MXPA06005177A - Hybrid tdm/ofdm/cdm reverse link transmission - Google Patents

Abstract

A communication system includes a plurality of access terminals, and an access network. The access network schedules a transmission of data in a time interval from one of the access terminals. The access network selects a multiple access transmission mode from a plurality of multiple access transmission modes, and broadcasts the selected multiple access transmission mode to the access terminals. The selected mode may include a mode in which data is code-division-multiplexed during the time interval, and modes in which data is code-division-multiplexed during a first portion of the time interval, and data is either time-division-multiplexed or orthogonal-frequency-division-multiplexed during a second portion of the time interval.

Description

TRANSMISSION OF RETURN LINK TDM / OFDM / HYBRID CDM FIELD OF THE INVENTION The present invention relates to the transmission of data in a wired or wireless communication system.

BACKGROUND OF THE INVENTION Wireless communication systems are constituted by elements of a network in communication with mobile devices. The communication link of the network, such as from a Base Station (BS) to a mobile device, such as a Mobile Station (MS), is referred to as the One Way Link (FL). The communication link of the mobile device to the network element is referred to as a Return Link (RL). To increase the capacity, and therefore the income for the bearer, there is a need to optimize the resources for the FL and the RL.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a conceptual block diagram of a communication system capable of providing data transmission over back links or FLs. Figure 2 illustrates an FL waveform.

Figure 3 illustrates a method for communicating power control commands and packet delivery orders on a return power control channel. Figures 4A-4C illustrate the architecture for generating signals transmitted on an RL. Figure 5A illustrates a waveform of RL over a time interval, in a mode in which air channel bursts are transmitted at the end of each half-slot. Figure 5B illustrates a waveform of RL over a time interval, in a mode in which the Return Rate Indicator (RRI) channel and the Return Traffic Channel, covered by unique Walsh codes, are transmitted concurrently. Figure 5C illustrates a waveform of RL, over a time interval, in a mode in which the air channels and the return Traffic Channel are transmitted using Time Division Multiplexing (TDM) techniques. Figure 6 illustrates a data transmission by the RL. Figure 7 illustrates a retransmission of data by the RL. Figure 8 illustrates a subscriber station.

Figure 9 illustrates a controller and an access terminal. Figure 10 is a transmission where mode parameters can be changed by subframe. Figures HA and 11B illustrate a waveform of RL on a subframe, in a transmission mode that is CDM within the entire time interval ("mode 1"). Figures 12A and 12B illustrate an RL waveform over a subframe, in a hybrid transmission mode where the CDM and TDM / OFDM modes are multiplexed by time division within a time interval ("mode 2"). Figures 13A and 13B illustrate an RL waveform over a subframe in a hybrid transmission mode that is a TDM where the CDM and TDM / OFDM modes are multiplexed by time division within a time interval, with a ratio of 1: 3 ("mode 3"). Figure 14 illustrates a request packet format, in a mode that allows scheduled resource allocation control for MAC flows in the ATs. Figure 15 illustrates the structure of a Packet Transfer (PG) channel.

DETAILED DESCRIPTION OF THE INVENTION Communication systems have been developed to allow the transmission of information signals from a station of origin to a physically different destination station. In the transmission of an information signal of the originating station on a communication channel, the information signal is first converted into a suitable form for its efficient transmission on the communication channel. The conversion, or modulation, of the information signal involves varying a parameter of a carrier wave in accordance with the information signal, such that the spectrum of the resulting modulated carrier wave is confined within the bandwidth of the channel. communication. At the destination station, the original information signal is reconstructed from the modulated carrier wave received on the communication channel. In general, that reconstruction is achieved using an inverse of the modulation process used by the station of origin. There is also a need to add flexibility to a system to support multiple modulation techniques. There is a need to improve performance in a communication system. The modulation also facilitates multiple access, ie the simultaneous transmission and / or reception, of several signals on a common communication channel. Multiple access communication systems often include a plurality of remote subscriber units that require intermittent access of relatively short duration instead of continuous access to the common communication channel. Multiple methods of multiple access are known in the art, such as Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA). Another type of multiple access technique is a Code Division Multiple Access Extended Spectrum (CDMA) system conforming to the "Mobile Station Compatibility Standard-TIA / EIA / IS-95 Base Station for Extended Spectrum Cell System. Broadband, Dual Mode ", hereinafter referred to as the IS-95 standard. The use of CDMA techniques in a multiple access communication system is described in U.S. Patent No. 4,901,307, entitled "EXTENDED SPECTRUM MULTI ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS", and U.S. Patent No. 5,103,459, entitled "SYSTEM AND METHOD TO GENERATE FORMS OF WAVE IN A CDMA CELLULAR TELEPHONE SYSTEM", both granted to the beneficiary of this. A multiple access communication system can be wireless or wired and can carry voice traffic and / or data traffic. An example of a communication system that transports voice and data traffic is a system according to the IS-95 standard, which specifies the transmission of voice and data traffic over a communication channel. A method for transmitting data in fixed-size code channel frames is described in detail in U.S. Patent No. 5,504,773, entitled "METHOD AND DEVICE FOR FORMATING DATA FOR TRANSMISSION", granted to the beneficiary hereof. According to the IS-95 standard, data traffic or voice traffic is distributed in code channel boxes that are 20 milliseconds wide with data rates as high as 14.4 Kbps. communication transporting voice and data traffic comprise the communication systems that conform to the "3rd Generation Society Project" (3GPP), incorporated in a set of documents including Documents Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (The W-CDMA standard), or "Physical Layer Standard TR-5.5 for Extended Spectrum Systems cdma2000" (The IS-2000 standard). The term base station is an entity of the access network, with which the subscriber stations communicate. With reference to the IS-856 standard, the base station is also referred to as an access point. Cell refers to the base station or a geographic coverage area served by a base station, depending on the context in which the term has been used. A sector is a partition of a base station, which serves a partition of a geographic area served by the base station. The term "subscriber station" is used herein with the meaning of the entity with which an access network is communicated. With reference to the IS-856 standard, the subscriber station is also referred to as an access terminal. The subscriber station can be mobile or stationary. A subscriber station can be any data device that communicates through a wireless channel or through a wired channel, for example fiber optic or coaxial cables. A subscriber station may also be any of a number of device types, including, but not limited to a PC card, compact flash memory, external or internal modem, or cordless or wired telephone. A subscriber station that is in the process of establishing an active connection of the traffic channel with a base station is said to be in a state of establishment of the connection. A subscriber station that has established an active connection of the traffic channel to a base station is called an active subscriber station, and is said to be in a traffic state. The term "access network" is a collection of at least one base station (BS) and one or more base station controllers. The access network transports information signals between multiple subscriber stations. The access network can also be connected to additional networks outside the access network, such as a corporate intranet or the Internet, and can carry information signals between each base station and those external networks. In the multiple access wireless communication system described above, communications between users are conducted through one or more base stations. The term user refers to both animated and inanimate entities. A first user in a subscriber station or wireless subscriber communicates with a second user on a second subscriber station or wireless subscriber carrying information signals S on an RL to a base station. The base station receives the information signal and carries the information signal on an FL to the second subscriber station. If the second subscriber station is not in the area served by the base station, the base station routes the data to another base station, in whose service area the second subscriber station is located. The second base station then carries the information signal on an FL to the second subscriber station. As discussed here above, the FL refers to transmissions from a base station to a wireless subscriber station and the RL refers to transmissions from a wireless subscriber station to a base station. Similarly, the communication can be conducted between the first user on a wireless subscriber station and a second user on a ground station. A base station receives the data of the first user on the wireless subscriber station on an RL, and routes the data through a Public Switched Telephony Network (PSTN) to the second user on a ground station. In many communication systems, for example, send IS-95, -CDMA, and IS-2000, the FL and the RL are separate assigned frequencies. The study of voice only services and data traffic services only revealed some substantial differences between the two types of service. One difference is related to the delay in the delivery of information content. Voice traffic services impose rigorous and fixed delay requirements.

