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, each user is allocated 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 different time slot. Forward link frequency new spreading factor for each data rate and reverse link frequency hence the optimal power calculation is done according to the samespreading factor as follows. A synchronous switch <br> Spreading factor(Gi) is responsible for defined as the ratio of bandwidth of the system to the data rate of the time switchingradio frame.[[Image:cdma10.jpg|thumb|center|TDMA]]Mathematically,<br>'''Gi =W / Ri''',where W=system bandwidth which is a constant for a system and Ri= Code Division Multiple Access ===data rate of radio frame.<br>There A power index (gi) is no restriction on time and frequency in calculated from this scheme. All Spreading Factor(Gi) using the users can transmit at all times and at all frequencies. Because users are isolated by codefollowing expression<br>'''gi= (vi / (vi+Gi))''', they can share where vi is minimum QoS for the same carrier frequency, eliminating the frequency reuse problem encountered in other technologiesith session which is a constant.<br> [[Image:cdma11This power index will ascertain the optimal power to be alloted to each service channel(each data rate for different services).jpg|600 px|centre|CDMA]]<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.

A comparative study between From the above three access technologies with respect to time analysis, we observe that when the mobile is sent the optimal power at which it should transmit. It can backtrack and frequency calculate the power index and spreading factor and hence the Data rate is as shown belowchanged 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:cdma12IEEEGurbuz.jpgpdf|600 px|centre|Comparison of cellular access schemesDynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]].

==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:''' In this method Thus, we conclude that by adjusting the direct sequence(input data) which is spread over a limited bandwidth is multiplied with a code or spreading sequence (a pseudorandom sequence) which will spread the input data over the entire bandwidth of the communication channel. The optimal power density is also reduced and is spread over the frequency spectrum and hence is known as spread spectrum method. The modulation part of DSSS is as shown below<br>[[Image:cdma13.jpg]]The modulated signal is transmitted over the channel and all users can receive it but only the user which knows the correct code can only decode the message. This is depicted in the figure below.<br>[[Image:cdma14.jpg]]===Features of CDMA=======Frequency Reuse==== Number of radio channel frequencies we are limited. The concept of frequency reuse is based on assigning actually trying to each cell implement 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 interfererate matching step.

===Dynamic Resource Scheduling(DRS) Algorithm=Soft Handoff==== Handoff means Switching a cellular phone transmission from one 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 another as the Base Station(BS) where they are queued in a mobile user moves into a new cellular areaFIFO. It is so called because The BS determines a spreading factor which allocates the radio link with the previous sectorOrthogonal Varible Spread code(sOVSF) using '''Gi = W / Ri''',where W=system bandwidth which is not broken before a link is established with constant for a new sector; this type system and Ri= data rate of handoff radio frame.<br> The base station calculates a value of power 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 described conveyed to the MS using TPC(Transmission Power Control) bits and a closed loop power control method as "make before break"explained in section 5. In CDMA due to this soft handoff there 6 above is no interruption of call even at performed to obtain the border final value of cell site power at which means more number of customers can transmission should be accommodated automatically increasing done.The method and algorithm to schedule optimal power using Dynamic Resource Scheduling is detailed in the capacity of the cell siteIEEE paper 765366 [[Media:IEEEGurbuz.pdf|Dynamic Resource Scheduling for Variable QoS Traffic in W-CDMA - Ozgur Gurbuz, Henry Owen]].

===Optimal Power Control Algorithm=Multipath Fading==== In The Base Station receives a mobile environment a mobile station will receive one direct signal Pilot Signal from the base Mobile station and multiple signals which are reflected from obstructions like building calculates BER based on Distance,Transmission rate and towers. Each signal would have travelled a different length and would be displaced No of Users in time. Due to this when they are combined at the mobile it will cause interference resulting in poor signal qualityCell. This Ptk is called as fading. This problem is handled in a very good way in CDMA. Here the phase of the multiple signals is modified such the only positive interference(addition) takes place the overall transmitted signal strength increases. A receiver that implements the above principle power which is known as a RAKE receiver as shown in expressed by the figure below<br>[[Image:cdma15.jpg]]====Near Far Problem==== The problem is described by taking an example consider a receiver and two transmitters power control function g (one close to the receiver; the other far awayrt , k ). If both transmitters transmit simultaneously and at equal powers, then due to a function of the inverse square law the receiver will receive more power distance from the nearer transmitter. This makes the farther transmitter voice more difficult mobile to understand. Since one transmissionbase station,'s signal is the other's noise the signal-to-noise ratio 'Ptk= g(SNRrt,k) for the farther transmitter Po''' where Po is much lower. If the nearer transmitter transmits a signal that is orders of magnitude higher than the farther transmitter then the SNR for the farther transmitter may be below detectability and the farther transmitter may just as well not transmit. This effectively jams the communication channel. In CDMA systems this is commonly solved by dynamic output maximum transmission power adjustment of the transmitters. That is the closer transmitters use less The optimum 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.<br>[[Image:cdma16.jpg]]====Power Control:==== As the propagation losses between BS and MS's functions are different according transmitted to individual communication distances, the received levels at the base Mobile station are different from each other when all mobile stations transmit their signals at which calculates the same optimal powerand starts transmitting at that value. Moreover, Thus meeting the received level fluctuates quickly due to fadingrequired QoS parameters. In order to maintain the strength of received signal level at BS, The method and algorithm for optimal power control technique must be employed is detailed in CDMA systems.<br>.the IEEE paper 503476 [[ImageMedia:cdma17IEEEYao.jpg]]<br>Power control can be implemented in two ways : open loop pdf|Optimal power control law for Multi-media - Multi-rate CDMA systems- Shee Yao and closed loop power control<br>Evaggelos Geraniotis[[Image:cdma18.jpg]].

