Evaluation of summary quality is particularly crucial within the scientific domain, because it facilitates efficient knowledge dissemination and automated scientific information retrieval. This article presents conceptual and experimental analyses of scientific summarization, highlighting the inadequacies of traditional evaluation methods. These methods, including \( n \) -gram overlap calculations, embedding comparisons, verification, and QA-based approaches, often fall short in providing explanations, grasping scientific concepts, or identifying key content. Correspondingly, we introduce the Facet-aware Metric (FM), employing LLMs for advanced semantic matching to evaluate summaries based on different facets. The facet granularity is tailored to the structure of scientific abstracts, offering an integrated evaluation approach that is not fragmented, while also providing fine-grained interpretability. Recognizing the absence of an evaluation benchmark in the scientific domain, we curate a Scientific abstract summary evaluation Dataset (ScholarSum) with facet-level annotations. Our findings confirm that FM offers a more logical approach to evaluating scientific summaries. In addition, fine-tuned smaller models can compete with LLMs in scientific contexts, while LLMs have limitations in learning from in-context information in scientific domains. We hope our benchmark inspires better evaluation metrics and future enhancements to LLMs: https://github.com/iriscxy/ScholarSum .

Abstract The IEEE 802.16/WiMAX standard has fully embraced multi‐antenna technology and can, thus, deliver robust performance and high transmission rates. Nevertheless, due to its inherent cost concerns, a WiMAX mobile station (MS) should preferably contain fewer radio frequency (RF) chains than antenna elements. This is because the former is often substantially more expensive than the latter. Thus, antenna selection, wherein a subset of antennas is dynamically selected to connect to the limited number of RF chains for transceiving, is a highly appealing performance enhancement technique for multi‐antenna WiMAX terminals. In this paper, a novel protocol for antenna selection in space division multiple access (SDMA) transmission is developed for the next‐generation IEEE 802.16 mobile stations. Both locally and globally optimal selection rules are considered together with various linear precoding designs at the base station (BS). The proposed protocol can readily accommodate various channel situations (e.g., reciprocal and non‐reciprocal channels). As demonstrated by analysis and simulation, the proposed protocol delivers considerable performance improvement over conventional IEEE 802.16 terminals that lack antenna selection capability. Moreover, the proposed protocol leverages the existing signaling method defined in IEEE 802.16, thereby incurring a negligible signaling overhead and requiring only minimal modifications of the standard. To the best of our knowledge, this paper represents the first effort to support antenna selection capability for SDMA transmissions in IEEE 802.16 mobile stations. Copyright © 2009 John Wiley & Sons, Ltd.

Network coding has been shown to improve throughput, minimize delay and economize the energy requirements in wireless networks. This paper presents an algebraic polyphase approach to the wireless linear network coding problem. By modeling wireless nodes as consisting of linear periodic time varying filters, the model incorporates realistic constraints including omni directionality of transmissions, half-duplex operation and interference effects. A rank criterion is introduced, which together with the transmission constraints, constitutes the necessary and sufficient conditions for the existence of a wireless network code.

Network coding in wired networks has been shown to achieve considerable throughput gains relative to traditional routing networks. While the ergodic capacity of wireless multihop networks is unknown, the scaling of capacity with the number of nodes (n) has recently received increasing attention. While existing works mainly focus on networks with n source-destination pairs, this paper deals with capacity scaling in any-to-any wireless links, where each node communicates with all other nodes. Complex field network coding (CFNC) is adopted at the physical layer to allow n nodes exchanging information with simultaneous transmissions from multiple sources. A hierarchical CFNC-based scheme is developed and shown to achieve asymptotically (as n rarr infin) optimal quadratic capacity scaling in a dense network, where the area is fixed and the density of nodes increases. This is possible by dividing the network into many clusters, with each cluster sub-divided into many sub-clusters, hierarchically.

The IEEE 802.16/WiMAX standards has fully embraced multi-antenna technology and can, thus, deliver robust performance and high transmission rates. Nevertheless, due to its inherent cost concerns, a WiMAX mobile station (MS) should preferably contain fewer radio frequency (RF) chains than antenna elements. Thus, antenna selection, wherein a subset of antennas is dynamically selected to connect to the limited number of RF chains for transceiving, is a highly appealing performance enhancement technique for multiantenna WiMAX terminals. In this paper, a novel protocol for antenna selection in space division multiple access (SDMA) transmission is developed for the next-generation IEEE 802.16 mobile stations. Both locally and globally optimal selection rules are considered at the base station (BS). The proposed protocol can readily accommodate various channel situations (e.g., reciprocal and non-reciprocal channels). As demonstrated by analysis and simulation, the proposed protocol delivers considerable performance improvement over conventional IEEE 802.16 terminals that lack antenna selection capability. Moreover, the proposed protocol leverages the existing signaling method defined in IEEE 802.16, thereby incurring a negligible signaling overhead and requiring only minimal modifications of the standard.

Multi-source relay-based cooperative communications can achieve spatial diversity gains, enhance coverage and potentially increase capacity when multiuser detection is used to effect maximum likelihood demodulation. If considered for large networks, traditional relaying entails loss in spectral efficiency that can be mitigated through network coding at the physical layer. These considerations motivate the complex field network coding (CFNC) approach introduced in this paper. Different from network coding over the Galois field, where wireless throughput is limited as the number of sources increases, CFNC always achieves throughput as high as 1/2 symbol per source per channel use. In addition to improved throughput, CFNC- based relaying achieves full diversity gain regardless of the underlying signal-to-noise-ratio (SNR) and the constellation used. Furthermore, the CFNC approach is general enough to allow for transmissions from sources to a common destination as well as simultaneous information exchanges among sources.