Typically, a total unidirectional delay of a predetermined amount of voice traffic information, referred to as a local frequency frame, must be less than 100 ms. In contrast, the delay of the total unidirectional data traffic may be a variable parameter, used to optimize the efficiency of the data traffic services provided by the communication system. For example, multiuser diversity may be used, data transmission delayed until more favorable conditions, more efficient error correction coding techniques, which require delays significantly greater than the delays that can be tolerated by data services. voice traffic, and other techniques. An example of an efficient coding scheme for data is disclosed in U.S. Patent Application Serial No. 08 / 743,688, entitled "FLEXIBLE DECISION OUTPUT DECODER FOR DECODING CONVOLUTIONALLY CODED CODE WORDS", filed on November 6, 1996, now U.S. Patent No. 5,933,462, issued August 3, 1999, granted to the beneficiary hereof. Another significant difference between voice traffic services and data traffic services is that the former require a fixed and common Degree of Service (GOS) for all users. Typically, for digital communication systems that provide voice traffic services, this requirement results in a fixed and equal transmission speed for all users and a maximum tolerable value for the error percentages of voice frequency frames. In contrast, the GOS for data services may be different from user to user, and may be a variable parameter, whose optimization increases the overall efficiency of the communication system that provides data traffic services. The GOS of a communication system providing data traffic service is typically defined as the total delay incurred in transferring a predetermined amount of data traffic information, which may comprise, for example, a packet of data. data. The term package is a group of bits, including data (payload) and control elements, arranged in a specific format. The control elements comprise, for example, a preamble, a quality metric, and others known to a person skilled in the art. The quality metric comprises, for example, a Cyclic Redundancy Check (CRC), a parity bit, and others known to a person skilled in the art. Another significant difference between voice traffic services and data traffic services is that the former requires a reliable communication link. When a subscriber station or subscriber, communicating voice traffic with a first base station, moves to the edge of the cell served by the first base station, the subscriber station enters a region of overlap with another cell served by a second station. base. The subscriber station in that region establishes a voice traffic communication with the second base station while maintaining a voice traffic communication with the first base station. During that simultaneous communication, the subscriber station receives a signal containing identical information from the two base stations. Likewise, both base stations also receive signals that contain information from the subscriber station. That simultaneous communication is known as imperceptible transfer. When the subscriber station eventually leaves the cell served by the first base station, and interrupts the voice traffic communication with the first base station, the subscriber station continues in the voice traffic communication with the second base station. Because the imperceptible transfer is a "set before interrupting" mechanism, the imperceptible transfer minimizes the probability of interrupted calls. A method and system for providing communication with a subscriber station through more than one base station during the imperceptible transfer process is described in U.S. Patent No. 5, 267,261, entitled "IMPERCEPTIBLE MOBILE ASSISTED TRANSFER IN A CDMA CELLULAR TELEPHONE SYSTEM", granted to the beneficiary hereof. The imperceptible transfer is a similar process whereby communication occurs over at least two sectors of a multisector base station. The imperceptible transfer process is described in detail in U.S. Patent Application Serial No. 08 / 763,498, entitled "METHOD AND APPARATUS FOR TRANSFER BETWEEN SECTORS OF A COMMON BASE STATION", filed on December 11, 1996, now Patent. US No. 5,933,787 issued August 3, 1999, granted to the beneficiary hereof. In this way, both imperceptible and more imperceptible transfers for voice services result in redundant transmissions of two or more base stations to improve reliability. This additional reliability is not so important for data traffic communications because data packets received in error can be retransmitted. The important parameters for the data services are the transmission delay required to transfer a data packet and the average total speed of the data traffic communication system. The transmission delay does not have the same impact on data communication as on voice communication, but the transmission delay is an important metric for measuring the quality of the data communication system. The average total speed is a measure of the efficiency of the data transmission capacity of the communication system. Due to the requirement of a relaxed transmission delay, the transmission power and the resources used to support the imperceptible transfer on the FL can be used for the transmission of additional data, thereby increasing the average total speed by increasing efficiency. The situation is different about the RL. Several base stations can receive the signal transmitted by a subscriber station. Because the retransmission of packets from a subscriber station requires additional power from a limited power source (a battery), it can be efficient to support imperceptible transfer over the RL by allocating resources to several base stations to receive and process the data packets transmitted from the subscriber station. That use of imperceptible transfer increases the coverage capacity and RL as discussed in an article by Andrew J. Viterbi and Klein S. Gilhousen: "Soft Handoff Increases CDMA coverage and Increases RL Capacity," IEEE Journal on Selected Areas in Communications, Vol. 12, No. 8, October 1994. The term imperceptible transfer is a communication between a subscriber station and two or more sectors, where each sector belongs to a different cell. In the context of the IS-95 standard, the communication of the RL is received by both sectors, and the communication of the FL is transported simultaneously on the FLs of two or more sectors. In the context of the IS-856 standard, the transmission of data over the FL is not carried out simultaneously between one of the two or more sectors and the access terminal. Additionally, a more imperceptible transfer can be used for this purpose. The most imperceptible transfer term is a communication between a subscriber station and two or more sectors, where each sector belongs to the same cell. In the context of the IS-95 standard, the communication of the RL received by both sectors and the communication of the FL is transported simultaneously on the FLs of one of the two or more sectors. In the context of the IS-856 standard, the transmission of data over the FL is not carried out simultaneously between one of the two or more sectors and the access terminal. It is well known that the quality and effectiveness of the data transfer in a wireless communication system depends on the condition of a communication channel between a source terminal and a destination terminal. That condition, expressed as, for example, a Signal Ratio to Interference and Noise (SINR), is affected by several factors, for example, a path loss and the variation of the path loss of a subscriber station within an area of coverage of a base station, interference of other subscriber stations of both the same cell and another cell, interference of other base stations, and other factors known to one skilled in the art. To maintain a certain level of service under varying conditions of the communication channel, TDMA and FDMA systems resort to separate users at different frequencies and / or time intervals and support frequency reuse to mitigate interference. Frequency reuse divides an available spectrum into many sets of frequencies. A given cell uses frequencies of only one set; the cells immediately adjacent to this cell may not use a frequency of the same set. In a CDMA system, the identical frequency is reused in each cell of the communication system, thereby improving the overall efficiency. The interference is mitigated by other techniques, for example, orthogonal coding, transmission power control, variable data rate and other techniques known to one skilled in the art. The concepts mentioned above were used in a development of a data traffic communication system known only as the High Speed Data Communication (HDR) system. This communication system is described in detail in the copending application serial number 08 / 963,386, entitled "METHOD AND DEVICE FOR THE TRANSMISSION OF HIGH SPEED PACKAGE DATA", filed on 3/11/1997, now US Patent No. 6,574,211 Issued on June 3, 2003, granted to the beneficiary hereof. The HDR communication system was standardized as an industry standard TIA / EIA / IS-856 hereinafter referred to as the IS-856 standard. The IS-856 standard defines a set of data rates, ranging from 38.4 kbps to 2.4 Mbps, at which an Access Point (AP) can send data to a subscriber station (Access Terminal (AT)). Because the access point is analogous to a base station, the terminology with respect to cells and sectors is the same with respect to voice systems. According to the IS-856 standard, the data to be transmitted on the FL are distributed in data packets, with each packet being transmitted over one or more intervals (time intervals), in which the FL is divided. At each time interval, the data transmission occurs from an access point to one and only one access terminal, located within the coverage area of the access point, at the maximum data rate that can be supported by the FL and the communication system. The access terminal is selected according to the conditions of the FL between the access point and the access terminal. FL conditions depend on the interference and path loss between an access point and an access terminal, both of which vary with time. The path loss and the path loss variation are exploited by programming the access point transmissions at time intervals, during which the FL conditions of the access terminal for a particular access point satisfy certain criteria that allow the transmissions with less power or higher data rate than the transmissions to the remaining access terminals, thus improving the spectral efficiency of the transmissions by the FL.

In contrast, according to the IS-856 standard, and the data transmissions on the RL occur from multiple access terminals located within a coverage area of an access point. In addition, because the antenna patterns of the access terminals are omnidirectional, any access terminal within the coverage area of the access point can receive those data transmissions. Consequently, transmissions over the RL are subject to several sources of interference: aerial channels multiplexed by code division of other access terminals, data transmissions of access terminals located in the coverage area of the access point (access terminals from the same cell) and data transmissions from access terminals located in the coverage area of other access points (access terminals of other cells). With the development of wireless data services, emphasis has been placed on increasing the performance of data on FL, following the model of Internet services; where a server provides high-speed data in response to a host's request. The server-to-host address is similar to that of an FL that requires higher performance, while host-to-server requests and / or data transfers are of lower performance. However, current developments indicate a growth of intensive RL data applications, for example, file transfer protocol (FTP), video conferences, games, constant bit rate services and the like. These applications require better RL efficiency to achieve higher data rates, so applications that demand high performance can be transmitted over the RL. Therefore, there is a need in the art to increase the data throughput on the RL, ideally to provide symmetric forward and RL outputs. Increasing the data throughput on the RL further creates the need in the art for a method and apparatus for power control and data rate determination. The foregoing and additional features of the invention are set forth with particularity in the appended claims and together with the advantages thereof will become clearer from the consideration of the following detailed description of the embodiments of the invention given by way of example with reference to the accompanying drawings. FIGURE 1 shows a conceptual diagram of a communication system. That communication system can be constructed in accordance with the IS-856 standard.

