Two-tier call admission control algorithm in IEEE 802.11 WLAN

• US 20080075050A1
• Filed: 11/30/2006
• Published: 03/27/2008
• Est. Priority Date: 09/22/2006
• Status: Active Grant

• Current Assignee: National Chiao Tung University (Government of The Republic of China)
• Original Assignee: National Chiao Tung University (Government of The Republic of China)
• Inventors: Huang, Ching Yao, Shih, Yuan Hwai
• Granted Patent: US 7,792,028 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

The present invention discloses a two-tier call admission control algorithm in IEEE 802.11 WLAN. The two-tier call admission control algorithm is given to improve the overall system throughput and guarantee the quality of service of every single user in the WLAN.

Claims

1. A two-tier call admission control algorithm for IEEE 802.11 WLAN, wherein the two-tier call admission control algorithm in IEEE 802.11 WLAN is used to admit of the provision of the service request where high quality of service is a key factor, comprising the following step:

to have a single user and the overall system corresponding respectively to a first layer testing and a second layer testing.

2. Two-tier call admission algorithm in accordance with claim 1, wherein the control of the first layer consists of the measurement of a physical layer and the testing of the physical layer to serve as the first layer check.

3. Two-tier call admission algorithm in accordance with claim 1, wherein a plurality of the station platforms that only pass the first layer test are allowed to initiate an associated request to the overall system, and then get into the second layer test.

4. Two-tier call admission algorithm in accordance with claim 1, wherein buffer time is introduced in the second layer test in order to compensate for the TXOP (Transmission Opportunity) variation of the station platforms induced by the status change of the physical layer.

5. Two-tier call admission algorithm in accordance with claim 4, wherein the transmission probability between different modes, which is served as a parameter in the calculation of the buffer time, is defined by a three-dimensional AARF Markov chain described by the following equation:

$\begin{array}{c}{P}_{{\mathrm{down}}_m}=<br><br>P<br><br>\left(m-1|m\right)\\ =<br><br>\frac{P<br><br>\left(m-1\bigcap <br><br>m\right)}{P<br><br>\left(m\right)}\\ =<br><br>\frac{\underset{d=1}{\overset{4}{\sum <br><br>}}<br><br><br><br>\left\{\begin{array}{c}{P}_f^2<br><br>\left(m,\mathrm{SNR}\right)\times <br><br>\left[\underset{k=1}{\overset{T_d-1}{\sum <br><br>}}<br><br><br><br>b<br><br>\left(m,k,d\right)+b<br><br>\left(m,D,d\right)\right]+\\ P_f<br><br>\left(m,\mathrm{SNR}\right)\times <br><br>\left[b<br><br>\left(m,p,d\right)+b<br><br>\left(m,0,d\right)\right]\end{array}\right\}}{\underset{d=1}{\overset{4}{\sum <br><br>}}<br><br><br><br>\left\{\underset{k=0}{\overset{T_d}{\sum <br><br>}}<br><br><br><br>b<br><br>\left(m,k,d\right)+b<br><br>\left(m,P,d\right)+b<br><br>\left(m,D,d\right)\right\}}\end{array}$ $\begin{array}{c}{P}_{{\mathrm{up}}_m}=<br><br>P<br><br>\left(m+1|m\right)\\ =<br><br>\frac{P<br><br>\left(m+1\bigcap <br><br>m\right)}{P<br><br>\left(m\right)}\\ =<br><br>\frac{\underset{d=1}{\overset{4}{\sum <br><br>}}<br><br><br><br>\left\{\begin{array}{c}\begin{array}{c}{P}_s^{10}<br><br>\left(m,\mathrm{SNR}\right)\times <br><br>b<br><br>\left(m,P,d\right)+\\ P_s^{T_d}<br><br>\left(m,\mathrm{SNR}\right)\times <br><br>\left[b<br><br>\left(m,D,d\right)+b<br><br>\left(m,0,d\right)\right]+\end{array}\\ \underset{k=1}{\overset{T_d-1}{\sum <br><br>}}<br><br><br><br>\left(P_s^{T_d-k}<br><br>\left(m,\mathrm{SNR}\right)\times <br><br>b<br><br>\left(m,k,d\right)\right)\end{array}\right\}}{\underset{d=1}{\overset{4}{\sum <br><br>}}<br><br><br><br>\left\{\underset{k=0}{\overset{T_d-1}{\sum <br><br>}}<br><br><br><br>b<br><br>\left(m,k,d\right)+b<br><br>\left(m,P,d\right)+b<br><br>\left(m,D,d\right)\right\}}\end{array}$

where m denotes the present mode of the station platform, b is the state probability, P_s represents the probability of the successful transmission of the packet, P_f represents the probability of the failed transmission of the packet, d denotes the relative three-dimension value, and T_d is the related threshold value.

6. Two-tier call admission algorithm in accordance with claim 4, further comprises a parameter SI (service interval), which is defined by the following equation:

SI=min(DB_i), ∀

i

where DB denotes the delay bound, and i is an integer.

7. Two-tier call admission algorithm in accordance with claim 4, further comprises a parameter G, which denotes the sum of each TXOP and is defined by the following equation:

$G=\underset{i=1}{\overset{k}{\sum <br><br>}}<br><br><br><br>T\times <br><br>\mathrm{OPi},$

where k is an integer.

8. Two-tier call admission algorithm in accordance with claim 4, further comprises a parameter BT (buffer time), which is defined by the following equation:

$\mathrm{BT}=\underset{l=1}{\overset{k}{\sum <br><br>}}<br><br><br><br>N_i\times <br><br>L_i\times <br><br>\left(P_{{\mathrm{down}}_{i,m}}\times <br><br>{\mathrm{\delta <br><br>}}_{{\mathrm{down}}_{i,m}}-P_{{\mathrm{up}}_{i,m}}\times <br><br>{\mathrm{\delta <br><br>}}_{{\mathrm{up}}_{i,m}}\right)+\mathrm{\Delta <br><br>}$

where δ

_down denotes one bit'"'"'s time difference when the mode is decreasing, δ

_up denotes one bit'"'"'s time difference when the mode is increasing, and Δ

denotes the uncertain characteristics in compensating each communication throughput, k is an integer, and N,L are two communication parameters.

9. Two-tier call admission algorithm in accordance with claim 4, further comprises a parameter deadline, which is defined via the following equation:

D_eadline=SI−

BT

10. Two-tier call admission algorithm in accordance with claim 4, further comprises a decision criterion, which is defined via the following equation:

(G>

Deadline)∩

(RD>

N_reject)

where RD denotes the rejection density, and N_reject denotes a prescribed value. If the equation holds, then the overall system rejects any new request for connection. If the equation does not hold, then the overall system consents to new associated requests.