We study the problem of controlling phase activations for signalized junctions in an urban transportation network using local feedback information consisting of measures of the queue-lengths at the incoming lanes of each junction. Our focus is on the validation and performance evaluation through micro-simulations of the recently proposed Generalized Proportional Allocation (GPA) controller. Previous theoretical work has provided provable performance guarantees in terms of stability, and throughput optimality of the GPA controller in a continuous averaged dynamical queueing network model. In this paper, we first provide and implement two discretized versions of the GPA controller in the SUMO micro simulator. We then compare, in an artificial Manhattan-like grid, the performance of the GPA controller with those of the MaxPressure controller, which is another distributed feedback controller that requires more information than the GPA. Finally, to show that the GPA controller is easily implementable in a real-world scenario, we apply it to a previously published realistic traffic scenario for the city of Luxembourg and compare its performance with the static controller provided with the scenario as well as with the cyclic MaxPressure controller. The simulations show that the GPA controller outperforms both the fixed time and the cyclic MaxPressure controllers for the Luxembourg scenario, and behaves better than the MaxPressure pressure controller in the Manhattan-grid when the demands are low.

The problem of reliable communication over the memoryless state-dependent multiple-access channel (MAC) is considered, where the encoders and the decoder are provided with various degrees of asymmetric noisy channel state information (CSI). For the case where the encoders observe causal, asymmetric noisy CSI and the decoder observes complete CSI, inner and outer bounds to the capacity region, which are tight for the sum-rate capacity, are provided. Next, single-letter characterizations for the channel capacity regions under each of the following system settings are established: 1) the CSI at the encoders are asymmetric deterministic functions of the CSI at the decoder and the encoders have noncausal noisy CSI; 2) the encoders observe asymmetric noisy CSI with asymmetric delays and the decoder observes complete CSI; 3) a degraded message set scenario with asymmetric noisy CSI at the encoders and complete and/or noisy CSI at the decoder. The main component in these results is a generalization of a recently introduced converse coding approach for the MAC with asymmetric quantized CSI at the encoders and herein considerably extended and adapted for the noisy CSI setup.

We consider the problem of reliable communication over multiple-access channels (MAC) where the channel is driven by an independent and identically distributed state process and the encoders and the decoder are provided with various degrees of asymmetric (noisy or partial) channel state information (CSI). Namely, we provide a single letter characterization for the capacity region when the encoders have access to non-causal asymmetric partial CSI and the decoder has complete CSI. When the encoders observe asymmetric noisy CSI with asymmetric delays and the decoder observes complete CSI, we provide a single letter characterization for the capacity region. Finally, we consider a cooperative scenario with common and private messages, with noisy CSIT and complete CSIR and provide a single letter expression for the capacity region. For the cooperative scenario, we also note that as soon as the common message encoder does not have access to CSI, then for any noisy CSIT and CSIR setup it is possible to obtain a single letter characterization for the capacity region.

Minimum distances and maximum likelihood error probabilities of serial turbo codes with uniform interleaver are analyzed. It is shown that, for a fraction of interleavers approaching one as the block-length grows large, the minimum distance of serial turbo codes grows as a positive power of their block-length, while their error probability decreases exponentially fast in some positive power of their block-length, on sufficiently good memoryless channels. Such a typical code behavior contrasts the performance of the average serial turbo code, whose error probability is dominated by an asymptotically negligible fraction of poorly performing interleavers, and decays only as a negative power of the block-length. The analysis proposed in this paper relies on precise bounds of the minimum distance of the typical serial turbo code, whose scaling law is shown to depend both on the free distance of its outer constituent encoder, which determines the exponent of its sub-linear growth in the block-length, and on the effective free distance of its inner constituent encoder. The latter is defined as the smallest weight of codewords obtained when the input word of the inner encoder has weight two, and appears as a linear scaling factor for the minimum distance of the typical serial turbo code. Hence, despite the lack of concentration of the maximum likelihood error probability around its expected value, the main design parameters suggested by the average-code analysis turn out to characterize also the performance of the typical serial turbo code. By showing for the first time that the typical serial turbo code's minimum distance scales linearly in the effective free distance of the inner constituent encoder, the presented results generalize, and improve upon, the probabilistic bounds of Kahale and Urbanke, as well as the deterministic upper bound of Bazzi, Mahdian, and Spielman, where only the dependence on the outer encoder's free distance was proved.

A single-letter characterization is provided for the capacity region of finite-state multiple-access channels, when the channel state process is an independent and identically distributed sequence, the transmitters have access to partial (quantized) state information, and complete channel state information is available at the receiver. The partial channel state information is assumed to be asymmetric at the encoders. As a main contribution, a tight converse coding theorem is presented. The difficulties associated with the case when the channel state has memory are discussed and connections to decentralized stochastic control theory are presented.

A lower bound bound is established on the error probability of fixed-length block-coding systems with finite memory feedback, which can be described in terms of a time dependent finite state machine. It is shown that the reliability function of such coding systems over discrete memoryless channels is upper-bounded by the sphere-packing exponent.