An Access Point (AP) 100 transmits data to an AT (AT) 104 on a forward link (FL) 106 (1), and receives data from the AT 104 on a Return Link (RL) 108 (1). Similarly, an AP 102 transmits data to the AT 104 on an FL 106 (2), and receives data from the AT 104 on an RL 108 (2). The transmission of data over the FL occurs from an AP to an AT at or near the maximum data rate that can be supported by the FL and the communication system. Additional FL channels, for example, control channel, can be transmitted from multiple APs to an AT. The communication of data about the RL can occur from an AT to one or more AP. The AP 100 and the AP 102 are connected to a controller 110 on the reverse paths 112 (1) and 112 (2). A "reverse path" is a communication link between a controller and an AP. Although only two ATs and one AP are shown in FIGURE 1, this is for explanation purposes only, and the communication system may comprise a plurality of AT and AP. After registration, which allows an AT to access an access network, the AT 104 and one of the APs, for example, the AP 100 establish a communication link using a predetermined access procedure. In the connected state, resulting from the predetermined access procedure, the AT 104 can receive data and control messages from the AP 100, and can transmit data and control messages to the AP 100. The AT 104 continuously searches for other APs that could be added to the active set of AT 104. An active set comprises a list of AP capable of communicating with AT 104. When an AP is found, AT 104 calculates the quality metric of the FL of the P, which may comprise a Signal Ratio to Interference and Noise (SINR). A SINR can be determined according to a pilot signal. The AT 104 searches for other ATs and determines the SINR of the APs. Simultaneously, the AT 104 calculates a quality metric of an FL for each AP in the active set of AT 104. If the FL quality metric of a particular AP is above a predetermined addition threshold or below a predetermined lowering threshold for a predetermined period of time, the AT 104 reports this information to the AP 100. Subsequent messages of the AP 100 may direct AT 104 to add or delete from the active set of AT 104 the particular AP. The AT 104 selects a service AP of the active set of AT 104 based on a set of parameters. A service AP is a? P selected for data communication to a particular AT or an AP that is communicating data to the particular AT. The parameter set may comprise any of one or more present or previous SINR measurements, a bit error percentage, a packet error percentage, for example, and any other known parameters. In this way, for example, the service AP can be selected according to the measurement of the largest SINR. The AT 104 then issues a data request message (DRC message) on a data request channel (DRC channel). The DRC message may contain a requested data rate, or alternatively, an indication of an FL quality, for example, the measured SINR, a bit error percentage, a packet error percentage and the like. The AT 104 can direct the issuance of the DRC message to a specific? P by the use of a code, which uniquely identifies the specific AP. Typically, the code comprises a Walsh code. The DRC message symbols are uniquely marked with OR '(XOR) with the unique Walsh code. This XOR operation is referred to as Walsh coverage of a signal. Since each AP in active set of AT 104 is identified by a unique Walsh code, only the selected AP that performs the identical XOR operation as performed by AT 104 with the correct Walsh code can correctly decode the DRC message.

The data to be transmitted to the AT 104 arrives at the controller 110. Therefore, the controller 110 can send the data to all APs in the active set of AT 104 on the reverse path 112. Alternatively, the controller 110 can determine first, which AP was selected by AT 104 as the service AP, and then send the data to the service AP. The data is stored in a waiting line in the AP. Then the paging message is sent by one or more AP to the AT 104 over respective control channels. The AT 104 demodulates and decodes the signals on one or more control channels to obtain the paging messages. At each FL interval, the AP can schedule data transmissions to any of the TAs that received the paging message. An example of a method for programming transmissions is described in U.S. Patent No. 6,229,795, entitled "System for allocating resources in a communication system", granted to the beneficiary hereof. The AP uses the speed control information received in the DRC message of each AT to efficiently transmit the data on the FL at the highest possible speed. Because the data rate can vary, the communication system operates in a variable speed mode. The AP determines the data rate at which to transmit the data to the AT 104 based on the most recent value of the DRC message received from the AT 104. Additionally, the AP uniquely identifies a transmission to the AT 104 using a code of propagation which is unique to that mobile station. This propagation code is a long pseudorandom (PN) noise code, for example a propagation code defined by the IS-856 standard. The AT 104, for which the data packet is intended, receives and decodes the data packet. Each data packet is associated with an identifier, for example, the sequence number, which is used by the AT 104 to detect lost or duplicate transmissions. In that case, the AT 104 communicates the sequence number of the lost data packets via the RL data channel. The controller 110, which receives the data messages from the AT 104 via the P that communicates with the AT 104, then indicates to the AP that data units were not received by the AT 104. The AP then programs a retransmission of those. data packages. When the communication link between the AT 104 and the AP 100, which operates in the variable speed mode, deteriorates below a permitted level of reliability, the AT 104 first attempts to determine whether another AP in the variable speed mode can Support an acceptable data rate. If the AT 104 finds that AP (for example, the AP 102), a reassignment of the AP 102 to a different communication link occurs. The term reassignment is a selection of a sector that is a member of an active list of TA, where the sector is different from the sector currently selected. Data transmissions continue from the AP 102 in the variable speed mode. The aforementioned deterioration of the communication link can be caused, for example, by the movement of the AT 104 from a coverage area of the AP 100 to the coverage area of the AP 102, overshadowing, fading and other well-known reasons. Alternatively, when a communication link between the AT 104 and another AP (e.g., AP 102) that can achieve a higher total rate than the communication link currently used becomes available, a reassignment of the AP 102 to a different communication link, and data transmissions continue from the AP 102 in the variable speed mode. If the AT 104 can not detect an AP that can operate in the variable speed mode and support an acceptable data rate, the AT 104 transits in a fixed speed mode. In that mode, the AT transmits at a speed.

The AT 104 evaluates the communication links with all the candidate APs for both data modes at variable speed and data at fixed speed, and select the AP, which produces the highest performance. The AT 104 will change from the fixed-speed mode to the variable-speed mode if the sector is no longer a member of the active set of AT 104. The fixed-speed mode described above and the associated methods for transiting to and the fixed-speed data mode are similar to those described in detail in U.S. Patent No. 6,205,129, entitled "METHOD AND APPARATUS FOR VARIABLE AND FIXED FL SPEED CONTROL IN A MOBILE RADIO COMMUNICATION SYSTEM", granted to the beneficiary hereof. Other fixed velocity modes and associated methods for the transition to and from the fixed mode may also be contemplated if they are within the scope of the present invention.

