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Інфокомунікації – сучасність та майбутнє”

Інфокомунікації – сучасність та майбутнє”




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THE OPTIMAL SOLUTION FOR WIMAX AND WI-FI INTERWORKING



Abstract. The problem of interworking of both WiMAX and Wi-Fi networks will be discussed in this report. Will be proposed and overviewed the optimal solution for deploying WiMAX/Wi-Fi network.

Both WiMAX and WiFi provide wireless broadband connectivity, they have been optimized for different usage models: WiFi for very high-speed indoor WLAN connectivity and WiMAX for high-speed Wireless WAN (WWAN) connectivity. By combining WiMAX and WiFi technologies, service providers can offer their subscribers a more complete suite of broadband services in more places.

If we look at Wi-Fi (Figure 1) and WiMAX (Figure 2) networks diagram we see that there are nodes similar to both networks (AAA, Accounting Center, Billing System). But the different switching systems (SS) provide inability to connect Wi-Fi access points (AP) directly to WiMAX switching system. Thus we can make combination of interworking between SS of networks, AAA, Accounting Center and Billing System.

Deploying both WiMAX and Wi-Fi network we can use several methods of merging its architecture. The basic criteria for construction of such network will be the quantity of used equipment.


Methods and models of WiMAX/Wi-Fi Interworking

Compared with independent networking, network convergence can be of benefit for both end users and operators. The user hopes to use the same account number, password, get the same account bill, extend the existing services to a new system, and be granted seamless service continuity between different systems. The unified bill, account and password make account management easier for the user. Seamless service continuity improves user's service experience.

Figure 1 – Wi-Fi basic network diagram



Figure 2 – WiMAX basic network diagram

WiMAX and Wi-Fi interworking scenarios can be divided into the following three types:


  • Common billing and customer care

  • WiMAX-based access control and billing

  • Service continuity


Interworking solution 1 - common billing and accounting

In this solution (Figure 3), WiMAX and Wi-Fi networks share the same accounting and billing systems; so, users only need to open one account. They will receive one bill for usage charges for both WiMAX and Wi-Fi services.

The two networks are parallel to each other and independent. They are different in access control, data routing, support for mobility, billing methods and security mechanisms.

Benefits:

  • Easy to implement – need to upgrade only account center and billing system;

Drawbacks:

Each network uses its own network access identifier (NAI) as Subscriber Terminal IDs (ST).

Interworking solution 2 - shared authentication

In this solution (Figure 4), the Wi-Fi network is subordinate to the WiMAX network. The Authentication, Authorization and Accounting (AAA), associated with Wi-Fi users, are provided by the WiMAX network elements. The Wi-Fi user billing information is collected at the Accounting Gateway (AGW) and reported to the billing system of the WiMAX network.



Figure 3 – WiMAX and Wi-Fi common billing and accounting system



Figure 4 – WiMAX and Wi-Fi shared authentication (AAA)

Benefits:


  • Relatively easy to implement;

  • Both networks uses one NAI for ST identification;

Drawbacks:

  • Each network provide access to the Internet directly through its own switching systems;

  • Wi-Fi network must support Extensible Authentication Protocol (EAP) based authentication;


Interworking solution 3 - service continuity

This solution (Figure 5) allows subscribers to access the IP services provided by the WiMAX system through the Wi-Fi network.

The Wi-Fi and WiMAX networks share AAA and Home Agent (HA). To enable seamless handover between the two networks, the HA, as the anchor point, needs to maintain the IP address of the dual-mode Wi-Fi/WiMAX terminal. During the switching, the dual-mode terminal keeps two connections with the HA; before the new connection is set up, data are transferred between the HA and the terminal through the old link; and after the new connection is established, data are transferred through the new link while the old link is disabled.

Such solution needs require to upgrade WiMAX and Wi-Fi interworking functions from the WiMAX side.

Figure 5 – WiMAX and Wi-Fi service continuity

Benefits:


  • Wi-Fi network access to the Internet through the WiMAX one;

  • Both networks uses one NAI for ST identification;

  • Most of the upgrades are from software side;

Drawbacks:

  • Relatively difficult to implement;

  • Wi-Fi network must support Extensible Authentication Protocol (EAP) based authentication;


Optimal solution choice

If speak about the construction of combined Wi-Fi and WiMAX network the service continuity solution is more reliable and cost efficient. For accounting, billing and authentication we will use common servers that will be provided by WiMAX network elements. Wi-Fi network will provide connection to the Internet through the WiMAX switching system. This solution provides the less quantity of equipment and only software upgrade from the WiMAX side. However only Wi-Fi EAP supported equipment can be used.


List of literature:

  1. WiMAX and WiFi Together: Deployment Models and User Scenarios, Co-authored by Motorola and Intel

  2. WiMAX Forum® Network Interworking Specification, WMF-T37-010-R016v01

  3. http://wwwen.zte.com.cn/endata/magazine/ztetechnologies/2008year/no6/articles/200806/t20080627_162039.html


УДК 621.391

Tropanets T.I.,

ONAT after A.S. Popov

nyutsa@mail.ru
MATHEMATICAL MODEL FOR THE LTE/SAE NETWORK TRAFFIC ENGINEERING
Abstract. This paper introduces mathematical method of the intensity and throughput traffic calculation in the LTE/SAE network. Such that, in 4G networks QoS has to be provided for voice as well as data, it has to be considered in the traffic engineering. This methodology allows to define the traffic, transmitted in the LTE/SAE technology network, considering subscriber mobility type and nine traffic priorities.