Typical minimum distances and error exponents are analyzed on the 8-PSK Gaussian channel for two capacity-achieving code ensembles with different algebraic structure. It is proved that the typical group code over the cyclic group of order eight achieves both the Gilbert-Varshamov bound and the expurgated error exponent. On the other hand, the typical binary-coset codes (under any labeling) is shown to be bounded away both from the Gilbert-Varshamov bound (at any rate) and the expurgated exponent (at low rates). The reason for this phenomenon is shown to rely on the symmetry structure of the 8-PSK constellation, which is known to match the cyclic group of order eight, but not the direct product of three copies of the binary group. The presented results indicate that designing group codes matching the symmetry of the channel guarantees better typical-code performance than designing codes whose algebraic structure does not match the channel. This contrasts the well-known fact that the average binary-coset code achieves both the capacity and the random-coding error exponent of any discrete memoryless channel.

We provide a single letter characterization of the capacity region for independent, identically distributed, finite-state channels, with partial (quantized) state information, when the channel state information is available at the receiver. The partial state information is asymmetric at the encoders. The problem is practically relevant, and provides a tractable optimization problem. We also consider the case where the channel has memory.

The capacity of finite Abelian group codes over symmetric memoryless channels is determined. For certain important examples, such as m -PSK constellations over additive white Gaussian noise (AWGN) channels, with m a prime power, it is shown that this capacity coincides with the Shannon capacity; i.e., there is no loss in capacity using group codes. (This had previously been known for binary-linear codes used over binary-input output-symmetric memoryless channels.) On the other hand, a counterexample involving a three-dimensional geometrically uniform constellation is presented in which the use of Abelian group codes leads to a loss in capacity. The error exponent of the average group code is determined, and it is shown to be bounded away from the random-coding error exponent, at low rates, for finite Abelian groups not admitting Galois field structure.

The error exponent of Markov channels with feedback is studied in the variable-length block-coding setting. Burnashev's classic result is extended to finite-state ergodic Markov channels. For these channels, a single-letter characterization of the reliability function is presented, under the assumption of full causal output feedback, and full causal observation of the channel state both at the transmitter and at the receiver side. Tools from stochastic control theory are used in order to treat channels with intersymbol interference (ISI). Specifically, the convex-analytic approach to Markov decision processes is adopted in order to handle problems with stopping time horizons induced by variable-length coding schemes.

A class of serial turbo codes admitting low-density parity-check (LDPC) representation is considered. Their parity matrix has a random and a structured part. Thanks to their turbo structure, these codes are linear-time encodable, while they can be decoded as LDPC codes. Previous works enlightened the role of the inner encoder in the error floor region and suggested the use of a non-binary iterative decoding algorithm. In this paper, a density-evolution analysis is developed giving insight into the performance of these codes in the waterfall region. The inner encoder is optimized in order to guarantee the best tradeoff between error floor and threshold.

Ensembles of regular low-density parity-check codes over any finite Abelian group G are studied. The nonzero entries of the parity matrix are randomly chosen, independently and uniformly, from an arbitrary label group of automorphisms of G. Precise combinatorial results are established for the exponential growth rate of their average type-enumerating functions with respect to the code-length N. Minimum Bhattacharyya-distance properties are analyzed when such codes are employed over a memoryless G-symmetric transmission channel. In particular, minimum distances are shown to grow linearly in N with probability one, and lower bounds are provided for the typical asymptotic normalized minimum distance. Finally, some numerical results are presented, indicating that the choice of the label group strongly affects the value of the typical minimum distance.

The problem of the minimum Bhattacharyya distance of group codes over symmetric channels is addressed. Ensembles of Zm-linear codes are introduced and their typical minimum distance characterized in terms of the Gilbert- Varshamov distances associated to the subgroups of Zm. For the AWGN channel with 8-PSK as input it is shown that the typical Z8-linear code achieves the Gilbert-Varshamov bound.

We consider the reliability function of Markov channels with feedback and variable length channel codes. We extend Burnashev's [M.V. Burnashev, 1976] classic result to this case and present a single letter characterization for the reliability function.

We consider a family of codes which can be seen both as a special kind of serial turbo codes and as LDPC codes having a parity check matrix which is partly random and partly structured. These codes are linear-time encodable, thanks to the turbo structure, and can be decoded as LDPC codes. We provide an ensemble analysis for the waterfall region, on the line of classical results for serial turbo codes, and we find some design parameters.

In this paper we study ensembles of Abelian group codes on symmetric channels. Our main example is the AWGN channel where the inputs are restricted to a GU constellation admitting Zopfmas a generating group. For codes which are Zopfm-free modules, we prove a sort of Shannon theorem which exactly characterizes which are the rates for which reliable transmission is possible. In particular we prove that for the 2r-PSK constellation, group codes over Zopf- do achieve Shannon capacity. Finally, we study the performance of low density Zopf codes and we prove average convergence rate of their word error probability