FL Structure Figure 2 illustrates a structure of FL 200. It will be appreciated that the time durations, segment lengths, ranges of values described below are given by way of example only, and that other lengths of time, lengths may be used. of segment and ranges of values without departing from the principles underlying the operation of the communication system. The term "segment" is a unit of a Walsh code propagation signal that has two possible values. The FL 200 is defined in terms of tables. A frame is a structure comprising 16 time slots 202, each time slot 202 being 2048 segments in length, corresponding to a duration of the time slot of 1.66 ms, and consequently, a frame duration of 26.66 ms. Each time slot 202 is divided into two half timesteps 202a, 202b, with pilot bursts 204a, 204b transmitted within each half-time interval 202a, 202b. Each pilot burst 204a, 204b is 96 segments in length, centered around a midpoint of its associated half-time interval 202a, 202b. The pilot bursts 204a, 204b comprise a pilot channel signal covered by a Walsh cover with zero index. An access medium access control channel (MAC) 206 forms two bursts, which are transmitted immediately before and immediately after the pilot burst 204 of each half time slot 202. The MAC is comprised of up to 64 code channels, which are covered orthogonally by Walsh 64-year codes. Each code channel is identified by a MAC index, which has a value between 1 and 64, and identifies a Walsh code of 64-year unique coverage. A Return Power Control (RPC) channel is used to regulate the power of the RL signals for each subscriber station. The RPC is assigned to one of the available MACs with a MAC index of between 5 and 63. The FL traffic channel or the payload of the control channel is sent in the remaining portions 208a of the first half-time slot 202a and the remaining portions 208b of the second half-time slot 202b. The traffic channel carries user data, while the control channel carries control messages and can also carry user data. The control channel is transmitted with a cycle defined as a period of 256 intervals at a data rate of 76.8 kbps or 38.4 kbps. The term user data, also referred to as traffic, is information different from that of air data. The term "aerial data" is information that allows the operation of entities in a communication system, for example, call maintenance signaling, diagnostic and reporting information, and the like. To support transmission through the RL, a Packet Transfer (PG) channel is needed in the FL. The aforementioned modulation of the RPC channel changes from the Binary Phase Inversion (BPSK) to a Quadrature Phase Inversion (QPSK), to support orders of the PG channel. The power control commands are modulated in the in-phase branch of the RPC channel assigned to an AT. The information of the power control order is binary, where a first value of one power control bit ("up") commands the TA to increase the transmission power of the AT and a second value of one control bit of the AT. power ("down") commands the TA to decrease the transmit power of the AT. As illustrated in Figure 3, the "up" order is represented as +1; the "down" order is represented as -1. However, other values may be used. The PG channel is communicated on a quadrature branch of the RPC channel assigned to the AT. The information transmitted on the PG channel is ternary. As illustrated in Figure 3, the first value is represented as +1, the second value is represented as 0, and the third value is represented as -1. The information has the following meaning for both the AP and the AT: +1 means that permission has been granted to transmit a new packet; 0 means that the permission to transmit a new package has not been granted; and -1 means that permission has been granted to transmit an old packet (retransmission). The signaling described above, in which the transmission of information of value 0 does not require signal power, allows the AP to assign power to the PG channel only when transmitting an indication to transmit a packet. Because only one or a small number of ATs were granted permission to transmit over the RL in a time interval, the PG channel requires very little power to provide transmission information by the RL. Consequently, the impact on the RPC power allocation method is minimized. The power assignment method of RPC is described in US Patent Application Serial No. 09 / 669,950, entitled "METHODS AND APPARATUS FOR POWER ALLOCATION TO BASE STATION CHANNELS", filed on September 25, 2000, now Patent. US No. 6,678,257 issued on January 13, 2004 granted to the beneficiary hereof. In addition, the AT is required to make a ternary decision on the quadrature flow only when the TA is waiting for a response after a request for data transmission, or when the TA has a pending data transmission. However, it will be appreciated that the choice of ternary values is a design choice, and values, other than those described in place, can be used. The AT receives and demodulates the RPC / PG channel of all the APs in the active set of AT. Consequently, the AT receives the information of the PG channel carried over the quadrature branch of the RPC / PG channel for each AP in the active set of AT. The AT can filter the information energy of the received PG channel over an update interval, and compare the filtered energy against a set of thresholds. By choosing the appropriate thresholds, the ATs that have not been granted permission to transmit, decode the cellular energy assigned to the PG channel as 0 with a high probability. The information transported on the PG channel is also used as means for the Automatic Retransmission (ARQ) request. As discussed below, a transmission by the RL of an AT can be received over several APs. Accordingly, the information transmitted in response to the transmission by the RL over the PG channel is interpreted differently when it is transmitted by a service or non-service AP. The service AP generates and transmits the permission to transmit a new packet as a response to the request of an AT that transmitted a new previous packet of the AT received correctly. Consequently, that information about the PG channel serves as an acknowledgment or acknowledgment (ACK). The service AP generates and transmits the permission to retransmit the previous packet in response to the request of the AT to transmit a new packet if the previous packet of the AT was received incorrectly. The AP that is not of service generates and transmits a value that indicates a permission to transmit or correctly receive a previous package of the AT. Consequently, that information about the PG channel serves as an ACK. The AP that is not of service generates and transmits the value indicated by a permission to retransmit or correctly receive the previous package of the TA. Consequently, that information about the PG channel serves as NACK. Therefore, a separate ACK / NACK channel is not necessary. It is possible for an AT to receive conflicting information about the PG channel, for example, because some? P did not receive the transmission correctly from the TA, because the information about the PG channel was erased or received incorrectly, or because other known reasons. Because, from the perspective of the access network, it does not matter, which AP received the transmission of the AT, when the AT receives information about the PG channel interpreted as an ACK of any AP, it transmits a new packet in the next transmission transfer, although the service AT may send a permission to retransmit an old packet. It will be appreciated that the present teaching is applicable to different FL structures. Thus, for example, the FL channels described above can be transmitted non-sequentially but simultaneously. Additionally, any FL can be used instead, which allows the communication of the information provided in the PG channel, for example, a separate PG and ACK / NACK code channels. RL As discussed above, the quality and effectiveness of a data transfer depends on the conditions of the channel between a source terminal and a destination terminal. Channel conditions depend on interference and path loss, both of which vary over time. Therefore, the performance of the RL can be improved by methods to mitigate the interference. On the RL, all the ATs in an access network can transmit simultaneously on the same frequency (a set of frequency reuse) or multiple ATs in the access network can transmit simultaneously on the same frequency (set of frequency reuse greater than 1) . It should be noted that the RL as described here can use any frequency reuse. Therefore, any transmission by the RL of the AT is subject to several sources of interference. The most dominant sources of interference are: transmission of multiplexed air channels by code division of other ATs of the same cell as of other cells; transmission of user data by AT in the same cell; and transmission of user data by AT of other cells. Studies on the performance of the RL in Code Division Multiple Access (CDMA) communication systems indicate that the elimination of interference from the same cell can achieve a significant improvement in the quality and effectiveness of data transfer. The interference of the same cell in the communication system according to the IS-856 standard can be mitigated by limiting the number of ATs that can transmit simultaneously on the RL. Because there are two modes of operation, that is, the one that limits the number of ATs that they transmit simultaneously and the one that allows all the ATs to transmit simultaneously, the access network needs to indicate to the ATs, which mode will be used. The indication is communicated to the ATs at periodic intervals, i.e. at a predetermined portion of an FL channel, eg, each cycle of the control channel. Alternatively, the indication is communicated to the TAs only after the change by a broadcast message in an FL channel, eg, a return power control channel. When operating in limiting mode, the packaged FL transfer channel described above may be used to provide permission to or deny transmission to TAs requesting permission to transmit. The interference of the same cell can also be mitigated by the time division multiplexing traffic channel and the RL air channels, and by programming, which of the ATs requesting transmission will be allowed to transmit in the RL time interval. , for example, a table, or a time interval. The programming can take into account a part of the access network, for example, a multi-sector cell and can be carried out for example, by means of an AP controller. That method of programming mitigates only the interference of the same cell. Consequently, as an alternative, programming can take into account the entire access network, and can be carried out, for example, by means of controller 110. It will be appreciated that the number of ATs that they were allowed to transmit in a time interval has influence on the interference on the RL, and consequently the Quality of Service (QoS) on the RL. Therefore, the number of ATs that they were allowed to transmit is a design criterion. Consequently that number can be adjusted by the programming method according to the changing conditions and / or QoS requirements. Additional improvements can be achieved by mitigating the interference of another cell. The interference of another cell during the transmission of user data is mitigated by the timely transmission, the control of the maximum power and transmission speed of the user data of each AT within a multi-sector cell. A "timely transmission" (and multi-user diversity) means programming AT transmissions at time intervals in which a given opportunity threshold was exceeded. A time interval may be considered appropriate if a metric, determined according to an instantaneous quality metric of the RL channel in the time interval, an average quality metric of that RL channel, and a function that allows differentiation between users (as a function of impatience described below), exceeds an opportunity threshold. The method allows the AT to transmit user data at a lower transmit power and / or complete the transmission of a packet using fewer time slots. The lower transmission power and / or the conclusion of the transmission of a packet in less time intervals results in a reduced interference of the transmitting ATs in sectors of the multisector cell and, therefore, in the interference of another cell total lower than AT in adjacent cells. Alternatively, a better average channel condition will allow the terminal to use the available power to transmit at a higher data rate, thus making the same interference with other cells that the AT could produce using the same available power transmit at a speed of lower data. In addition to mitigating interference on the RL channels, path loss and path loss variation can be exploited by multi-user diversity to increase performance. The "multi-user diversity" results from the diversity of the channel conditions between the TAs. The diversity in the channel conditions between user terminals allows programming of AT transmissions at time intervals, during which the conditions of the AT channel satisfy predetermined criteria that allow transmissions with less power or higher data rate, thereby improving the spectral efficiency of the transmissions on the RL. These criteria include the quality metric of an AT RL channel that is better in relation to the average quality metric of the AT RL channel. A design of a programmer can be used to control the QoS of the TAs. Thus, for example, by diverting the programmer to a subset of AT, the subset can be given transmission priority, although the opportunity reported by those terminals may be less than the opportunity reported by terminals that do not belong to the subset. It will be appreciated that a similar effect can be achieved by employing a function of impatience discussed below. The term subset is a set whose members comprise at least one member, but up to all the members, of another set. Even using a timely transmission method, the transmitted packet can be received erroneously and / or deleted in an AP. The term erase is a failure to determine the content of the message with a required reliability. This erroneous reception means the inability of an AT to accurately predict the quality metric of the RL channel of the TA due to the influence of interference from another cell. The influence of the interference of another cell is difficult to quantify because the AT transmissions of sectors belonging to different multisector cells are not synchronized, are short, and are not correlated. To mitigate the incorrect channel estimate . and providing average interference, often, Automatic Retransmission Request (ARQ) methods are used. The ARQ methods detect packets lost or received erroneously in a physical layer or a link layer and request the retransmission of those packets from the transmitting terminal. Stratification is a method for organizing communication protocols in well-defined encapsulated data units between processing entities, that is, layers, in other decoupled circumstances. The layers of protocols are implemented in the TAs and APs. According to the Open Systems Interconnection (OSI) model, the protocol layer Ll provides the transmission and reception of radio signals between the base station and the remote station, layer L2 provides the correct transmission and reception of signaling messages, and layer L3 provides the sending of control messages to the communication system. The layer L3 originates and terminates signaling messages according to the semantics and timing of the communication protocol between the TAs and the APs. In an IS-856 communication system, the signaling layer of the air interface Ll is referred to as the Physical Layer, the L2 is referred to as the Link Access Control Layer (LAC) or the Medium Access Control Layer. (MAC), and L3 is referred to as the Signaling Layer. Above the Signaling Layer are additional layers, which according to the OSI model are numbered as L4-L7 and are referred to as the Transport, Session, Presentation and Application Layers. An ARQ physical layer is disclosed in U.S. Patent Application Serial No. 09 / 549,017, entitled "Method and Apparatus for Rapid Retransmission of Signals in a Communication System", filed on April 14, 2000, granted to the beneficiary of the I presented. An example of a link layer ARQ method is the Radio Link Protocol (RLP). The RLP is a class of error control protocols known as ARQ protocols based on the absence of acknowledgments (NAK). One such RLP is described in TIA / EIA / IS-707-A.8, entitled "DATA SERVICE OPTIONS FOR EXTENDED SPECTRUM SYSTEMS: TYPE 2 RADIO LINK PROTOCOL", hereinafter referred to as RLP2. Transmissions of original and retransmitted packets may be timely.

