Changes

== Cellular Communication communication==A cellular mobile communications system uses a large number of low-power wireless transmitters to create cells — the basic geographic service area of a wireless communications system. Variable power levels allow cells to be sized according to the subscriber density and demand within a particular region. As mobile users travel from cell to cell, their conversations are handed off between cells to maintain seamless service. Channels (frequencies) used in one cell can be reused in another cell some distance away. Cells can be added to accommodate growth, creating new cells in unserved areas or overlaying cells in existing areas. [http://www.IEC.org Source[CDMA Basics]]

There are three main entities in cellular communication* Mobile Station (MS): A mobile station consists of 2 entities - equipment In the next sections we discuss the basics for the Patents EP1385290 and SIM cardEP1156616.* Base Transceiver station ==Quality of Service(BTSQoS): A base transceiver station consists of 2 entities - ==CDMA is being accepted as a base transceiver third generation (transmitter and receiver3G) station system and a base station controller. The BTS specific feature of 3G systems is the antenna tower site.* Main Switching centrethat they offer a radio interface adapted for all kinds of services and combination of services (MSCsuch as data, voice, video etc): . The main switching centre big challenge is multiplexing these services which do not have the heart same demands in terms of the network - the central switching office quality of service(QoS) which controls all the base stations and provides connection with landline phones. It performs three main tasks. It:# connects calls from sender to receivercan be represented as BER(bit error rate),# collects details of the calls made and receivedprocessing delay, frame error rate etc. Different QoS will require different channel encoding and# supervises operation interleaving strategies. The demand of BER can be satisfied when the rest coding bits have at least a code dependent ratio Eb/I(ratio of the network componentsbit energy to interference).

== Cellular System Architecture =Need for Rate Matching===Cellular systems are increasing In a system using Multiple Access CDMA technology, the greater the Eb/I ratio the greater is the QoS. Transport channels having different QoS requirement do not have the same need in demand as more users are added to their systemsterms of Eb/I ratio. The amount If all the channels are allocated a fixed Eb/I ratio which corresponds with the maximum required by a transport channel then other channels will have "too" good a Quality of frequency spectrum available for mobile cellular use was limitedService, needlessly causing '''interference and efficient use of resource blocking'''. There are several influences that might change system performance(BER) and hence Eb/I ratio,in accordance with the required frequencies was needed QoS of which the most effective is variation of Bit Rate by a step of '''Rate Matching'''. The standard framework for mobile cellular coveragethe management of QoS in CDMA systems is shown below. In modern cellular telephony, rural and urban regions are divided The following framework highlights the various steps involved in providing variable QoS. The received data from the transport block is classified into areas according to specific provisioning guidelinesdifferent processes based on their QoS. Provisioning for each region Data is planned according split onto various transport channels to an engineering plan that includes cellswhich a CRC code is attached for error correction. Further, clustersall these transport channels are multiplexed on one line by concatenation, frequency reuseinterleaved, segmented and handoversthen rate matched.The rate matching step is performed using the rate matching ratio and puncturing ratio which is received from the sending entity (an exchange of handshaking signals occurs).<br>[[Image:cdma_2_7.jpg|thumb|700px|center|QoS Management in CDMA - Standard Framework]]

==== Cells ==== A cell The rate matching step in above figure is the basic geographic unit of essentially implemented by repetition or puncturing, SIEMENS has proposed an algorithm to ETSI, to obtain a cellular systemnon-integer punture/repetition ratio referenced SM/G2/UMTS-L1/Tdoc428/98 and it is given as follows. Cells are base stations transmitting over small geographic areas that are represented This algorithm is used as hexagonsa standard approach for Rate Matching. [[Image:cdma21.jpg|thumb|700px|center|Rate matching algorithm by SEIMENS]]

==== Clusters ==== A cluster is a group of cells. No channels are reused within a cluster. Normally a cluster has seven cells in it as shown below[[Image:Cdma1.JPG|thumb|center|700 px|CDMA Basics]]

==== Frequency Reuse ====The number of radio channel frequencies is limited. The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area. Cells are assigned a group of channels that is completely different from neighboring cells. The coverage area of cells is called the footprint. This footprint is limited by a boundary so that the same group of channels can be used in different cells that are far enough away from each other so that their frequencies do not interfere[[Media:Cdma_talk.pdf|CDMA basics]]

