Abstract
While random access presents a promising solution for efficient uplink channel access, the preamble collision rate can significantly increase when massive number of devices simultaneously access the channel. To address this issue and improve the reliability of the random access, an adaptive packet aggregation method is proposed. With the proposed method, a device does not trigger a random access for every single packet. Instead, it starts a random access when the number of aggregated packets reaches a given threshold. This method reduces the packet collision rate at the expense of an extra latency, which is used to accumulate multiple packets into a single transmission unit. Therefore, the tradeoff between packet loss rate and channel access latency has to be carefully selected. We use semi-Markov model to derive the packet loss rate and channel access latency as functions of packet aggregation number. Hence, the optimal amount of aggregated packets can be found, which keeps the loss rate below the desired value while minimizing the access latency. We also apply for the idea of packet aggregation for power saving, where a device aggregates as many packets as possible until the latency constraint is reached. Simulations are carried out to evaluate our methods. We find that the packet loss rate and/or power consumption are significantly reduced with the proposed method.
Highlights
Reliable and low-latency protocols and access methods are becoming crucial to lower the bit error rate and energy consumption and to improve the spectral efficiency in end devices
We propose an adaptive packet aggregation method for random access applied to LTE/LTE-A, as an extension to our previous work [12], to radically reduce the collision rate and/or power consumption as the number of devices and traffic load increase
We introduce an adaptive packet aggregation method for random access in LTE/LTE-A to radically reduce the preamble collision rate and/or power consumption, in particular when the number of contending terminals becomes large
Summary
Reliable and low-latency protocols and access methods are becoming crucial to lower the bit error rate and energy consumption and to improve the spectral efficiency in end devices. It requires an access period equals to 1000/36 ∗ 1 ms = 28 ms to allocate all SR of all 1000 devices These limitations call for an optimization in random access channel in view of sporadic, unpredictable, coordinated, and/or delay-bounded traffic sources so as to reduce the collision rate and improve its reliability [4]. We propose an adaptive packet aggregation method for random access applied to LTE/LTE-A, as an extension to our previous work [12], to radically reduce the collision rate and/or power consumption as the number of devices and traffic load increase. We apply a semi-Markov process [13] to model the random access in LTE/LTE-A and subsequently to derive the packet loss rate and channel access latency as functions of the number of aggregated packets.
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