ALT This paper develops a channel model for scattering from a broad class of integrated sensing and communication (ISAC) targets-robots, humans, and automobiles-based on a unified measurement campaign at 28 GHz. Nine targets are characterized from numerous transmitter–receiver configurations per target, spanning full bistatic and aspect angles and thus covering backward to forward scattering. Repeated acquisitions are collected for each configuration to capture target motion and dynamics, yielding nearly 117 000 acquisitions in total. Measurements are collected with a 2 GHz-wide channel sounder equipped with a 256-element phased-array antenna, followed by digital beamforming and super-resolution processing for reliable extraction of multiple paths in delay and 2D angle, with average estimation errors of 0.1 ns and 0.2° respectively. From these measurements, we reduce a path-specific channel representation in which the scattering is modeled as a cluster of paths whose center is defined by t

ALT We study the minimum extension degree required for a Reed–Solomon code to admit exact Fq-linear repair at the cut-set bound from every prescribed set of d helpers. Let s=d-k+1, and let Qₛ(n) be the minimum product of n pairwise coprime integers, each at least s. For every prime power q and all 3≤ k<d<n≤2d-2, we prove that the minimum degree over Fq is exactly sQₛ(n). When all surviving nodes are helpers, we also characterize the admissible extension degrees and bound the number of coordinates that can attain the cut-set bound. The required achievability follows from existing construction methods; we give a short existence proof using splitting subspaces. For a family of parameters with n>2d-2, we obtain strictly smaller extension degrees, showing that the range restriction cannot be omitted altogether. Finally, we prove that a nonlinear repair scheme attaining the cut-set bound induces an Fₚ-linear repair scheme on the same code, where p is the characteristic. Consequently, the extensi

ALT Fluid antenna arrays (FAAs) reconfigure their effective aperture by activating radiation ports from a dense set of candidate positions within a finite physical region, thereby offering geometry diversity beyond conventional fixed arrays. This paper studies arbitrary-direction far-field beam synthesis with a planar FAA. Since a fixed array adapts its beamforming weights on a predetermined spatial sampling structure, its ability to match desired beam patterns is limited when both the aperture and the number of active elements are constrained. To exploit the geometry diversity of the FAA, we propose a coarse-to-fine scheme that couples discrete port selection with continuous joint refinement. In the coarse stage, a fast Fourier transform (FFT) based phase retrieval step converts the amplitude-only beam specification into an aperture-compatible complex target, after which an FFT-tailored greedy method selects the active ports and least squares initializes their complex weights. In the fine

ALT Parallel ensembles of successive cancellation (SC)-style decoders improve error-rate performance by decoding multiple representations of the received vector. Conventional ensembles, however, keep every member active until completion. To reduce computational cost while retaining the diversity gain of ensemble decoding, we propose early ensemble selection (EES), which ranks members using intermediate decoding states and retains a prescribed numbers of members at each predefined selection stage. Within the EES framework, we propose two selection rules, namely path-metric-based selection (PM-EES) and neural-network-based selection (NN-EES). We analytically characterize the computational cost of EES through stage-dependent decoder log-likelihood ratio (LLR) update counts and provide an information-theoretically motivated criterion for choosing selection stages. Simulations on the (128,64) extended BCH code and the RM(4,8) code show that suitable selection schedules approach full-ensemble er

ALT Every explicit non-cyclic crossed product space–time code for more than four antennas has relied on transcendental structure constants, and its coding gain is therefore not bounded away from zero. We explain this phenomenon and show how to avoid it. Over a number field, the commuting-generator (tensor product) construction yields a division algebra only in the cyclic case, and a division crossed product of prime-power degree requires two places with full decomposition group; in particular, no (ℤ/2)ʳ, r≥3, crossed product division algebra exists over ℚ(i). We then introduce Abelian crossed products with a commutator twist, give the general parametric form of their codewords as a 2×2 block matrix of cyclic-algebra codewords, and prove the division property with a centralizer argument and a tame norm-residue symbol. This yields algebraic codes over ℚ(i) with non-vanishing determinants and closed-form minimum determinants: an information-lossless 4×4 (ℤ/2)² code with δₘᵢₙ=1/2000, and an in