==== Cell Splitting =QoS Management Algorithms=== As a service area becomes full Quality of users, this approach is used to split a single area into smaller ones. In this way, urban centers Service can be split into as many areas as necessary managed according to provide acceptable service levels in heavy-the varying type of traffic regionsi.e. data, while largervoice, less expensive cells can be used to cover remote rural regionsvideo in the following four ways.# Rate Matching Algorithm# Code Hopping Algorithm# Dynamic Resource Scheduling(DRS) Algorithm# Optimal Power Control Algorithm[[Image:cdma_22.jpg|thumb|600 px|center|QoS Management in CDMA - Analysis restricted till 1999]]

===Rate Matching Algorithm= Handoff ==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# The second rule concerns segmentation of the coded block into the size of the segment produced by segmentation per multiplexing frame# The third rule is about obtaining the size of the oputput block Y from the Input block X according to a rate matching step explained below.<br>The Parameters Ei(Energy per bit),Pi(Max puncture Rate) and Xi(Input data rate) are the characteristic constants of a transport channel both at the Mobile Station(MS) and the Base Station(BS). Initially Ei,Pi and Xi are determined at the Base Station and a maximum possible payload is calculated. This is known as the intermediate size and and a vector of expected is transmitted to the Mobile Station(MS) along with the parameters Ei and Pi. Using the values of Pi,Ei and Xi the mobile will also calculate its output frame size Yi. Then final step is matching this value of Yi with the received vector of Intermediate values Yi and decide the final frame size. The bits are repeated or punctured according to the required Final Frame Size.<br>

==Evolution of Cellular Systems=<span style=[[Image"color:cdma1.jpg|500 px|center]]#C41E3A">Like this report?</span>== Multiple Access Methods =<p align="center"> '''This is only a sample report with brief analysis''' <br>There are predominantly three types of multiple access methods.'''Dolcera can provide a comprehensive report customized to your needs'''</p>{|border="2" cellspacing="0" cellpadding= Frequency Division Multiple Access "4" align="center" "|style="background:lightgrey" align =In this system, each user is allotted a different set of frequencies to operate upon"center" colspan = "3"|'''[mailto:info@dolcera. The uplink(mobile to base station) frequency is different com <span style="color:#0047AB">Buy the customized report from downlink frequency(base station to mobile)Dolcera</span>]''' |-| align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services Patent Analytics Services]|align = "center"| [http://www.dolcera.com/website_prod/services/business-research-services Market Research Services]|align = "center"| [Imagehttp:cdma6//www.jpgdolcera.com/website_prod/tools/patent-dashboard Purchase Patent Dashboard]|thumb-|700pxalign = "center"|[http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/patent-search/patent-landscapes Patent Landscape Services]|align = "center"|[http://www.aidolcera.ucom/website_prod/research-hyogoprocesses Dolcera Processes]|align = "center"| [http://www.acdolcera.jpcom/~thaiwebsite_prod/industries Industry Focus]|-proj|align = "center"| [http:/presen/20051222www.dolcera.com/website_prod/services/ip-Ishikawapatent-analytics-services/patent-search/patent-landscapes Patent Search Services]|align = "center"| [http://www.ppt FDMA]dolcera.com/website_prod/services/ip-patent-analytics-services/alerts-and-updates Patent Alerting Services]|align = "center"| [http://www.dolcera.com/website_prod/tools Dolcera Tools]|-|}<br>=== Time Division Multiple Access Code Hopping Algorithm===In this systemAccording 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 user data rate and hence the optimal power calculation is allocated a different time slotdone according to the spreading factor as follows. Forward link frequency and reverse link frequency <br> Spreading factor(Gi) is defined as the sameratio of bandwidth of the system to the data rate of the radio frame. Mathematically,<br>'''Gi = W / Ri''',where W=system bandwidth which is a constant for a system and Ri= data rate of radio frame.<br>A synchronous switch power index (gi) is responsible calculated from this Spreading Factor(Gi) using the following expression<br>'''gi= (vi / (vi+Gi))''', where vi is minimum QoS for the time switchingith session which is a constant.<br> [[Image:cdma10This power index will ascertain the optimal power to be alloted to each service channel(each data rate for different services).<br> '''Pi = (gi*No*W )/ (Hi*(1-(Sgj)'''<br>where No is AWGN(Additive White Guassian Noise)a constant,<br> Hi is path loss which is dependent on the distance and is a constant for a path,<br> and Sgj is sum of the power index of all the sessions which is constant for all sessions of the radio frame.jpg|thumb|600px|center|TDMA]]