3GPP LTE/SAE is a next-generation radio access system designed to support the future end-users requirements. The motivation for technological evolution in mobile communication comes from the globalization of markets and increased vendor competence.

The increased use of mobile services such as high-speed internet access, Multimedia Online Gaming (MMOG), Mobile TV, Web 2.0, wireless DSL and voice substitution contribute huge traffic in the networks. The challenge for next-generation wireless networks is to provide wireless broadband at a better cost and performance, while maintaining seamless mobility, service control and Quality of Service (QoS) provisioning [1].

In 1G networks and 2G networks such as GSM and CDMA there was only one aspect of QoS and it is voice. Providing quality speech was the major concern. Now in 3G and 4G networks QoS has to be provided for voice as well as data. Still priority is given for voice services as they are considered as the primary service (Table 1). They are very delay sensitive and require real - time service. Data services are comprised of text and multimedia. These services are less delay sensitive but expect better throughput and less or no loss rate.

This is needed to be taken in to account in the process of the throughput calculation. Such that there was no traffic priority division in the case of the previous technologies, now it’s a problem in the LTE/SAE traffic engineering, which needs a solution.

To define the traffic, transmitted in the LTE/SAE technology network, the data of the existed traffic has to be analyzed and the subscriber mobility type, his geographical situation, terminal class and the service type has be considered also.

Suppose the investigated network section is from UE to PDN GW. The next proposed mathematical model for the LTE/SAE traffic engineering takes to account the nine traffic priorities. It will help to get the correct traffic intensity and throughput calculation resalts.

Firstly, it is needed to classify the services according to the TS 23.203 Release 9 31 V9.4.0 (Table 1). Also it is necessary to classify all users according to their mobility (motionless subscribers, pedestrians and subscribers in the car).


Table 1 – LTE QoS-based Data Flow Specifications (QCI)

QCI

Bearer type

Application Example

Packet Delay

Packet Loss

Priority

1




Conversational VoIP

100 ms

10-2

2

2




Conversational Video

(Live Streaming)



150 ms

10-3

4

3




Non-Conversational Video

(Buffered Streaming)



300 ms

10-6

5

4




Real-time gaming

50 ms

10-3

3

5




IMS Signaling

100 ms

10-6

1

6




Voice, Video, Interactive Games

100 ms

10-3

7

7




Video (Buffered Streaming),

TCP apps (web, email, ftp)

Platinum vs. gold user

300 ms

10-6


6

8




8

9




9

Next step is the calculation of the specific packet rates for all group of services in uplink and downlink:

 [pack/s],  [pack/s], (1)
where RDL and RUL are the max bitrates for each group of services in downlink and uplink correspondently;

n is referred to the payload volume transported in packets.

Then it is necessary to calculate the burstiness coefficient for every group of service in uplink and downlink:

 ,  , (2)

where Rav UL and Rav DL are the average bitrates bitrates for each group of services in downlink and uplink correspondently;

Rmin UL and Rmin DL are the minimum bitrates for each group of services in downlink and uplink correspondently.

After this calculate the traffic intensities created by LTE/SAE users of 9 groups of services, it classified according to the table 1:


=  [E], (3)

=  [E],

……………………………………………….

=  [E],


where Nmls, Np, and Nsc are the quantity of the motionless pedestrians and subscribers in the car correspondently;

ymls, yp and ysc are the specific traffic intensity of the motionless pedestrians and subscribers in the car correspondently.

Next step is the calculation of the packets rates for every group of services in uplink and downlink:

 [pack/s], (4)

[pack/s],

……………………………………

 [pack/s],

[pack/s],


where k refers to the amount of services available to subscribers.

Then it is possible to calculate the total intensity of LTE/SAE arrivals for every group of services in UL and DL:



....................................................................................



Now we need to calculate the dispersion of packets transmission for every group of services in UL and DL:



…………………………….............................................................……………………(()).



Next step is the calculation of the square root values of dispersion for every group of services:

;  [pack/s], (7)

……………………………………..

.

Next we calculate the total traffic intensity for every group of services:





(8)

………………………………………………



Calculate traffic intensity for every group of services expressed in packets:

 , (9)

…………………….



where n is refer to the length of packets.

Finely, calculation of the total Throughput for LTE/SAE traffic that transits an eNodeB:

. . .  . (10)

Tanks to this methodology it is simple to calculate the traffic intensity and traffic throughput for LTE/SAE network taken to account all features of this technology. This variant of throughput calculation allows to define the traffic, transmitted in the LTE/SAE technology network, considering subscriber mobility type and nine traffic priorities.
List of literature:

1. 3GPP TS 23.203 V8.9.0 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Policy and charging control architecture (Release 8), 2010.

2. "Long Term Evolution (LTE):A Technical Overview." Motorola, Inc., 2007.

3. Тихвинский В.О., Терентьев С.В., Юрчук А.Б. Сети мобильной связи LTE: технологии и архітектура. – М.: Эко-Трендз, 2010 – 284с.




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  • Methods and models of WiMAX/Wi-Fi Interworking
  • Interworking solution 1 - common billing and accounting
  • Interworking solution 2 - shared authentication
  • Interworking solution 3 - service continuity
  • Optimal solution choice
  • УДК 621.391