Without being necessary to pack multiple antennas per terminal, cooperation among distributed single-antenna nodes offers resilience to shadowing and can, in principle, enhance the performance of wireless communication networks by exploiting the available space diversity. Enabling the latter however, calls for practically implementable protocols to cope with errors at relay nodes so that simple receiver processing can collect the diversity at the destination. To this end, we derive in this paper a class of strategies whereby decoded bits at relay nodes are scaled in power before being forwarded to the destination. The scale is adapted to the signal-to-noise-ratio (SNR) of the source-relay and the intended relay-destination links. With maximum ratio combining (MRC) at the destination, we prove that such link-adaptive regeneration (LAR) strategies effect the maximum possible diversity while requiring simple channel state information that can be pragmatically acquired at the relay. In addition, LAR exhibits robustness to quantization and feedback errors and leads to efficient use of power both at relay as well as destination nodes. Analysis and corroborating simulations demonstrate that LAR relays are attractive across the practical SNR range; they are universally applicable to multibranch and multi-hop uncoded or coded settings regardless of the underlying constellation; and outperform existing alternatives in terms of error performance, complexity and bandwidth efficiency.

We consider a two-person zero-sum mutual information game between one jammer (J) and one relay (Rfr) in both nonfading and fading scenarios. Assuming that the source (S) and the destination (D) are unaware of the game, we derive optimal pure or mixed strategies forJand Rfr depending on the link qualities and whether the players are active during theSrarrDchannel training. In nonfading scenarios, when bothJand Rfr have full knowledge of the source signal, linear jamming (LJ) and linear relaying (LR) are shown optimal in the sense of achieving Nash equilibrium. When theSrarrJandSrarrRfr links are noisy, LJ strategies (pure or mixed) are still optimal under LR. In this case, instead of always transmitting with full power as when theSrarrRfr link is perfect, Rfr should adjust the transmit power according to its power constraint and the reliability of the source signal it receives. Furthermore, in fading scenarios, it is optimal forJto jam only with Gaussian noise if it cannot determine the phase difference between its signal and the source signal. When LR is considered with fading, Rfr should forward with full power when theSrarrRfr link is better than the jammedSrarrDlink, and defer forwarding otherwise. Optimal parameters are derived based on exact Nash equilibrium solutions or upper and lower bounds when a closed-form solution cannot be found.

We consider a two-person zero-sum mutual information game between one jammer (J) and one relay (R), in a non-fading scenario. Supposing that the source (S) and the destination (D) are unaware of the game, we derive optimal pure or mixed strategies for J and R depending on the link qualities and whether the players are active during the S rarr D channel training. When both J and R have full knowledge of the source signal, the optimal strategies amount to linear jamming (LJ) and linear relaying (LR), respectively. When the S rarr J and S rarr R links are noisy, LJ strategies (pure or mixed) are still optimal under LR. In this case, instead of always transmitting with full power as when the S rarr R link is perfect, R should adjust transmit-power according to its power constraint and the reliability of the source signal it receives.

Cooperative communication systems using various relay strategies can achieve spatial diversity gains, enhance coverage, and potentially increase capacity. For the practically attractive decode-and-forward (DF) relay strategy, we derive a high-performance low-complexity coherent demodulator at the destination in the form of a weighted combiner. The weights are selected adaptively to account for the quality of both source-relay-destination and source-destination links. Analysis proves that the novel coherent demodulator can achieve the maximum possible diversity, regardless of the underlying constellation. Its error performance tightly bounds that of maximum-likelihood (ML) demodulation, which provably quantifies the diversity gain of ML detection with DF relaying. Simulations corroborate the analysis and compare the performance of the novel decoder with existing diversity-achieving strategies including analog amplify-and-forward and selective-relaying.

We consider broadcasting to multiple destinations with uneven quality receivers. Based on their quality of reception, we group destinations in tiers and transmit using hierarchical modulations. These modulations are known to offer a practical means of achieving variable error protection of the broadcasted information to receivers of variable quality. After the initial broadcasting step, tiers successively re-broadcast part of the information they received from tiers of higher-quality to tiers with lower reception capabilities. This multi-tier cooperative broadcasting strategy can accommodate variable rate and error performance for different tiers but requires complex demodulation steps. To cope with this complexity in demodulation, we derive simplified per-tier detection schemes with performance close to maximum-likelihood and ability to collect the diversity provided as symbols propagate through diversified channels across successive broadcastings. Error performance is analyzed and compared to (non)-cooperative broadcasting strategies. Simulations corroborate our theoretical findings.

Combining multi-source cooperation and link- adaptive regenerative techniques, we develop a novel protocol capable of achieving diversity up to the number of cooperating users and larger coding gains without incurring the overhead of cyclic redundancy check (CRC) codes. The resulting protocol can be further optimized to take advantage of the information provided by CRC when available. Simulations confirm our theoretical assessments.

User cooperation can provide spatial transmit diversity gains, enhance coverage and potentially increase capacity. Existing works have focused on two-user cooperative systems with perfect channel state information at the receivers. In this paper, we develop several distributed space-time processing schemes for general N-user cooperative systems, which do not require channel state information at either relays or destination. We prove that full spatial diversity gain can be achieved in such systems. Simulations demonstrate that these cooperative schemes achieve significant performance gain

User cooperation can provide spatial transmit diversity gains, enhance coverage and potentially increase capacity. Existing works have focused on two-user cooperative systems with perfect channel state information at the receivers. In this paper, we develop several distributed space-time processing schemes for general TV-user cooperative systems, which do not require channel state information at either relays or destination. We prove that full spatial diversity gain can be achieved in such systems. Simulations demonstrate that these cooperative schemes achieve significant performance gain.