ALT A long reflecting wall gives every wireless transmitter a mirror image, pairing its direct and reflected paths. Motivated by intelligent surfaces, we study the resulting signal point processes under two treatments: keeping the powers apart and superposing their point processes, or adding the powers transmitter by transmitter to form a recombined process. A threshold on inverse received power selects a region of transmitter locations, so Campbell's theorem reduces the mean measures to area calculations without assuming Poisson transmitters. For power-law path loss and paired fading marks, we derive the ratio of the recombined and superposed mean measures at large thresholds. The limit is independent of transmitter density and wall distance, but generally depends on the joint fading distribution. Under common fading, that dependence disappears and the limit depends only on the reflection coefficient and path-loss exponent. For Poisson transmitters, we derive paired count fluctuations and

ALT Let 2≤ k≤ n and let U≤Fq^n be a fixed (k-1)-dimensional linear code. We study the [n,k] maximum distance separable (MDS) codes over finite extensions of Fq that contain the scalar extension of U. Our approach constructs an auxiliary linear code from U. Its full-weight words characterize the desired MDS completions. We prove that U admits an [n,k] MDS completion over some finite extension of Fq if and only if d(U)≥ n-k+1. When this condition holds, the number of these MDS codes over F_q^m is \#{W≤F_q^m^n:Uotimes_FqF_q^m⊆ W, dim_{F_q^m} W=k, W is MDS}=χδ_GM(G)(q^m)/q^m-1, where G is a generator matrix of U, δ_GM(G) is its represented derived matroid, and χδ_GM(G) is its characteristic polynomial. In particular, the formula determines existence over each extension field and the least extension degree for which such an MDS code exists. Examples show that these counts may distinguish different representations of the same column matroid, while monomially inequivalent codes may have identical

ALT Determining the cross-correlation distributions between m-sequences and their decimated sequences is an important problem in sequence design. For two positive integers n and k with n=2k, this paper investigates the cross-correlation function between a binary m-sequence {u(t)} of period 2ⁿ-1 and its 2\ᵍᶜᵈ⁽ˢᵏ)+1 short-period decimated sequences {u(dt+l)}, where the decimation d=²ˢ⁄₂ₛ₊₁(2ᵏ-1)+1 satisfies 1<s<n and v₂(s)>v₂(k). The cross-correlation function is proved to be four-valued and its value distribution is completely determined. Several previously known binary cross-correlation functions are included in our result as special cases.

ALT We prove the Golomb–Welch conjecture for lattice tilings: for every n≥3 and r≥2, the integer lattice ℤⁿ admits no lattice tiling by Lee balls Bₙ(r) of radius r. Together with the classical constructions for n≤2 and for r=1, this determines all parameters for which a lattice Lee tiling exists. Equivalently, we show that every abelian Cayley graph of even degree 2n≥6 and diameter r≥2 has strictly fewer than |Bₙ(r)|vertices.

ALT Improving the throughput of the weakest users is a central objective of wireless resource allocation, and the objective around which the user-centric cell-free massive multiple-input multiple-output (UC-mMIMO) architecture is built. This paper brings the two together by formulating and solving percentile programs for UC-mMIMO networks. We maximize the sum-least-qth-percentile (SLqP) rate via downlink power control, a utility that targets the user equipments (UEs) in the lowest q percentile of the rate distribution and subsumes max-min-rate and sum-rate maximization as special cases. The problem is non-convex, non-smooth and NP-hard. The cyclic maximization approach of one of the previous percentile optimization series does not carry over: the coherent joint transmission technique introduces cross terms in the powers that destroy the block-concavity on which it relies. We develop a change of variables that restores block-concavity, yielding an algorithm with closed-form auxiliary update