 provided that a single reservation is made per user per talk spurt. Note that in practice, very small values of TAE may not result in separate reservation requests. Since the transitions from state 1 to state 0 and vice versa are independent, the mean time MAE between active state entries is the sum of the mean time in each state; i.e., UAE = MTS + MSP. Therefore, the mean rate of arrival RAE of transitions into the active state is given as RAE = 1/MAE. The voice capacity assumes the use of a 12.2 kbps mode of 3GPP AMR codec with a 50% voice activity factor, provided that the percentage of users in outage is less than 2%, where a user is defined to have experienced outage if more than 2% of the VoIP packets are dropped, erased, or otherwise not delivered successfully to the user within the delay bound of 50 ms. The packet delay is defined based on the 98th percentile of the CDF of all individual users' 98th percentiles of packet delay (i.e., the 98th percentile of the packet delay CDF first determined for each user, and then the 98th percentile of the 666 CHAPTER 12 Performance of IEEE 802. 16m and 3GPP LTE-Advanced TABLE 12-4 VolP Traffic Model Parameters [8] Statistical Probabilistic VolP Model Attribute Distribution Parameters Distribution Active/inactive state Exponential u=1.25 s fx = x > 0 duration A=1/u Probability of state = 0.01, d = 0.99 transition Packet arrival delay jitter Laplacian = 5.11 ms (downlink only) -80ms 80ms TABLE 12-5 Assumptions for VolP Capacity Calculation [6,8,9,10] Parameter Characterization Codec 3GPP AMR12.2 kbps Encoder Frame Length 20 ms Voice Activity Factor (VAF) Payload Active: 33 bytes (octet-aligned mode) Inactive: 7 bytes SID Packet is sent every 160 ms during silence intervals Protocol Overhead with Compressed Header 10 bits + padding (RTP-pre-header) 4 bytes (RTP/UDP/IP) 2 bytes (RLC/security) 16 bits (CRC) CDF that describes the 98th percentiles of the individual user's delay is obtained). VoIP capacity is measured as active users/MHz/cell. It is the minimum of the capa