An adaptivecoding and modulation transmission scheme applicable for third-generation mobile-satellite systems is proposed in this paper. The transmitter dynamically selects the optimum coding and modulation scheme ac...
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ISBN:
(纸本)0780370058
An adaptivecoding and modulation transmission scheme applicable for third-generation mobile-satellite systems is proposed in this paper. The transmitter dynamically selects the optimum coding and modulation scheme according to the environment in order to maximize the spectrum and power efficiency. A constant average Bit Error Rate (BER) is maintained without changing (or with a very small change to) the transmitted power, and hence the scheme eases the power control requirements. In addition, a higher throughput can be achieved compared to fixed (non adaptive) systems. Unlike other adaptive transmission systems, in our work the adaptation is based on the Rice factor. The paper also discusses a Rice factor estimation algorithm.
We design a self-exploratory reinforcement learning (RL) framework, based on the Q-learning algorithm, that enables the base station (BS) to choose a suitable modulation and coding scheme (MCS) that maximizes the spec...
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ISBN:
(纸本)9781728109602
We design a self-exploratory reinforcement learning (RL) framework, based on the Q-learning algorithm, that enables the base station (BS) to choose a suitable modulation and coding scheme (MCS) that maximizes the spectral efficiency while maintaining a low block error rate (BLER). In this framework, the BS chooses the MCS based on the channel quality indicator (CQI) reported by the user equipment (UE). A transmission is made with the chosen MCS and the results of this transmission arc converted by the BS into rewards that the BS uses to learn the suitable mapping from CQI to MCS. Comparing with a conventional fixed look-up table and the outer loop link adaptation, the proposed framework achieves superior performance in terms of spectral efficiency and BLER.
The performance of multicarrier systems can be considerably degraded because of inter-carrier interference (ICI) caused by a carrier frequency offset (CFO) between the transmitter and the receiver. A recently develope...
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ISBN:
(纸本)9781509043613
The performance of multicarrier systems can be considerably degraded because of inter-carrier interference (ICI) caused by a carrier frequency offset (CFO) between the transmitter and the receiver. A recently developed multicarrier modulation technique, referred to as uniform filtered multicarrier (UFMC), improves the robustness against CFO, thereby relaxing the synchronization requirements, consequently providing energy efficient and low latency transmissions. However, the goodput (GP) of the system still rapidly drops with increasing CFO when using the classical adaptive modulation and coding (AMC) schemes based on the SNRs of the subcarriers, because they ignore the presence of the CFO-induced ICI. To tackle this problem, this contribution performs the AMC, also taking into account the ICI caused by the CFO, and thereby achieving a significant increase of the GP.
In this paper, we construct an adaptive modulation and coding (AMC) protocol for a wireless communication system model that contains a transmitter, receiver and relay. The constructed AMC model is simulated and compar...
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ISBN:
(纸本)9781479948741
In this paper, we construct an adaptive modulation and coding (AMC) protocol for a wireless communication system model that contains a transmitter, receiver and relay. The constructed AMC model is simulated and compared with non-cooperative AMC model. In cooperative AMC model, a willing to cooperate relay listens the ongoing transmission between transmitter and receive, and helps transmitter if it is necessary. Channel is assumed as slow changing Nakagami-m fading. Channel is modelled as Markov chain and each AMC mode is assigned to a Markov state. The effect of target packet error rate (PER) is investigated. Simulation results shows that constructed cooperative AMC model provides performance gain.
Broadcasting live digital TV to a small battery-powered handheld device is very challenging. One of the evolving technologies to provide such services is DVB-H (Digital Video Broadcasting over Handheld). Wireless chan...
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ISBN:
(纸本)9781424451234
Broadcasting live digital TV to a small battery-powered handheld device is very challenging. One of the evolving technologies to provide such services is DVB-H (Digital Video Broadcasting over Handheld). Wireless channels constitute a fast varying environment that is hostile to reliable communications. adaptive modulation and coding (AMC) is one of the most promising mechanisms to cope with the dynamic fading of wireless channels. However, the broadcast nature of DVB-H systems restricts the use of AMC as the transmitter must adapt to the user experiencing the worst channel. This would constitute a penalty to other users experiencing good channels. In this paper, a novel framework for AMC is proposed for broadcast DVB-H systems. The transmitted frames are arranged such that higher modulation symbols are transmitted followed by lower modulation symbols. Each group of symbols having the same modulation technique are arranged such that higher code rates (i.e. weaker codes) are transmitted first and then incremental symbols (constituting stronger codes) are transmitted afterwards. The proposed framework is then deployed as a power saving mechanism since power consumption has always been a crucial challenge for handheld devices. The proposed adaptive receiver adjusts its modulation and coding configuration to receive and detect the minimal amount of bits that guarantee a target Bit Error Rate (BER) performance. This is shown to result in significant potential for saving of reception and processing powers (up to 71.875%). Numerical analysis for the power saving potential and BER performance of the proposed scheme is performed for flat Rayleigh fading channel. Simulation results for the operation of DVB-H under the proposed scheme in a Typical Urban 6-paths (TU6) channel are presented. Finally, the effect of adaptation rate (i.e. how often the modulation and coding are allowed to change) on power saving potential is investigated.