'''Effect of Power Control''' Power control is capable of compensating the fading fluctuation. Received power from all MS are controlled to be equal.　Near-Far problem is mitigated by the power control.[[Image:cdma19.jpg]]==Quality of ServiceResearch Activity (QoSNon Patent) in the Period (1991-2003)==CDMA is being accepted as a third generation system and a specific feature of 3G system is that it offers a radio interface adapted for all kinds of services and combination of services(data,voice,image etc). NOTE: The big issue analysis presented below is of multiplexing of these services which have do not have with respect to the same demands in terms of quality of service(QoS) IEEE Papers published between 1991-2003 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 focus on the coding bits have atleast a code dependent ratio Eb/I(ratio aspect of bit energy to interference). There are several influences that might change system performance(BER) and hence Eb/I ratio, Quality of which the most effective is variation of Bit Rate by a step of '''Rate Matching'''. <br><br>===Rate Matching and QoS===The patent '''EP 1385290 titled Method for balancing Eb/I ratio in a service multiplexing CDMA system Service and a telecommunication system its Management using this method''' targets at this concept of various paramters like Rate matching and introduces an algorithm of 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 BS or MS). The following framework highlights the various steps involved in providing variable QoS, Power control, Variable Spreading Factor etc.

===Power Control, Rate Matching and QoS===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[[Image:Publication_Year. Spreading factor(Gi) is defined as the ratio JPG|center|thumb|500 px|Number of bandwidth publications VS Year of the system to the data rate of the radio frame.publication]]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 power index (gi) is calculated from this Spreading Factor(Gi) using the following expression<br>'''gi= (gi / (gi+Gi))''', where gi is minimum QoS for the ith session which is a constant.<br> This power index will ascertain the optimal power to be alloted to each service channel.<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 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 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 suggests a increase in glove and have the same effect on Eb/I and QoS.The method and algorithm to schedule optimal power is detailed Research activity in the IEEE paper '''Dynamic Resource Scheduling for Variable area of QoS Traffic Management 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 stepyear 1999.[[Media:ieee1.pdf]]

===Power control and QoS===SPEECH transmission is the main service supported by the first two generations of mobile communication systems[[Image:Publishers. However, future systems should be able to handle a wide variety JPG|center|thumb|500 px|Publisher VS number of different services with bit rate requirement ranging from a few kilobits/s to as much as 2 Mb/s. There are many ways to design a CDMA system to support multirate services . One way to do so publications during(1991-2003)]] It is to spread all signals, independent of be noted that the bit rate, to the same bandwidth . This non patent research is done by keeping the chip rate constant. Users transmitting at low bit rate thus have a high processing gain. This allows those users attributed mostly to transmit at a lower power. Therefore, the conventional constant received power scheme is not appropriate universities in such a multirate systemUSA and Asia Pacific. A more sophisticated power control scheme is needed to achieve diverse quality The mention of service (QoS) and rate requirement. One such scheme which explores the relationship between the data rate, the QoS, and the transmit power is presented in the IEEE paper '''Power Control and Rate Management for Wireless Multimedia CDMA Systems Chi Wan Sung, Member, IEEE, and Wing Shing Wong, Senior Member, IEEE.member'''in the above graph indicates the absence of information about the parent department of the Researcher.===Dynamic Resource Scheduling and QoS===Dynamic Resource Scheduling (DRS) has been proposed as an adaptive resource management and QoSprovisioning framework applicable to W[[Image:CDMA_-CDMA systems_3D. Various spreading strategies like Fixed Spreading Gain (FSG), Variable Spreading Gain (VSG) and Multi Code (MC) strategies and their performance is compared in terms JPG|center|thumb|500 px|Graph showing number of power saving, resource allocation and QoS stability in the IEEE paper '''DYNAMIC RESOURCE SCHEDULING STRATEGIES FOR QOS IN W-CDMA publications by Ozgur Gurbuz, Henry Owen.''' VSG-DRS and MC-DRS outperform the FSGpublishers during 1991-DRS for capacity as a result of the statistical multiplexing gain created by adaptive bandwidth usage.2003]]

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 Dynamic Resource scheduling, all with the sole aim of 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"| [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"| [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="center"|-! style="background:lightgrey" | Samir Raiyani|-| '''Email''': [mailto:info@dolcera.com info@dolcera.com]|-| '''Phone''': +1-650-269-7952|}