| 61. |
- Chuang, Allen, et al.
(författare)
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Optimal throughput-diversity-delay tradeoff in MIMO ARQ block-fading channels
- 2008
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 54:9, s. 3968-3986
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider an automatic-repeat-request (ARQ) retransmission protocol signaling over a block-fading multiple-input-multiple-output (MIMO) channel. Unlike previous work, we allow for multiple fading blocks within each transmission (ARQ round), and we constrain the transmitter to fixed rate codes constructed over complex signal constellations. In particular, we examine the general case of average input-power-constrained constellations with a fixed signaling alphabet of finite cardinality. This scenario is a suitable model for practical wireless communications systems employing orthogonal frequency division multiplexing (OFDM) techniques over a MIMO ARQ channel. Two cases of fading dynamics are considered, namely, short-term static fading wherechannel fading gains change randomly for each ARQ round, and long-term static fadingwhere channel fading gains remain constant over all ARQ rounds pertaining to a given message. As our main result, we prove that for the block-fading MIMO ARQ channel with a fixed signaling alphabet satisfying a short-term power constraint, the optimal signal-to-noise ratio (SNR) exponent is given by a modified Singleton bound, relating all the system parameters. To demonstrate the practical significance of the theoretical analysis, we present numerical results showing that practical Singleton-bound-achieving maximum distance separable codes achieve the optimal SNR exponent.
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| 62. |
- Como, Giacomo
(författare)
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Group codes outperform binary-coset codes on nonbinary symmetric memoryless channels
- 2010
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448. ; 56:9, s. 4321-4334
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 63. |
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| 64. |
- Coskun, Mustafa C., et al.
(författare)
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Successive Cancellation Decoding of Single Parity-Check Product Codes: Analysis and Improved Decoding
- 2023
-
Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 69:2, s. 823-841
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Tidskriftsartikel (refereegranskat)abstract
- A product code with single parity-check component codes can be described via the tools of a multi-kernel polar code, where the rows of the generator matrix are chosen according to the constraints imposed by the product code construction. Following this observation, successive cancellation decoding of such codes is introduced. In particular, the error probability of single parity-check product codes over binary memoryless symmetric channels under successive cancellation decoding is characterized. A bridge with the analysis of product codes introduced by Elias is also established for the binary erasure channel. Successive cancellation list decoding of single parity-check product codes is then described. For the provided example, simulations over the binary input additive white Gaussian channel show that successive cancellation list decoding outperforms belief propagation decoding applied to the code graph. Finally, the performance of the concatenation of a product code with a high-rate outer code is investigated via distance spectrum analysis. Examples of concatenations performing within 0.7 dB from the random coding union bound are provided.
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| 65. |
- Cresp, Gregory, et al.
(författare)
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Design of Sequence Family Subsets Using a Branch and Bound Technique
- 2009
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Ingår i: IEEE Transactions on Information Theory. - : IEEE. - 0018-9448 .- 1557-9654. ; 55:8, s. 3847-3857
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Tidskriftsartikel (refereegranskat)abstract
- The number of spreading sequences required for Direct Sequence Code Division Multiple Access (DS-CDMA) systems depends on the number of simultaneous users in the system. Often a sequence family provides more sequences than are required; in many cases the selection of the employed sequences is a computationally intensive task. This selection is a key consideration, as the properties of the sequences assigned affect the error performance in the system. In this paper, a branch and bound algorithm is presented to perform this selection based on two different cost functions. Numerical results are presented to demonstrate the improved performance of this algorithm over previous work.
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| 66. |
- Danev, Danyo, et al.
(författare)
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On a sequence of cyclic codes with minimum distance six
- 2000
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448 .- 1557-9654. ; 46:2, s. 673-674
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Tidskriftsartikel (refereegranskat)abstract
- A sequence of q-ary cyclic codes is analyzed. For each finite field GF (q), q=4, there is a code with parameters [n, k, d, q] = [q(q-1)+1, q(q-1)-6, 6,q]. All these codes are n-, k-, and d-optimal, with only one exception. The dual codes are considered. Their true minimum distances are calculated in the range 4=q=32.
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| 67. |
- Do, Hieu T., et al.
