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To reduce the uplink channel access latency in LTE/LTE-A, we propose a Transmission Time Interval (TTI) bundling scheme for the random access procedure. With the proposed method, a UE sends multiple preambles in consecutive subframes in order to increase the success rate of random access and hence to reduce the latency. We introduce a Semi-Markov model to accurately model and analyze the random access...
A packet aggregation method is proposed in this paper to lower the packet collision rate when the random access channel is used for machine type communications (MTC) uplink channel access in LTE. With the proposed packet aggregation method, a UE triggers random access when the aggregated packets in the buffer reaches the given threshold. However, this method reduces the packet collision rate at the...
In this paper, we propose a dynamic resource allocation method to enable efficient and low-latency machine type communications (MTC) in LTE/LTE-A with the contention based random access (CBA) scheme [9]. In the proposed method, we firstly estimate the probabilities of events caused by a CBA transmission and then calculate the latency with the measured resource unit. We increase the amount of CBA resources...
To enable the efficient and low latency machine-type communications (MTC) over long term evolution (LTE), a contention based access (CBA) method is proposed. With CBA, UEs transmit packets on the randomly selected resource without having any UE specific scheduled resources. To address the problem of collision caused by CBA in high traffic load, eNB exploits the MU-MIMO detection technique to decode...
M2M/online gaming are considered as key applications in LTE and LTE-advanced networks. However, for most of these applications whose traffic is sporadic and some of them require very low latency, they are not well supported by the current LTE and LTE-advanced systems due to the large signaling overhead. This paper proposes two methods to address this problem. The first method provides a co-optimization...
This paper proposes a link adaptation method for IEEE 802.11n, which can foresightedly co-optimize the modulation and coding scheme (MCS) in the PHY layer and the frame size in the MAC layer. The link adaptation method employs Markov decision process (MDP) for modeling this crosslayer design. By solving the MDP model with a reinforcement learning which does not require a prior knowledge about the...
This paper presents a cross-layer optimization method for MAC protocol data unit aggregation, abbreviated to A-MPDU, with high throughput (HT) immediate block acknowledgement in non-competitive channel environment. We derive the goodput as a function of the transmission strategy, including the aggregated number of MPDUs and length of each MPDU of the MAC layer, and modulation and channel coding scheme...
As a key technology in future mobile communications system, OFDMA has efficient frequency utilization and strong robustness to frequency selective fading, however it's sensitive to synchronization errors. Although effects of synchronization errors on crossed timeslot's performance have been widely investigated in TDD/CDMA system, little work has done in TDD/OFDMA system. This paper analyzes the effects...
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