Return Link Channels FIGURES 4A-4C illustrate an architecture for generating transmissions on an RL. As illustrated in FIGS. 4A-4B, the transmission on the RL comprises a Pilot Channel (PC) 410, a Data Request Channel.

(DRC) 406, a channel of Recognition or Acknowledgment of Receipt (ACK) 408, a Packet Request (PR) channel 412, an RL 404 Traffic channel, an Indication channel of Return Speed (RRI) 402. As described below, an example of the RL waveform generated by the channel structure described in Figures 4A-4C and the accompanying text, is defined in terms of tables, being a frame a structure comprising 16 time intervals. Therefore, for tutorial purposes a time interval was adopted as a mre of a time interval. However, it will be appreciated that the concept of a time slot can be extended to any other unit, i.e. multiple time slots as a frame, and the like.

Pilot Channel The portion of the Pilot Channel 410 is used for coherent demodulation and estimation of a channel quality of RL. The portion of the Pilot Channel 410 comprises demodulated symbols with a binary value of? 0 '. Unmodulated symbols are provided to a block 410 (1), which traces symbols with a binary value of 0 'over symbols with a value of +1, and symbols with a binary value of? L' over symbols with a value of -1. The traced symbols are covered with a Walsh code generated by a block 410 (2), in block 410 (4).

Data Request Channel The portion of the Data Request Channel 406 is used by the AT to indicate to the access network the selected service sector and the requested data rate on the One Way Traffic Channel. The data rate of the requested One-Way Traffic Channel comprises a DRC value of four bits. The DRC values are provided to a block 406 (2), which encodes the four bit DRC value to produce biortogonal code words. The code word DRC is provided to a block 406 (4), which repeats each of the code words twice. The repeated codeword is provided to a block 406 (6), which traces the symbols with a binary value? 0 'over symbols with a value of +1, and symbols with a binary value of' l 'over symbols with a value of -1. The plotted symbols are provided to a block 406 (8), which covers each symbol with a Walsh code W_8 generated by a block 406 (10), according to a DRC cover identified by the index i. Each resulting Walsh segment is then provided to block 406 (12), where the Walsh segments are covered by the Walsh code W816, generated by a block 406 (14).

Return Rate Indication Channel The RRI channel portion 402 provides an indication of a packet type of RL. The indication of the type of packet provides the AP with information that helps the AP to determine whether the flexible decisions of a currently received packet can be flexibly combined with the flexible packet decisions previously received. As discussed above, the flexible combination takes advantage of flexible decision values, obtained from previously received packets. An AP determines the bit values (hard decision) of a packet by comparing the energies in bit portions of a decoded packet (flexible decision values) against a threshold. If an energy corresponding to a bit is greater than the threshold, the bit is assigned a first value, for example,? L ', otherwise the bit is assigned a second value, for example,? 0'. The AP then determines whether the packet was correctly decoded, for example, by performing a CRC check, or by any other equivalent or appropriate method. If that test fails, the package is considered deleted. However, the AP saves the flexible decision values (if the number of attempts to retransmit the packet is less than the maximum allowed attempts), and when the AP acquires flexible decision values from the next packet, it can combine the flexible decision values of packages already received) before comparing them against the threshold. The combination methods are well known and, therefore, do not need to be described here. A suitable method is described in detail in U.S. Patent No. 6,101,168, entitled "Method and Apparatus for Efficient Retransmission in Time Using Symbols Accumulation", granted to the beneficiary hereof. However, in order to flexibly combine packages such as the AT, you must know that the packages contain information that can be combined. The RRI value may comprise, for example, 3 bits. The Most Significant Bit (MSB) of the RRI indicates whether the packet is an original transmission or a retransmission. The remaining two bits indicate one or four packet classes according to the determined according to the speed of the packet code, the number of bits comprising the packet, and a number of retransmission attempts. To allow the flexible combination, the code rate of the packet, the number of bits comprising the packet remains the same in transmission and retransmission attempts. The RRI value is provided to block 402 (2), which bio-geographically codes the 3 bits to provide a codeword. An example of biorthogonal coding is illustrated in Table 1. Table 1 The codeword is provided to a block 402 (4), which repeats each bit of the codeword. The repeated codeword is provided to a block 402 (6), which traces the symbols with a binary value? 0 'on the symbols with a value of +1 and the symbols with a binary value of? L' on the symbols with a value of -1. The plotted symbols are further provided to a block 402 (8), which covers each symbol with a Walsh code generated by the block 402 (10), and the resulting segments are provided for further processing. To support more than four packet classes, the RRI value may comprise, for example, 4 bits. The Most Significant Bit (MSB) of RRI indicates whether the packet is an original transmission or a retransmission. The remaining three bits indicate one of the classes in the packet. Again, the number of bits that make up the packet remains the same in the transmission and retransmission attempts. The RRI value is provided to a block 402 (2), which encodes the 4 bits in a simple 15-bit code word. An example of simple coding is illustrated in Table 2.

Table 2 Alternatively, the RRI symbols can be used to indicate a range of speeds. For example, when the RRI symbols comprise four bits, each of the eight combinations (e.g., 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111) may indicate a pair of data rates. Again, the Most Significant Bit (MSB) of RRI indicates that the packet is an original transmission. Once the RRI symbols are decoded, the decoder performs a blind determination of the data rate according to two hypotheses, a hypothesis according to the first data rate of the pair of data rates determined according to the symbols of RRI, and the second hypothesis according to the second data rate of the pair of data rates determined in accordance with the RRI symbols. Similarly, the eight combinations (e.g., 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111) indicate a pair of data rates of a retransmitted packet. Alternatively, two parallel decoders can be used, one decoder decoding the data according to a data rate, and the second decoder decoding the data according to the second data rate. The concept that indicates whether the indirect data rate can be extended to any number of data rates to be indicated by the combination of bits, the only limitation being the ability of the decoders to decode the number of data rates before the following data to be decoded are received. Accordingly, if the decoder can decode all data rates, the RRI symbol may comprise a bit, indicating whether the packet is a new transmission or a retransmission. The additional processing of the code words proceeds as described above.