(författare)
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Layered Coding for the Interference Channel With a Relay
- 2014
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 60:10, s. 6154-6180
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies and derives new results for the interference channel with a relay (ICR). Three inner bounds for the discrete memoryless ICR are proposed, based on three coding strategies that employ layered code at the relay. The first scheme is inspired by layered noisy network coding, proposed by Lim et al. for the two-way relay channel, the second and the third schemes rely on simpler encoding and decoding processes, dubbed layered quantize-forward. Performance of the proposed schemes is investigated for two classes of channels with Gaussian noise: the interference channel with in-band relay reception/out-of-band relay transmission and the interference with in-band relay reception/in-band relay transmission. For the former class of channels, it is shown that the first proposed scheme achieves the same inner bound as the generalized hash-forward scheme with incremental binning. In addition, the inner bound is within 0.5 bit of the capacity region under certain conditions on the channel parameters. For the latter class of channels, new upper bounds on sum-rate are established by extending known upper bounds for symmetric channels. The first inner bound is shown to be within 0.5 bit of the capacity region if the relay's power exceeds a certain threshold, which depends on channel parameters. Numerical examples show that the proposed schemes can achieve significantly higher sum-rates when compared with other compress-forward schemes. Analysis also reveals a tradeoff between achievable rates, coding delay, and complexity of the proposed schemes. Results in this paper provide a better understanding of coding for the ICR, in particular, they show that layered coding is a beneficial element in multiuser networks with relays.
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| 68. |
- Du, Jinfeng, et al.
(författare)
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Scalable Capacity Bounding Models for Wireless Networks
- 2016
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Ingår i: IEEE Transactions on Information Theory. - : IEEE Press. - 0018-9448 .- 1557-9654. ; 62:1, s. 208-229
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Tidskriftsartikel (refereegranskat)abstract
- The framework of network equivalence theory developed by Koetter et al. introduces a notion of channel emulation to construct noiseless networks as upper (respectively, lower) bounding models, which can be used to calculate the outer (respectively, inner) bounds for the capacity region of the original noisy network. Based on the network equivalence framework, this paper presents scalable upper and lower bounding models for wireless networks with potentially many nodes. A channel decoupling method is proposed to decompose wireless networks into decoupled multiple-access channels and broadcast channels. The upper bounding model, consisting of only point-to-point bit pipes, is constructed by first extending the one-shot upper bounding models developed by Calmon et al. and then integrating them with network equivalence tools. The lower bounding model, consisting of both point-to-point and point-to-points bit pipes, is constructed based on a two-step update of the lower bounding models to incorporate the broadcast nature of wireless transmission. The main advantages of the proposed methods are their simplicity and the fact that they can be extended easily to large networks with a complexity that grows linearly with the number of nodes. It is demonstrated that the resulting upper and lower bounds can approach the capacity in some setups.
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| 69. |
- Dubrova, Elena
(författare)
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A Scalable Method for Constructing Galois NLFSRs With Period 2(n)-1 Using Cross-Join Pairs
- 2013
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 59:1, s. 703-709
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Tidskriftsartikel (refereegranskat)abstract
- A method for constructing n-stage Galois NLFSRs with period 2(n) - 1 from n-stage maximum length LFSRs is presented. Nonlinearity is introduced into state cycles by adding a non-linear Boolean function to the feedback polynomial of the LFSR. Each assignment of variables for which this function evaluates to 1 acts as a crossing point for the LFSR state cycle. The effect of non-linearity is cancelled and state cycles are joined back by adding a copy of the same function to a later stage of the register. The presented method requires no extra time steps and it has a smaller area overhead compared to the previous approaches based on cross-join pairs. It is feasible for large n.
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| 70. |
- Dubrova, Elena
(författare)
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A Transformation From the Fibonacci to the Galois NLFSRs
- 2009
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448 .- 1557-9654. ; 55:11, s. 5263-5271
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Tidskriftsartikel (refereegranskat)abstract
- Conventional nonlinear feedback shift registers (NLFSRs) use the Fibonacci configuration in which the feedback is applied to the last bit only. In this paper, we show how to transform a Fibonacci NLFSR into an equivalent NLFSR in the Galois configuration, in which the feedback can be applied to every bit. Such a transformation can potentially reduce the depth of the circuits implementing feedback functions, thus decreasing the propagation time and increasing the throughput.
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