=== Code Division Multiple Access ===There From the above analysis, we observe that when the mobile is no restriction on time and frequency in this scheme. All sent the users can transmit optimal power at all times and at all frequencieswhich it should transmit. Because users are isolated by code, they It can share backtrack and calculate the same carrier frequency, eliminating power index and spreading factor and hence the frequency reuse problem encountered in other technologiesData rate is changed accordingly.This step can be considered to be an equivalent to the Rate Matching Algorithm explained above. The method and algorithm to schedule optimal power is detailed in the IEEE paper 765366 [[ImageMedia:cdma11IEEEGurbuz.jpg|thumb|600 px|centrepdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA- Ozgur Gurbuz, Henry Owen]]<br>.

A comparative study between Thus, we conclude that by adjusting the above three access technologies with respect optimal power we are actually trying to time and frequency is as shown belowimplement a rate matching step.[[Image:cdma12.jpg|thumb|600 px|centre|Comparison of cellular access schemes]]

== Code Division Multiple Access ==The CDMA technology can be implemented in two ways* Direct Sequence Spread Sprectrum - DSSS CDMA* Frequency Hopping - FH CDMA=== Direct Sequence Spread Sprectrum - DSSS CDMA Dynamic Resource Scheduling(DRS) Algorithm=== In this methodThe Mobile Station(MS) performs Matching of Traffic Descriptors such as Peak Cell Rate(PRC), Sustainable Cell Rate(SCR) and obtains the direct sequenceconnection parameters like average cell rate, SIR, Delay from them. These parameters are sent to the Base Station(input dataBS) which is spread over where they are queued in a limited bandwidth is multiplied with FIFO. The BS determines a code or spreading sequence factor which allocates the Orthogonal Varible Spread code(a pseudorandom sequenceOVSF) using '''Gi = W / Ri''',where W=system bandwidth which will spread the input is a constant for a system and Ri= data over the entire bandwidth rate of the communication channelradio frame. <br> The base station calculates a value of power density is also reduced index '''gi= (vi / (vi+Gi))'''and hence Power levels using '''Pi = (gi*No*W )/ (Hi*(1-(Sgj))''', where S stands for sumof, and transmits them to the MS. This information is spread over conveyed to the frequency spectrum MS using TPC(Transmission Power Control) bits and hence is known as spread spectrum a closed loop power control method. The modulation part of DSSS is as shown belowexplained in section 5.[[Image:cdma13.jpg|thumb|600px|center|CDMA Modulation]]The modulated signal 6 above is transmitted over performed to obtain the channel and all users can receive it but only the user final value of power at which knows the correct code can decode the messagetransmission should be done. This The method and algorithm to schedule optimal power using Dynamic Resource Scheduling is depicted detailed in the figure below.IEEE paper 765366 [[ImageMedia:cdma14IEEEGurbuz.jpg|thumb|600px|centerpdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA Demodulation- Ozgur Gurbuz, Henry Owen]].

=== Frequency Reuse Optimal Power Control Algorithm=== The number of radio channel frequencies is limited. The concept of frequency reuse is Base Station receives a Pilot Signal from the Mobile station and calculates BER based on assigning to each cell a group Distance,Transmission rate and No of radio channels used within a small geographic areaUsers in the Cell. Cells are assigned Ptk is the transmitted signal power which is expressed by the power control function g ( rt , k ), a group function of channels that is completely different the distance from neighboring cells. The coverage area of cells the mobile tobase station,'''Ptk= g(rt,k)Po''' where Po is called the footprintmaximum transmission power. This footprint is limited by a boundary so The optimum power functions are transmitted to the Mobile station which calculates the optimal power and starts transmitting at that value. Thus meeting the same group of channels can be used required QoS parameters.The method and algorithm for optimal power control is detailed in different cells that are far enough away from each other so that their frequencies do not interferethe IEEE paper 503476 [[Media:IEEEYao.pdf|Optimal power control law for Multi-media - Multi-rate CDMA systems- Shee Yao and Evaggelos Geraniotis]].