Channel Ready for Packages Each AT that wishes to transmit user data indicates to the service sector of the user terminal that user data are available for transmission in a future time interval and / or that the transmission of the future time interval is timely . A time interval is considered appropriate if an instantaneous quality metric of the RL channel time interval exceeds the average quality metric of that RL channel modified by an opportunity level determined according to additional factors, depending on the design of the system of communication, exceeds a threshold. The quality metric of the RL is determined according to a pilot return channel, for example, according to an equation (1): Fllt TX Pilot (n) TX Pilot (n) (1) where Tx_Pilot (n) is an energy of a pilot signal during a nth time interval; and Filt_Tx_Pilot (n) is an energy of a pilot signal filtered over the past k intervals. The filter time constant, expressed in intervals, is determined to provide adequate averaging of the RL channel. Consequently, Equation (1) indicates how good or bad the instantaneous RL is with respect to the average RL. The TA performs: Tx_Pilot (n) and Filt_Tx_Pilot (n) measurements, and the calculation of the quality metrics according to Equation (1) in each time interval. The calculated quality metric is then used to estimate quality metrics for a certain number of time intervals in the future. The determined number of time intervals is two. A method for that quality estimation is described in detail in the application of United States Patent Serial No. 09 / 974,933, entitled "METHOD AND APPARATUS FOR PROGRAMMING THE CONTROL OF TRANSMISSIONS IN A COMMUNICATION SYSTEM", presented on October 10, 2001, now US Patent No. 6,807,426 issued on October 19, 2004, granted to the beneficiary hereof. The method described above for estimating the RL quality metric is given as an example only. Thus, other methods may be used, for example, a method using a SINR predictor described in detail in U.S. Patent Application Serial No. 09 / 394,980, entitled "SYSTEM AND METHOD FOR PREDICTING EXACTLY THE SIGNAL-A RELATION INTERFERENCE AND NOISE TO IMPROVE THE PERFORMANCE OF THE COMMUNICATIONS SYSTEM ", presented on September 13, 1999, now US Patent No. 6,426,971 issued on July 30, 2002, granted to the beneficiary hereof. The factors that determine the opportunity level, include, for example, a maximum acceptable transmission delay t (from the arrival of a packet in the AT to the transmission of the packet), a number of packets in the waiting queue in the AT I (length of the transmission queue), and average performance on the RL. The factors mentioned above define a function of "impatience" ". The impatience function is determined according to the desired influence of the input parameters. For example, immediately after the arrival of a first packet for transmission to the waiting queue of the AT, the impatience function has a low value but the value increases if the number of packets in the waiting queue of the TA exceeds a threshold. The impatience function reaches a maximum value when the maximum acceptable transmission delay is reached. The length parameter of the waiting queue and the performance parameter of the transmission also affect the impatience function. The use of the three parameters mentioned above as inputs to the impatience function is given for purposes of explanation only; any number or even different parameters may be used according to the design considerations of a communication system. Additionally, the impatience function may be different for different users, thus providing differentiation of users. In addition, other functions than the impatience function can be used to differentiate between users. In this way, for example, each user can be assigned an attribute according to the user's QoS. The attribute itself can serve in place of the function of impatience. Alternatively, the attribute can be used to modify the input parameters of the impatience function. The impatience function '' can be used to modify the quality metric according to equation (2) (2) The relationship between the calculated values of Equation (2) and a threshold Ts can be used to define opportunity levels. In Table 3 a set of suitable opportunity levels is given by way of example. It will be appreciated that a different number of opportunity levels and different definitions may be used instead.

Table 3 The appropriate opportunity level is encoded and transmitted over the PR channel. The PR channel is transmitted if an opportunity level different from 0, that is, "without data to transmit", is to be indicated. The four levels of opportunity described above can be represented as two bits of information. The PR channel could be received in an AP with high reliability because any error during the reception of the PR channel can result in a possible programming of an AT that has not requested the transmission of user data or report a level of low opportunity. Alternatively, that error can result in programming failures of an AT that reported a high opportunity level. Consequently, the two bits of information will be provided with sufficient reliability. As described above, the timely transmission time interval is involved because both the AP and the TA have knowledge of a predetermined number of time intervals in the future, for which the appropriate level has been estimated. Because the timing of the APs and ATs is synchronized, the AP is able to determine at what time interval is the appropriate transmission time interval for which the transmitting terminal reported the opportunity level. However, it will be appreciated that other arrangements may be employed, in which the timely transmission time interval is variable, and is explicitly communicated to the AP. The value of the PR channel 412 according to the concepts described above, is expressed as a value of 2 bits. The PR value is provided to a 412 (2) block. which encodes the 2 bits to provide a code word. The code word is provided to a block 412 (4), which repeats each of the code words. The repeated codeword is provided to a block 412 (6), which traces the symbols with a binary value? 0 'on symbols with a value of +1, and the symbols with a binary value? L' on the symbols with a value of -1. The plotted symbols are then provided to a block 412 (8), which covers each symbol with a Walsh code generated by block 412 (10).

ACK Channel The portion of the ACK 408 channel is used by the AT to inform the access network if a packet transmitted over the One Way Traffic Channel has been successfully received or not. The TA transmits a bit of the ACK channel in response to all the Ida Traffic Channel intervals that are associated with a preamble addressed to the AT. The ACK channel bit can be set to? 0 '(ACK) if a packet of the One Way Traffic Channel has been successfully received; otherwise, the bit of the ACK channel can be set to l '(NAK). A packet from the One Way Traffic Channel is considered successful if you check a CRC. The bit of the ACK channel is repeated in a block 408 (2), and provided to a block 408 (4). Block 408 (4) traces the symbols with a binary value 0 'on symbols with a value of +1, and symbols with a binary value? L' on symbols with a value of -1. The plotted symbols are then provided to a block 408 (6), which covers each symbol with a Walsh code generated by block 408 (8). When an AT is in an imperceptible transfer, the packet can be decoded only by the non-serving sector.

Traffic Channel Consistent with the RL requirement formulated above, the portion of the Traffic Channel 404 transmits packets at data rates, ranging from 153.6 kbps to 2.4 Mbps. The packets are coded in block 404 (2) at speeds of coding, depending on the data speed. Block 404 (2) comprises the turbo encoder with coding rates of 1/3 or 1/5. The sequence of binary symbols at the output of block 404 (2) is interleaved by a block 404 (4). Block 404 (4) may comprise a channel interleaver returning the bit. Depending on the data rate and coding rate of the encoder, the sequence of interleaved code symbols is repeated in block 404 (6) as many times as necessary to achieve a fixed modulation symbol rate, and provided to a block 404 (8). Block 404 (8) traces the symbols with a binary value 0 'on symbols with a value of +1, and symbols with a binary value? L' on symbols with a value of -1. The plotted symbols are then provided to block 404 (10), which covers each symbol with a Walsh code generated by block 404 (12).

Return Link Architecture Figure 4C best illustrates the architecture of an RL channel. The Traffic Channel portion 404, and the channel of the RRI portion 402 are multiplexed by time division in block 414, and provided to the gain adjustment block 416 (1). After the gain adjustment, the time division multiplexed signal is provided to a modulator 418. The portion of the Pilot Channel 410, the portion of the Data Request Channel (DRC) 406, the portion of the Recognition Channel or Acknowledgment of Receipt. (ACK) 408, the portion of the Packet Ready Channel (PR) 412, are provided to the respective gain adjustment blocks 416 (2) -416 (5). After the gain adjustment, the respective channels are provided to the modulator 418. The modulator 418 combines the incoming channel signals, and modulates the combined channel signals according to an appropriate modulation method, for example, a binary phase inversion ( BPSK), in a quadrature phase version (QPSK), quadrature amplitude modulation (QAM), phase inversion 8 (8-PSK), and other modulation methods known to those skilled in the art. The appropriate modulation method may change according to the data rate to be transmitted as the channel conditions and / or other design parameters of the communication system. The combination of the incoming channel signals will change accordingly. For example, when a selected modulation method is the QPSK, the incoming channel signals will be combined over In-phase and Quadrature signals, and those signals will be propagated by quadrature. The selected channel signals are combined over In-phase and Quadrature signals according to the design parameters of the communication system, for example the distribution of the channels, so that the data load between the In-phase and Quadrature signals is balanced The modulated signal is filtered in block 420, converted upwardly to a carrier frequency in block 422, and provided for transmission.

