Table 1 Symbols used for single traffic source
From: Random access with adaptive packet aggregation in LTE/LTE-A
Notation | Definition |
|---|---|
S j, i | State in Semi-Markov process |
N | Packet aggregation threshold |
λ | Packet arrival rate |
p j | Unsuccessful probability for the jth preamble transmission |
M | Transmission limit for random access |
W | Backoff window size |
\(p_{j}^{\prime }\) | Error probability caused by wireless channel for the jth preamble transmission |
p c | Preamble collision probability |
Ï€ j, i | Stationary probability for state S j, i |
p E, j | Probability that a preamble collision cannot be detected by eNB for the jth random access |
E i, j | Probability that a preamble cannot be decoded by eNB when it is sent by i+1 UEs for the jth random access |
Ï„ | Probability that as UE is sending a preamble in one subframe |
N C | Amount of preamble allocated for contention based random access |
N M | Amount of devices in the cell |
T E | Duration that starts when the UE sends a preamble and ends at the end of the random access response window |
T C | Duration that starts when the UE sends a preamble and ends when the contention resolution timer expires |
T S | Duration that starts when the UE sends a preamble and ends when a UE receives the contention resolution message from eNB |
h j | Average state holding time for state S j, 0 |
Q j | Proportion of time that a UE is at state S j, 0 |
T | Average state holding time for all states |
\(T_{j}^{\prime }\) | Duration for an unsuccessful random access at the jth try |
T j | Channel access latency if the aggregated packet is successfully delivered at jth try |
d ′ | Expected time used to deliver an aggregated packet |
d | Overall latency for the first aggregated packet |
α | Packet loss rate limit |
N max | Maximum allowed amount of aggregated packets |
β | Power saving factor to measure energy saving with packet aggregation |
d 0 | Time used for one random access with packet aggregation |