=== Soft Handoff =Research Activity (Non Patent) in the Period (1991-2003)== Handoff means switching a cellular phone transmission from one cell to another as a mobile user moves into a new cellular area. It NOTE: The analysis presented below is so called because the radio link with the previous sector(s) is not broken before a link is established with a new sector; this type of handoff is described as "make before break". In CDMA, due respect to this soft handoff, there is no interruption of call even at the border of a cell site IEEE Papers published between 1991-2003 which means more number focus on the aspect of customers can be accommodatedQuality of Service and its Management using various paramters like Rate matching, automatically increasing the capacity of the cell sitePower control, Variable Spreading Factor etc.

=== Multipath Fading === In a mobile environment, a mobile station will receive one direct signal from the base station and multiple signals which are reflected from obstructions like buildings and towers. Each signal would have travelled a different length and would be displaced in time. Due to this, when they are combined at the mobile handset, it will cause interference resulting in poor signal quality. This is known as ''fading''. This problem is handled in a very good way in CDMA. Here, the phase of the multiple signals is modified such that only positive interference(addition) takes place and the overall signal strength increases. A receiver that implements the above principle is known as a RAKE receiver as shown in the figure below.[[Image:cdma15Publication_Year.jpgJPG|center|thumb|center500 px|600px|RAKE receiverNumber of publications VS Year of publication]]=== Near Far Problem === The problem is best described by taking an example: Consider above analysis suggests a receiver and two transmitters (one close to increase in the receiver; Research activity in the other far away). If both transmitters transmit simultaneously and at equal powers, then due to the inverse square law, the receiver will receive more power from the nearer transmitter. This makes the farther transmitter voice more difficult to understand. Since one transmission's signal is the other's noise the signal-to-noise ratio (SNR) for the farther transmitter is much lower. If the nearer transmitter transmits a signal that is orders area of magnitude higher than QoS Management in the farther transmitter, then the SNR for the farther transmitter may be below detectability and the farther transmitter may just as well not transmityear 1999. This effectively jams the communication channel. In CDMA systems, this is commonly solved by dynamic output power adjustment of the transmitters. That is, the closer transmitters use less power so that the SNR for all transmitters at the receiver is roughly the same. This sometimes can have a noticeable impact on battery life, which can be dramatically different depending on distance from the base station.[[Image:cdma16.jpg|thumb|600px|center|Dynamic output power adjustment for CDMA transmitters]]

====Power Control==== As the propagation losses between BS and MS's are different according to individual communication distances, the received levels at the base station are different from each other when all mobile stations transmit their signals at the same power. Moreover, the received level fluctuates quickly due to fading. In order to maintain the strength of received signal level at BS, power control technique must be employed in CDMA systems.<br>.[[Image:cdma17Publishers.jpg]]<br>Power control can be implemented in two ways : open loop power control and closed loop power control<br>[[Image:cdma18.jpgJPG|center|thumb|500 px|Publisher VS number of publications during(1991-2003)]]

It is to be noted that the non patent research is attributed mostly to universities in USA and Asia Pacific. The mention of '''Effect of Power ControlIEEE member''' Power control is capable in the above graph indicates the absence of compensating information about the fading fluctuation. Received power from all MS are controlled to be equal.　Near-Far problem is mitigated by parent department of the power control.[[Image:cdma19Researcher.jpg]]

==Quality of Service(QoS)==CDMA is being accepted as a third generation (3G) system and a specific feature of 3G systems is that they offer a radio interface adapted for all kinds of services and combination of services (such as data, voice, video etc)[[Image:CDMA_-_3D. The big challenge is multiplexing these services which have do not have the same demands in terms JPG|center|thumb|500 px|Graph showing number of quality of service(QoS) which can be represented as BER(bit error rate), processing delay, frame error rate etc. Different QoS will require different channel encoding and interleaving strategies. The demand of BER can be satisfied when publications by the coding bits have at least a code dependent ratio Eb/I(ratio of bit energy to interference). There are several influences that might change system performance(BER) and hence Eb/I ratio, of which the most effective is variation of Bit Rate by a step of '''Rate Matching'''.publishers during 1991-2003]]

===Rate Matching and QoS=Conclusion==The patent [[http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=EP1385290&F=0 EP1385290]] titled "Method for balancing Eb/I ratio Substantial amount of research has been done in the field of QoS in a service multiplexing CDMA communication system in the year 1998-99 and a telecommunication system using this method" targets this concept has led to the invention of multitude of methodologies ranging from power control to 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). The following framework highlights the various steps involved in providing variable QoS. The received data from the transport block is classified into different processes based on their QoS. Data is split onto various transport channels to which a CRC code is attached for error correction. FurtherDynamic Resource scheduling, all these transport channels are multiplexed on one line by concatenation, interleaved, segmented and then rate matched. The rate matching step is performed using with the rate matching ratio and puncturing ratio which is received from the sending entity.(an exchange sole aim of handshaking signals is occuring)improving QoS.

