Enhancing Radio Access Network Performance over LTE-A for Machine-to-Machine Communications under Massive Access

Table 3

Comparison results of proposed and existing methods.

Scheme	Access success prob. (%)	Avg. access delay (ms)	Avg. preamble trans.
Longer backoff scheme (max. 960) [14]	100	—	1.86
Prebackoff scheme (max. 960) [14]	100	—	1.51
ACB [14]:	68.98	—	—
M2M ACB factor = 0.5
ACB time = 16
Separate RACH resources [14]:	11.46	—	—
M2M/UE is 53/1
Dynamic allocation of	21.26	—	—
RACH resources [14]:
100% additional
subframes for M2M
dedicated access
PRA [15]	93.9	2937	—
Some methods proposed in this work
PRACH config. index	97.44	47.86	2.64
15 picocells	48.88	54.25	2.83
15 agg. points (1:k)	27.89	71.10	3.60
15 picocells + PRACH	99.94	33.47	1.89
config. index
15 agg. points (1:k) +	97.69	47.27	2.59
PRACH config. index