This paper considers a wireless cooperative communication system with the adaptive modulation and coding (AMC). We take the joint relay and AMC mode selection as two time-scales of optimization problems, which aim at ...
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This paper considers a wireless cooperative communication system with the adaptive modulation and coding (AMC). We take the joint relay and AMC mode selection as two time-scales of optimization problems, which aim at maximizing the achievable data rate. We treat the best relay selection as a long-term objective and the best AMC mode selection as a short-term objective, to limit the signaling overhead for the wireless communication system. However, the evaluation of the achievable data rate for any of relay and AMC mode combinations needs the estimation of the wireless channel. To this end, we propose an online optimization-while-estimation algorithm based on discrete stochastic approximation to jointly solve both the relay and AMC selection problems. The algorithm requires only per-frame channel sampling and estimation in each algorithm iteration, and approaches the optimal achievable data rate asymptotically. Simulation results show that our proposed algorithm can quickly converge to the maximum achievable data rate.
This paper tackles the constellation and channel coding rate selection problem in adaptive modulation and coding (AMC) for MIMO systems. Based on information theoretical results in finite blocklength analysis of chann...
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This paper tackles the constellation and channel coding rate selection problem in adaptive modulation and coding (AMC) for MIMO systems. Based on information theoretical results in finite blocklength analysis of channel capacity, a new selecting rule is proposed for narrow-band MIMO systems, and further extended to wide-band MIMO OFDM systems over channels subject to frequency-selective fading. When applied to Long Term Evolution (LTE) systems, the proposed selecting rule yields better performance in comparison with existing rules in the literature.
It is challenging to design effective scheduling algorithms for multimedia transmissions over wireless channels that employ adaptive modulation and coding (AMC). On the one hand, it is desirable for the overall system...
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It is challenging to design effective scheduling algorithms for multimedia transmissions over wireless channels that employ adaptive modulation and coding (AMC). On the one hand, it is desirable for the overall system throughput to be enhanced by taking advantage of multi-user diversity. On the other hand, fairness or QoS guarantees need to be maintained for individual users, especially in the case of multimedia applications that have strict delay requirements. In this paper, we propose a novel scheduling algorithm called QoS-based cross-layer scheduling (QoS-CLS) to achieve a good design tradeoff. To maximize the system throughput, the algorithm takes into account the information on both the physical layer and the data link layer to schedule user transmissions. Using cross-layer information, the scheduling problem is formulated as a Markov Decision Process and the optimal decision policy (based on the channel status, traffic state, and buffer status of each traffic flow) is pre-calculated by linear programming. This policy is then stored in the system for scheduling in real-time. Simulation results show that QoS-CLS can greatly enhance the channel throughput compared to existing algorithms because of its cross-layer QoS consideration and the optimization method. Moreover, it can provide QoS guarantees while achieving efficient resource sharing among different traffic flows.
In this paper, a novel cross-layer adaptive modulation and coding scheme that optimizes the overall packet loss (by both transmission errors and excessive delays) probability under a given arrival process is developed...
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In this paper, a novel cross-layer adaptive modulation and coding scheme that optimizes the overall packet loss (by both transmission errors and excessive delays) probability under a given arrival process is developed. To this end, an improved Large Deviations approximation for the fraction of packets that suffer from excessive queuing delay is proposed. This approximation is valid for G/G/1 queues with infinite buffers that are driven by stationary arrival and service processes which satisfy certain conditions. Such models can capture the time correlations in the amount of traffic generated by streaming media sources and the time varying service capacity of a wireless link. Through numerical examples, the proposed AMC policy is shown to achieve a significant reduction in the overall packet loss rate compared to previously proposed schemes. This algorithmic performance gain can be translated into a sizeable decrease in the required transmit power or an analogous increase in the rate of the arrival process, subject to a given maximum packet loss rate Quality of Service constraint. Furthermore, the proposed AMC policy can be combined with ARQ in order to achieve an even lower overall packet loss probability.
For the problem of allocating radio resources in the downlink of a CDMA network studied in [1], the modulation and coding schemes, numbers of multicodes, and transmit powers used for all mobile stations (MS's) are...
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For the problem of allocating radio resources in the downlink of a CDMA network studied in [1], the modulation and coding schemes, numbers of multicodes, and transmit powers used for all mobile stations (MS's) are jointly chosen so as to maximize the total transmission bit rate during each scheduling interval, subject to certain constraints. The approach employs discrete mathematical programming, which is potentially complex, and analytical solutions are not available. In this paper, sub-optimal approaches are examined. In particular, analytical expressions are derived for optimal resource allocation involving a single MS. Based on the single-MS solution, a sub-optimal, sequential optimization procedure for multiple MS's is presented. Numerical results show that when the order for allocating resources to MS's is judiciously chosen based on the MS channel conditions and/or traffic loads, the sequential solution is an attractive alternative to the more complex joint optimization. This is especially true when radio resources are scarce.
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