==<span style="color:#C41E3A">Like this report?</span>==<p align="center"> '''This is only a sample report with brief analysis''' <br>'''Dolcera can provide a comprehensive report customized to your needs'''</p>{|border="2" cellspacing="0" cellpadding="4" align="center" "|style="background:lightgrey" align = "center" colspan = "3"|'''[mailto:info@dolcera.com <span style="color:#0047AB">Buy the customized report from Dolcera</span>]''' |-| align = "center"| [Imagehttp:cdma20//www.jpgdolcera.com/website_prod/services/ip-patent-analytics-services Patent Analytics Services]|align = "center"| [http://www.dolcera.com/website_prod/services/business-research-services Market Research Services]|align = "center"| [http://www.dolcera.com/website_prod/tools/patent-dashboard Purchase Patent Dashboard]|-|align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/patent-search/patent-landscapes Patent Landscape Services]|align = "center"| [http://www.dolcera.com/website_prod/research-processes Dolcera Processes]|align = "center"| [http://www.dolcera.com/website_prod/industries Industry Focus]|-|align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/patent-search/patent-landscapes Patent Search Services]|align = "center"| [http://www.dolcera.com/website_prod/services/ip-patent-analytics-services/alerts-and-updates Patent Alerting Services]|align = "center"| [http://www.dolcera.com/website_prod/tools Dolcera Tools]|-|}<br>==Contact Dolcera==

{| style="border:1px solid #AAA; background:#E9E9E9" align==Power Control, Rate Matching and QoS==="center"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 computes and assigns optimal powers according to the new spreading factor for each radio frame. Spreading factor(Gi) is defined as the ratio of bandwidth of the system to the data rate of the radio frame.Mathematically,<br>'''Gi ! style= W / Ri''',where W=system bandwidth which is a constant for a system and Ri= data rate of radio frame.<br>"background:lightgrey" | Samir RaiyaniA power index (gi) is calculated from this Spreading Factor(Gi) using the following expression<br>|-| '''gi= (vi / (vi+Gi))Email''', where vi is minimum QoS for the ith session which is a constant: [mailto:info@dolcera.<br> This power index will ascertain the optimal power to be alloted to each service channelcom info@dolcera.<br> com]'''Pi = (gi*No*W )/ (Hi*(1|-(Sgj)'''<br>where No is AWGN(Additive White Guassian Noise)a constant,<br> Hi is path loss which is dependent on the distance and is a costant for a path,<br> and Sgj is sum of the power index of all the sessions which is constant for all sessions of the radio frame. <br>From the above analysis, we observe that Bit Rate is inversely proportional to Spreading factor which will inversely effect the power index and hence the optimal power. Therefore, the Bit Rate and Optimal power go hand in glove and have the same effect on Eb/I and QoS.The method and algorithm to schedule optimal power is detailed in the IEEE paper | '''Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA Ozgur Gurbuz, Henry OwenPhone'''. Thus we conclude that by adjusting the optimal power we are actually trying to implement a rate matching step.[[Media:IEEE1.pdf]] ===Power control and QoS===Transmission power of mobile station is proportional to power control law, which is a function of distance from the base station, transmission rates, interference level (number of active users). In this method the Bit Error probability of the multi rate CDMA mobile station is calculated at the Base station using transmission rates of the mobile.The Optimal power control functions are derived based on the Bit error probability at the base station and these power control functions are transmitted to the mobile. The mobile calculates the optimum power using DYNAMIC PROGRAMMING and transmits its data at this power level. It is of interest to note that the optimum power level is related to power index which will determine the spreading gain and hence the overall bit rate. Thus the optimum power level is acheived by transmitting the data at the calculated bit rate.[[Media:IEEE+1-2.pdf]]650-269-7952 ==Conclusion==Substantial amount of research has been done in the field of QoS in CDMA communication system in the year 1998-99 and this has led to the invention of multitude of methodologies ranging from power control to Rate matching and so on with the sole aim of improving QoS.|}