Waveform of the Return Link An RL 500 generated by the structure of the channel described in Figures 4A-4C and the accompanying text above is illustrated in Figure 5A. The RL 500 is defined in terms of tables. A frame is a structure comprising 16 time slots 502, each time slot 502 being 2048 segments in length, corresponding to a time slot duration of 1.66 ms, and consequently, a frame length of 26.66 ms. Each time slot 502 is divided into two half-time slots 502a, 502b, with air channel bursts 504a, 504b transmitted within each half-time slot 502a, 502b. Each air channel burst 504a, 504b is 256 segments in length and is' transmitted at the end of its associated half-time interval 502a, 502b. The air channel bursts 504a, 504b comprise channels multiplexed by code division. Those channels comprise a pilot channel signal covered by a first Walsh code, a DRC covered by a second Walsh code, and an ACK channel covered by a third Walsh code and a PR channel covered by a fourth Walsh code. . The payload of the RL traffic channel and the RRI channel are sent in the remaining portions 508a of the first half-time interval 502a and the remaining portions 508b of the second half-time interval 502b. The division of the time slot 502 between the air channel bursts 504a, 504b and the payload of the RL traffic channel and the RRI channel 508a, 508b is determined in accordance with an increase over the temperature during the bursts of the air channel 504a, 504b, data throughput, link budget and other appropriate criteria. Illustrated in Figure 5A, the time division multiplexed RRI channel and the payload of the traffic channel are transmitted at the same power level. The power distribution between the RRI channel and the traffic channel is controlled by the number of segments assigned to the RRI channel. The number of segments assigned to the RRI channel as a function of the transmitted data rate, will be explained later. It will be appreciated that other methods of combining the RL channels, and consequently, the waveforms of a resulting RL according to the design criteria of a communication system, are possible. Thus, the RL waveform described above separates one of the air channels, the RRI channel, which needs to be decoded with a high degree of reliability, from the remaining air channels, in this way, the remaining air channels they do not present interference with the RRI channel. To further improve the reliability of the RRI channel decoding, the number of segments assigned to the RRI channel remains constant. This in turn provides a different power to be transmitted in the RRI channel portion of the RRI channel / traffic time slots 508a, 508b to a different power level than the traffic channel portion. This consideration can be justified by the better performance of the decoding, resulting from the decoder taking advantage of the knowledge that the number of RRI channel portions is fixed, and the knowledge of the power to which the RRI channel was transmitted. . The RRI channel and the Traffic channel are transmitted concurrently, being separated by a different code, for example, being covered by different Walsh codes, as shown in Figure 5B. Accordingly, each half-time slot 502 comprises an air channel portion 504, and a RRI channel portion and traffic 508. The air channel portion 504 comprises the DRC 510, the ACK 512, the PC 514, and the PR 516 Air channels are distinguished by different codes, for example, because they are covered by different Walsh codes. The RRI 518 is covered by a Walsh code different from that of the payload of the Traffic channel 520. The power, allocated between the separated RRI channel and the Traffic channel, is determined according to the data rate that is transmitted. The air channels and the Traffic channel are transmitted using the time division mode, as shown in Figure 5C. Accordingly, each half-time slot 502 comprises an air channel portion 504, and a Traffic channel portion 508. The air channel portion 504 comprises the DRC 510, the ACK 512, the PC 514, the PR 516 and the RRI. 518. Air channels are distinguished by different codes, for example, they are covered by different Walsh codes. An advantage of the RL waveforms described above is their simplicity. It will be appreciated that the teaching described above is applicable to different waveforms. Thus, for example, the waveforms need not contain bursts of pilot signals, and the pilot signal can be transmitted on a separate channel, which can be continuous or bursts.

Transmission of Data by the Return Link As discussed at the beginning, transmission by the RL occurs from at least one AT in one interval.

For tutorial purposes only, the transmission of data by the RL as described below uses an interval equal to a time interval. The transmission by the RL is programmed by an entity in an access network in response to the AT request to transport user data. The AT is programmed according to the quality metric of the AT channel in the interval over the RL, the average RL quality metric of the AT, and the impatience function. An example of RL data transmission is shown and will be explained with reference to Figure 6. Figure 6 illustrates a negotiation of data transmission by the RL for an AT for purposes of understanding. The concepts can be for multiple AT. In addition, only one service AT is displayed. It should be understood from the previous description, as the ACK and NACK transmission of the non-service terminals affects the transmission of data by the RL. Due to the access procedure, the service sector selection, and other procedures and call set-up based on the probability functions of the communication systems according to the IS-856 standard as described above, are not repeated. The AT (not shown) having received data to be transmitted evaluates the quality metric and the impatience function of the RL of the TA, and generates an opportunity level (OL 1). The AT also generates the packet data type and estimates the data rate. As discussed, the packet data type designates the packet as original or retransmitted. As described in more detail below, the method of determining the speed determines a maximum supported speed according to the maximum transmission power of the AT, transmits the assigned power to a pilot channel and a quantity of data to be transmitted. The AT then communicates the type of packet data and the requested data rate on the RRI channel, and the opportunity level on the PR channel of the RL in the n interval. A service AP (not shown) of the access network receives the RL and decodes the information contained in the interval n. the service AP then provides the opportunity level as the packet data type, and the requested data rate of all the ATs requesting permission to transmit data to a programmer (not shown). The programmer programs packages for transmissions according to programming rules. As discussed, in programming networks they try to minimize the interference of mutual RL between AT, achieving at the same time the required QoS or reliability of the data distribution. The rules include: i. the precedence to transmit is given to the AT to report the highest opportunity level; ii. in the case that several ATs report an identical opportunity level, precedence is given to the AT with the lowest transmitted performance; and iii. in case several TAs satisfy the rules (i) and (ii) the AT is selected at random; and permission is given to transmit to one of the TAs with data available for transmission even if the reported opportunity level is low to maximize the use of the RL. After having made a programming decision, the service AP transmits the programming decision for each of the ATs requesting permission to transmit on the PG channel. The AT receives the PG channel, decodes the programming decision (SD 0), and abstains from the transmission of the packet. Because the TA has data to be transmitted, the TA again evaluates the quality metric and the impatience function of the TA of the TA, and at this moment it generates a new opportunity level (OL 2).

