaluating the change in the throughput, packet delay, and fairness among stations. Finally, we propose a method to improve the utilization of the high bandwidth of the mmWave band by incorporating time duplexing into MB-FDMAC, which we show can enhance the fairness by 12.5%and significantly reduces packet delay by 80%. 

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3. Collaborative Hybrid ARQ for CDMA-based Reliable Underwater Acoustic Communications

   https://doi.org/10.1109/UComms.2018.8493231  

   Rahmati, Mehdi; Pompili, Dario; Petroccia, Roberto (August 2018, 2018 Fourth Underwater Communications and Networking Conference (UComms))

   Achieving high throughput and reliability in underwater acoustic networks is a challenging task due to the bandwidth-limited and unpredictable nature of the channel. In a multi-node structure, such as in the Internet of Underwater Things (IoUT), the efficiency of links varies dynamically because of the channel variations. When the channel is not in good condition, e.g., when in deep fade, channel-coding techniques fail to deliver the required information even with multiple rounds of retransmissions. An efficient and agile collaborative strategy among the nodes is required to assign appropriate resources to each link based on their status and capability. Hence, a cross-layer collaborative strategy is introduced to increase the throughput of the network by allocating unequal share of system resources to different nodes/links. The proposed solution adjusts the physical- and link-layer parameters in a collaborative manner for a Code Division Multiple Access (CDMA)-based underwater network. An adaptive Hybrid Automatic Repeat Request (HARQ) solution is employed to guarantee reliable communications against errors in poor communication links. Results are being validated using data collected from the LOON underwater testbed, which is hosted by the NATO STO Centre for Maritime Research and Experimentation (CMRE) in La Spezia, Italy. 

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4. Practical Asynchronous Distributed Key Generation

   https://doi.org/10.1109/SP46214.2022.9833584  

   Das, Sourav; Yurek, Thomas; Xiang, Zhuolun; Miller, Andrew; Kokoris-Kogias, Lefteris; Ren, Ling (May 2022, 2022 IEEE Symposium on Security and Privacy (SP))

   Distributed Key Generation (DKG) is a technique to bootstrap threshold cryptosystems without a trusted third party and is a building block to decentralized protocols such as randomness beacons, threshold signatures, and general multiparty computation. Until recently, DKG protocols have assumed the synchronous model and thus are vulnerable when their underlying network assumptions do not hold. The recent advancements in asynchronous DKG protocols are insufficient as they either have poor efficiency or limited functionality, resulting in a lack of concrete implementations. In this paper, we present a simple and concretely efficient asynchronous DKG (ADKG) protocol. In a network of n nodes, our ADKG protocol can tolerate up to t < n/3 malicious nodes and have an expected O(κn^3) communication cost, where κ is the security parameter. Our ADKG protocol produces a field element as the secret and is thus compatible with off-the-shelf threshold cryptosystems. We implement our ADKG protocol and evaluate it using a network of up to 128 nodes in geographically distributed AWS instances. Our evaluation shows that our protocol takes as low as 3 and 9.5 seconds to terminate for 32 and 64 nodes, respectively. Also, each node sends only 0.7 Megabytes and 2.9 Megabytes of data during the two experiments, respectively. 

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5. Orthogonal time-frequency space modulation for underwater mobile acoustic communications

   https://doi.org/10.1121/10.0035938  

   Xue, Yukang; Zhu, Xiyuan; Zheng, Y Rosa (February 2025, The Journal of the Acoustical Society of America)

   This paper presents a new turbo decision feedback equalizer and decoder (TDFED) for the orthogonal time-frequency space (OTFS) system of underwater mobile acoustic communications where the communication channel suffers from severe multipath and Doppler effects simultaneously. The proposed TDFED employs a set of feedforward and feedback filters in the time domain instead of the common approach that employs a normalized least mean square equalizer in the delay-Doppler domain. The receiver also utilizes low-complexity improved proportionate normalized least mean square channel estimation in the delay-Doppler domain. Practical OTFS modulation schemes are designed for acoustic transmission at a center frequency of 115 kHz and a symbol rate of 11.5 ksps (kilo-symbols-per-second). Several lake experiments in mobile communication scenarios are conducted to evaluate the proposed OTFS in comparison to the single-carrier coherent modulation (SCCM) and the orthogonal frequency division modulation (OFDM) schemes. The experimental results demonstrate that the proposed OTFS receiver effectively reduces the accuracy requirements of the Doppler compensation algorithm compared to the SCCM and OFDM schemes. The proposed TDFED algorithm achieves a much better bit error rate against long-multipath fading and severe Doppler shift than the existing delay-Doppler domain equalizers. 

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