**2.2.2 Analytical modeling**

Throughput modeling follows similar patterns as that of DBAM. Only the order of bandwidth allocation shall change. Delay modeling is explained in this section. The notations used for delay modeling are given in Table 7.


Table 7. Delay modeling parameters.

412 Wireless Communications and Networks – Recent Advances

**eDBAM Method 6** 

High-priority RTPS

Regular priority RTPS

High-priority nRTPS

Regular priority nRTPS

High-priority BE

Regular priority BE

Low-priority RTPS

Low-priority nRTPS

Low-priority BE

In eDBAM (for example Method 2), low priority service class of high priority user (ex: Low-Priority BE) can be allocated bandwidth ahead of high-priority service class of regular/low-priority user (Regular/Low priority nRTPS). This out of turn allocation of bandwidth improves the throughput for even low priority service class (BE) for high-

Implementation of eDBAM is similar to DBAM. The AAA server shall maintain a mapping of MAC address to the priority value associated with the MAC address. When a MS sends RNG-REQ to BS, BS shall obtain the priority value associated with the MS and allocated bandwidth based on one of the seven methods proposed for eDBAM. BS does not switch between the seven different methods of eDBAM. Each BS shall implement one of the seven

Throughput modeling follows similar patterns as that of DBAM. Only the order of bandwidth allocation shall change. Delay modeling is explained in this section. The

**eDBAM Method 7** 

High-priority RTPS

Regular priority RTPS

Low-priority RTPS

High-priority nRTPS

Regular priority nRTPS

High-priority BE

Regular priority BE

Low-priority nRTPS

Low-priority BE

**eDBAM Method 5** 

High-priority RTPS

Regular priority RTPS

High-priority nRTPS

Regular priority nRTPS

Low-priority RTPS

Low-priority nRTPS

High-priority BE

Regular priority BE

Low-priority BE

methods and stick to that method throughout its operation.

notations used for delay modeling are given in Table 7.

**eDBAM Method 4** 

High-priority RTPS

High-priority nRTPS

Regular priority RTPS

Low-priority RTPS

High-priority BE

Regular priority nRTPS

Low-priority nRTPS

Regular priority BE

Low-priority BE

priority users.

**2.2.1 Implementation** 

**2.2.2 Analytical modeling** 

Table 6. Method 4 to Method 7 of eDBAM.

For BE packets, Packet arrivals are assumed to have a Poisson arrival.

$$P\_n(t) = \frac{(\lambda t)^n}{n!} e^{-\lambda t} \tag{7}$$

We know that, Service Utilization = Mean arrival rate / Mean service rate. i.e.

$$
\rho = \frac{\lambda}{\mu} \tag{8}
$$

For BE traffic (exponential distribution), mean number of packets for a service flow for a particular-SS is given in (9)

$$\text{L} = \frac{\rho}{1 - \rho} \tag{9}$$

Queuing delay for a service flow for a particular SS is given in (10)

$$\mathcal{W} = \frac{L}{\lambda} = \frac{\frac{\rho}{1-\rho}}{\lambda} \tag{10}$$

For RTPS and nRTPS we assume constant arrival pattern. So mean number of packets for a service flow for a particular SS is given in (11)

$$L = \frac{\rho(2-\rho)}{2(1-\rho)}\tag{11}$$

Hence the queuing delay for packets that have constant arrival pattern is:

$$\mathcal{W} = \frac{L}{\lambda} = \frac{\frac{\rho(2-\rho)}{2(1-\rho)}}{\lambda} \tag{12}$$

#### **2.2.3 Simulation of eDBAM**

Simulation was carried out using NS 2.29. LWX was used to simulate wimax on top of ns2. Simulations were carried out for method-2 for eDBAM. Simulation parameters used, are given in Table-8


Table 8. Simulation parameters for eDBAM.

Simulation setup was done such that at any given time the network consists of 1/3rd Highpriority SS, 1/3rd Regular-SS and 1/3rd low-priority SS. Each SS is assumed to have RTPS, nRTPS and BE traffic. Downlink ftp traffic at 1 Mbps was introduced.

#### **2.2.3.1 Throughput results**

Simulation was done to compare the throughput for High-Priority, Regular and Low-Priority BE traffic. Fig. 6 shows the simulation results. A comparison with theoretical results is also provided.

Fig. 6. Throughput for BE traffic for the three different types of user.

