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BER-performance of OFDMA with different powerloading algorithms combined with OSSA in uncorrelated Rayleigh fading; 8 users sharing 256 subcarriers.
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Whenever a communication system operates in a time-frequency dispersive radio channel, the link adaptation provides a benefit in terms of any system performance metric by employing time, frequency, and, in case of multiple users, multiuser diversities. With respect to an orthogonal frequency division multiplexing (OFDM) system, link adaptation incl...
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Citations
... In multiple antenna systems multiple users are allocated to a single time-frequency chunk and the resource allocation problem is even more complex [9]. Often, resource allocation is formulated as an optimization problem [10]. If channel state information as well as service requirements (QoS) [11] are considered, a crosslayer approach to resource allocation [12] is necessary to exploit the properties of the physical layer, channel and source (video) coding [13]. ...
... For an anecdotal example, assume four users and four resources. Let q k = 1 for all users, σ 2 = 1 and the channel gain matrix M be given below in (10). Let the interference vector z = [z 1 , z 2 , z 3 , z 4 ] = [1, 1, 1, 1] and the transmit power spectral mask constraints given below in (10). ...
... Let q k = 1 for all users, σ 2 = 1 and the channel gain matrix M be given below in (10). Let the interference vector z = [z 1 , z 2 , z 3 , z 4 ] = [1, 1, 1, 1] and the transmit power spectral mask constraints given below in (10). μ 1 μ 2 μ 3 μ 4 μ 5 μ 6 μ 7 μ 8 μ 9 μ 10 R1 1 2 1 2 3 2 3 4 3 4 R2 2 1 2 1 1 4 4 3 4 3 R3 3 3 4 3 4 1 1 1 2 2 R4 4 4 3 4 2 3 2 2 1 1 Table 1. ...
In this paper, we apply and extend the theory of one-to-one and many-to-one matching markets to the resource allocation in wireless communications. We develop a general framework to find stable matchings of users and resources based on the channel and context aware preference lists of users and resources. The score-based, maximum throughput, and proportional fair scheduler do not lead necessarily to a stable matching. We apply the user and resource proposing deferred acceptance algorithm in order to find stable matchings and to identify their properties. If the preference lists of users and resources are strict and based on the same information, e.g., the channel state, the stable matching is always unique. The optimality properties of stable matchings are characterized. The framework is illustrated by an example ad-hoc communications scenario.
... This CSI can be perfect or imperfect, and full or partial. The effects of channel estimation error and feedback delay on the performance of adaptive modulated systems can also be considered in the allocation process [17]- [19]. ...
... In transmitter design, the BER minimization can be realized using uniform bit-loading and adaptive precoding [23], [24]. Analytical studies have been performed with peak-BER or average BER (computed as arithmetic mean) approaches [17], [19]. With average BER computed as weighted arithmetic mean, the resource allocation has been performed using greedy-type algorithm [25]. ...
Bit error rate (BER) minimization and SNR-gap maximization, two robustness optimization problems, are
solved, under average power and bitrate constraints, according to the waterfilling policy. Under peak power
constraint the solutions differ and this paper gives bit-loading solutions of both robustness optimization
problems over independent parallel channels. The study is based on analytical approach, using
generalized Lagrangian relaxation tool, and on greedy-type algorithm approach. Tight BER expressions
are used for square and rectangular quadrature amplitude modulations. Integer bit solution of analytical
continuous bitrates is performed with a new generalized secant method. The asymptotic convergence of
both robustness optimizations is proved for both analytical and algorithmic approaches. We also prove
that, in the conventional margin maximization problem, the equivalence between SNR-gap maximization
and power minimization does not hold with peak-power limitation. Based on a defined dissimilarity
measure, bit-loading solutions are compared over Rayleigh fading channel for multicarrier systems. Simulation
results confirm the asymptotic convergence of both resource allocation policies. In nonasymptotic
regime the resource allocation policies can be interchanged depending on the robustness measure
and on the operating point of the communication system. The low computational effort leads to a good
trade-off between performance and complexity.
Power Line Communication (PLC) systems are currently envisioned as a possible solution for distributing multimedia contents and allowing Internet access with a capillary (already built) network without demanding further infrastructure. The real challenge for PLCs consists in providing connectivity where Public Switch Telephone Network (PSTN)-based Internet Access and/or Wi-Fi/WiMAX seem to be unable to solve the problem of Digital Divide. In this paper we introduce a new metric, i.e. the goodput, to balance transmission rate and bit error rate (BER) in resource allocation issues for Power Line Communication systems. In detail, we state the well-known integer bit-loading problem as a goodput maximization with constraints on the power consumption and the maximum decoding time. The use of Trellis Coded Modulation (TCM) allows to pursue the goodput maximization weighing error probability and transmission rate which would have otherwise been in trade-off. Numerical results are presented to stress how our solution improves system performances, both in ideal conditions and with additional impairments such as crosstalk and impulsive noise, with respect to the conventional Maximum Rate (MR) and Minimum BER (MB) approaches and to validate the suitability of TCMs in comparison with higher complexity codes.
