Changes
/* Quality of Service(QoS) */
[[Image:cdma27.jpg|thumb|600px|center|QoS Management in CDMA - Standard Framework]]
The rate matching step in above figure is essentially implemented by repetition or puncturing, SEIMENS SIEMENS has proposed an algorithm to ETSI, to obtain a non-integer punture/repetition ratio referenced SM/G2/UMTS-L1/Tdoc428/98 and it is given as follows. This algorithm is used as a standard approach for Rate Matching.
[[Image:cdma21.jpg|thumb|700px|center|Rate matching algorithm by SEIMENS]]
===QoS Management PathwaysAlgorithms===
Quality of Service can be managed according to the varying type of traffic i.e. data, voice, video in the following four ways.
# Rate Matching PathwayAlgorithm# Code Hopping PathwayAlgorithm# Dynamic Resource Scheduling(DRS) PathwayAlgorithm# Optimal Power Control PathwayAlgorithm
[[Image:cdma23.jpg|thumb|600 px|center|QoS Management in CDMA - Analysis restricted till 1999]]
===Rate Matching PathwayAlgorithm===
The patent [http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=EP1385290&F=0 EP1385290] titled "Method for balancing Eb/I ratio in a service multiplexing CDMA system and a telecommunication system using this method" targets this concept of Rate matching and introduces an algorithm for calculating effective data output bits by a process of repetition or puncturing of the input bits governed by a '''rate matching ratio''' and '''puncturing ratio''' received from the sending entity (can be a BS or MS). As the number of services increases the number of potential combinations will also increase. There arises a need for simple arithmetic procedures to calculate the transport sizes which is done using the following three rules.
# The first rule concerns Channel encoding wherin the transport block is converted into the coded block by a possible relation of the form Y=X/(coding rate)+Ntail
===Code Hopping and QoS pathwayAlgorithm===
According to one of the methods of dynamic power control (Code Hopping) used in W-CDMA technology, the Rate Information (RI) field in the uplink control channel in W-CDMA frame can be used to notify the base station about the variable bit rates (VBR) it wants to send, then the base station assigns a new spreading factor for each data rate and hence the optimal power calculation is done according to the spreading factor as follows.<br> Spreading factor(Gi) is defined as the ratio of bandwidth of the system to the data rate of the radio frame.
Mathematically,<br>
and Sgj is sum of the power index of all the sessions which is constant for all sessions of the radio frame.
From the above analysis, we observe that when the mobile is sent the optimal power at which it should transmit. It can backtrack and calculate the power index and spreading factor and hence the Data rate is changed accordingly. This step can be considered to be an equivalent to the Rate Matching Pathway Algorithm explained above. The method and algorithm to schedule optimal power is detailed in the IEEE paper 765366 [[Media:IEEEGurbuz.pdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]].
Thus, we conclude that by adjusting the optimal power we are actually trying to implement a rate matching step.
===Dynamic Resource Scheduling(DRS) PathwayAlgorithm===
The Mobile Station(MS) performs Matching of Traffic Descriptors such as Peak Cell Rate(PRC),Sustainable Cell Rate(SCR) and obtains the connection parameters like average cell rate, SIR, Delay from them. These parameters are sent to the Base Station(BS) where they are queued in a FIFO. The BS determines a spreading factor which allocates the Orthogonal Varible Spread code(OVSF) using '''Gi = W / Ri''',where W=system bandwidth which is a constant for a system and Ri= data rate of radio frame.<br> The base station calculates a value of power index '''gi= (vi / (vi+Gi))'''and hence Power levels and transmits them to the MS. This information is conveyed to the MS using TPC(Transmission Power Control) bits and a closed loop power control method as explained in section 5.6 above is performed to obtain the final value of power at which transmission should be done.The method and algorithm to schedule optimal power using Dynamic Resource Scheduling is detailed in the IEEE paper 765366 [[Media:IEEEGurbuz.pdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]].
===Optimal Power Control PathwayAlgorithm===
The Base Station receives a Pilot Signal from the Mobile station and calculates BER based on Distance,Transmission rate and No of Users in the Cell. Ptk is the transmitted signal power which is expressed by the power control function g ( rt , k ), a function of the distance from the mobile to
base station,
Anonymous user