From fig. 6 we see that as the number of SS in the network increases, the throughput form Low-priority BE drops. Subsequently the throughput reduces for regular BE and finally the throughput for High-priority BE. Since method-2 prioritized high-priority BE ahead of Regular nRTPS and Low-priority nRTPS, simulations were carried out for the service flow. Results of simulation are shown in Fig.7.

Fig. 7. Throughput for High Priority BE v/s Regular nRTPS v/s Low priority nRTPS.

### **2.2.3.2 Delay results**

414 Wireless Communications and Networks – Recent Advances

Simulation setup was done such that at any given time the network consists of 1/3rd Highpriority SS, 1/3rd Regular-SS and 1/3rd low-priority SS. Each SS is assumed to have RTPS,

Simulation was done to compare the throughput for High-Priority, Regular and Low-Priority BE traffic. Fig. 6 shows the simulation results. A comparison with theoretical results

> High Priority BE Regular BE Low Priority BE

Theoretical High Priority BE Theoretical Regular BE Theoretical Low Priority BE

0 5 10 15 20 25 **Number of SS**

From fig. 6 we see that as the number of SS in the network increases, the throughput form Low-priority BE drops. Subsequently the throughput reduces for regular BE and finally the throughput for High-priority BE. Since method-2 prioritized high-priority BE ahead of Regular nRTPS and Low-priority nRTPS, simulations were carried out for the service flow.

nRTPS and BE traffic. Downlink ftp traffic at 1 Mbps was introduced.

Data rate 10 Mbps OFDMA Frame Duration 5 ms OFDMA symbol time 100.94 μs RTPS data arrival rate 333 Kbps nRTPS data arrival rate 333 Kbps BE data arrival rate 333 Kbps

Table 8. Simulation parameters for eDBAM.

Fig. 6. Throughput for BE traffic for the three different types of user.

**Throughput (in Kbps)**

Results of simulation are shown in Fig.7.

**2.2.3.1 Throughput results** 

is also provided.

**Parameter Value**

Simulations were carried out to find the delay incurred by the service flows. Fig. 8 shows the delay for High-Priority BE, Regular BE and Low-Priority BE.

Fig. 8. Delay for High-Priority BE v/s Regular BE v/s Low-Priority BE.

Packet delay was measured for High-Priority BE, Regular nRTPS and Low-Priority nRTPS. Results of simulation are shown in Fig. 9.

Fig. 9. Delay Results for High Priority BE v/s Regular nRTPS v/s Low Priority nRTPS.

From Fig. 8 and Fig. 9 we see that using eBBAM, packets from high-priority SS are subjected to lesser delay compared to regular and low-priority SS.

#### **2.2.3.3 DBAM v/s eDBAM**

Simulations were done to compare the throughput and delay for DBAM and eDBAM. Fig. 10 shows the throughput comparision for DBAM and eDBAM. We consider method-2 for eDBAM.

From Fig. 10 we observe that the throughput for DBAM drops down much before eDBAM. This is because in case of eDBAM, high-priority BE is allotted bandwidth ahead of regular nRTPS and low-priority nRTPS. Figure 11 shows the simuation results for delay. Again eDBAM fairs better than DBAM.

Packet delay was measured for High-Priority BE, Regular nRTPS and Low-Priority nRTPS.

High Priority BE Regular nRTPS Low Priority nRTPS

0 5 10 15 20 25 **Number of SS**

Fig. 9. Delay Results for High Priority BE v/s Regular nRTPS v/s Low Priority nRTPS.

From Fig. 8 and Fig. 9 we see that using eBBAM, packets from high-priority SS are subjected

Simulations were done to compare the throughput and delay for DBAM and eDBAM. Fig. 10 shows the throughput comparision for DBAM and eDBAM. We consider method-2 for

From Fig. 10 we observe that the throughput for DBAM drops down much before eDBAM. This is because in case of eDBAM, high-priority BE is allotted bandwidth ahead of regular nRTPS and low-priority nRTPS. Figure 11 shows the simuation results for delay. Again

Results of simulation are shown in Fig. 9.


0

to lesser delay compared to regular and low-priority SS.

**2.2.3.3 DBAM v/s eDBAM** 

eDBAM fairs better than DBAM.

eDBAM.

500

1000

1500

**Delay (in msec)**

2000

2500

3000

3500

Fig. 10. Throughput comparison for eDBAM and DBAM for high priority BE.

Fig. 11. Delay results for eDBAM and DBAM for High Priority BE.