The AT also generates the packet data type and estimates the data rate, and provides the type of packet data and requested speed over the RRI channel and, the opportunity level on the PR channel of the RL in the interval n + 1. The service AP receives the RL and decodes the information contained in the interval n + 1. The service AP then provides the opportunity level, the type of packet data, and the requested data rate of all ATs requesting permission to transmit data to the scheduler. After having made a programming decision, the service AP transmits the programming decision to each of the ATs that requests permission to transmit on the PG channel. As shown in FIG. 7, the service AP transmits an SD + 1 programming decision that grants the AT permission to transmit a new packet. The AT receives the PG channel and decodes the SD + 1 programming decision. The TA evaluates the quality metric and the impatience function of the AT RL. As illustrated in Figure 7, the TA determined an opportunity level equal to 0, that is, without data available for transmission, consequently, the TA does not transmit the PR channel in the time interval n + 2. Likewise, the TA determined an opportunity level equal to 0 for the interval n + 3, consequently, the TA, transmits the user data in the payload portions of the RL traffic channel in the appropriate time interval n + 3 In the time interval n + 4, the TA has data to be transmitted. The TA evaluates the quality metric and impatience function of the RL of the TA, and generates an opportunity level (OL 2). The AT also generates the packet data type and estimates the data rate, and provides the type of packet data and the requested data rate over an RRI channel, and the opportunity level over the PR channel of the RL in the interval n + 4. The service AP receives the RL and decodes the information contained in the interval n + 4. The service AP then provides the opportunity level, the type of packet data, and the requested data rate of all ATs requesting permission to transmit data to the scheduler. After having made the programming decision, the service AP transmits the programming decision for each of the TAs that request permission to transmit on the PG channel. As shown in Figure 7, the payload sent over the RL in the interval n + 3 is correctly coded in the access network. As a result, the service AP transmits an SD + 1 programming decision that grants the AT permission to transmit a new packet. Only the service AP receives and decodes the RL of the transmitting AT, consequently, the service AP programmer makes the programming decision only on the information provided by the service AP. The other APs of the access network also receive and decode the RL of the transmitting TA and provide information on whether the payload was successfully decoded to the service AP. Consequently, if any of the APs in the access network successfully decoded the payload, the service AP indicates an ACK on the PG channel, thereby preventing unnecessary retransmission. All APs that received load information send the payload information to a centralized entity to effect the decoding of the flexible decision. The central decoder then notifies the service AP if the decoding of the payload was successful. The TA receives the PG channel and decodes the SD + 1 programming decision. The TA evaluates the impatience quality and function metric of the AT RL. As illustrated in Figure ß, the TA determined an opportunity level equal to 0, that is, without data available for transmission, consequently, the TA does not transmit the PR channel in the time interval n + 5. Likewise, the TA determined an opportunity level equal to 0 for the interval n + 6, consequently, the TA, transmits the user data in the payload portions of the RL traffic channel in the appropriate time interval n + 6 The case for the access network that does not correctly decode the payload sent over the RL in the n + 3 interval is illustrated in Figure 7. To request the retransmission of the payload sent over the RL in the interval n + 3, The service AP communicates on PG an SD-1 programming decision that grants the AT to retransmit the old packet. The AT receives the PG channel and decodes the SD -1 programming decision. The TA evaluates the quality metric and impatience function of the RL of the TA. As illustrated in Figure 7, the TA determined an opportunity level equal to 0, that is, without data available for transmission, consequently, the TA does not transmit the PR channel in the time interval n + 5. Likewise, the TA determined an opportunity level equal to 0 for the interval n + 6, consequently, the TA, transmits the user data in the payload portions of the RL traffic channel in the appropriate time interval n + 6 In the time interval n + 7, the TA has data to be transmitted. The TA evaluates the quality metric and impatience function of the RL of the TA and generates an opportunity level (OL 1). The AT also generates the packet data type and estimates the data rate, and provides the type of packet data and the requested data rate on an RRI channel, and the opportunity level on the PR channel of the RL in the interval n + 7. The service AP receives the RL and decodes the information contained in the interval n + 6. The service AP then provides the opportunity level, the type of packet data and the requested data rate of all TAs requesting permission to transmit data to the programmer. After having made the programming decision, the service AP transmits the programming decision for each of the ATs requesting a permit to transmit on the PG channel. As shown in Figure 7, the retransmitted payload sent over the RL in the interval n + 6 was decoded correctly in the access network. Consequently, in response to the opportunity level in the AT sent in time interval n + 7, the service AP transmits an SD +1 programming decision that grants the AT permission to transmit a new packet. It will be appreciated that the service AP can schedule an AT according to its last received transmission request. It will be appreciated that the packet access network may not receive packets even after several retransmission attempts. To avoid excessive retransmission attempts, the communication system may provide retransmission attempts after a certain number of retransmission attempts (persistent interval). The lost packet is then handled by a different method, for example, a Radio Link Protocol (RLP).

Return Link Power Control As discussed, only an AT in a sector is transmitting data traffic over the RL. Because in the CDMA communication system all terminals are transmitting at the same frequency, each transmitting AT acts as a source of interference for the TAs in adjacent sectors. To minimize that interference on the RL and maximize the capacity, the transmit power of the pilot channel for each AT is controlled by two power control loops. The transmission power of the remaining air channels is then determined as a fraction of the transmit power of the pilot channel. The transmission power of the traffic channel is determined as a ratio of traffic power to pilot for a given data rate, corrected by an increase over the thermal difference between the air transmission and traffic intervals. The increase over the thermal difference is a difference between the floor of the received noise and the total received power measured by the AT.

Power Control of the Pilot Channel The power control loops of the pilot channel are similar to those of the CDMA system described in detail in U.S. Patent No. 5,056,109, entitled "METHOD AND APPARATUS FOR CONTROLLING THE TRANSMISSION POWER IN A MOBILE TELEPHONE SYSTEM CELULAR CDMA ", granted to the beneficiary of the present and incorporated herein as a reference. Other methods of power control were also contemplated and are within the scope of the present invention. The first power control loop (external loop) adjusts a reference point, so that an operating level is maintained, for example,. an elimination rate of the DRC channel. The reference point is updated every two frames after selection diversity in the APs, that is, the reference point is increased only if the measured DRC elimination percentage exceeds a threshold in all APs in the active set of AT, and decreases if the measured DRC removal percentage is lower than the threshold in any of the AP. The second power control loop (internal loop) adjusts the transmit power of the AT, so that the RL quality metric is maintained at the reference point. The quality metric includes an Energy Ratio per segment to Noise plus interference (Ecp / Nt), and is measured in the AP that receives the RL. Consequently, the reference point is also measured in Ecp / Nt. The AP compares the measured Ecp / Nt with the power control reference point. If the measured Ecp / Nt is greater than the reference point, the AP transmits a power control message to the AT to decrease the transmit power of the AT. Alternatively, if the measured Ecp / Nt is below the reference point, the AP transmits a power control message to the AT to increase the transmit power of the AT. The power control message is implemented with one bit of the power control. A first value of the power control bit ("up") commands the TA to increase the transmit power of the AT and a lower value ("down") commands the TA to decrease the transmit power of the AT. The power control bits for all the ATs in communication with each AP are transmitted to the RPC of the FL.

Power Control of the Remaining Air Channel Once the transmit power of the pilot channel during a time interval is determined by the operation of the power control loops, the power transmitted from each of the remaining air channels is determined as a ratio of the transmission power of the specific air channel to the transmission power of the pilot channel. The relationships for each airway are determined according to simulations, laboratory experiments, field trials and other design methods.

Traffic Channel Power Control The required transmission power of the traffic channel is also determined according to the transmission power of the pilot channel. The power of the required traffic channel is calculated using the following formula: Pt = PPiioto. G (r) A (3) where: Pt is the transmission power of the traffic channel; Ppiloto is the transmission power of the pilot channel; G (r) is a ratio of the traffic-to-pilot transmission power for a given data rate r; and A is a difference of increase over thermal (ROT) between air and traffic transmission intervals. The measurement of the ROT in air transmission intervals (air ROT) and a traffic transmission interval (ROT traffic), necessary for the calculation of A in the AP is described in the Patent No. 6,192,249 entitled "Method and apparatus for estimating the load of the RL", granted to the beneficiary hereof. Once the noise in both air and traffic transmission intervals is measured, A is calculated using the following formula: A = ROI 'trafiCo -ROTarea (4) The calculated A is then transmitted to the TA. The A is transmitted on the RA channel. The value of A is then adjusted by the TA according to the percentage of packet error (PER) of the RL determined according to the ACK / NAK received from the AP, on the PG channel, so that a given PER is maintained in a maximum number of transmissions of a given package. The packet error rate of the RL is determined in accordance with the ACK / NACK of the RL packets. The value of A is first increased by a predetermined amount if an ACK has been received within N attempts to retransmit the maximum M retransmission attempts. Likewise, the value of A decreases by a second determined amount if an ACK has not been received within the N attempts to retransmit the M maximum retransmission attempts. Alternatively, A represents an estimate of the ROT difference given by Equation (3) at a subscriber or subscriber station. An initial value of A is determined according to simulations, laboratory experiments, field trials and other suitable design methods. The value of A is then adjusted according to the percentage of package error (PER) of the RL so that a given PER is maintained in a maximum allowed number of transmissions of a given packet. The packet error rate of the RL is determined in accordance with the ACK / NACK of the RL packets as described above. The value of A is increased by a first determined amount if an ACK has been received within the N retransmission attempts of the maximum M retransmission attempts. Similarly, the value of A decreases by a second determined amount if an ACK has not been received within the N retransmission attempts of the maximum M retransmission attempts.

From Equation (3), it follows that the transmission power of the traffic channel is a function of the data rate r. Additionally, an AT is restricted to the maximum amount of transmission power (Pmax). Therefore, the AT initially determines how much power is available from the Pmax and the determined Ppiloto. The AT then determines the amount of data to be transmitted, and selects the data rate r according to the available power and the amount of data. The TA then evaluates Equation (3) to determine if the effect of the estimated noise difference A does not result in exceeding the available power. If the available power is exceeded, the AT decreases the data rate r and repeats the process. The AP can control the maximum data rate at which an AT can transmit by providing the AT with a maximum allowable value G (r> -A through the RA channel.) The AT determines the maximum amount of transmit power of the channel. RL traffic, the transmit power of the RL pilot channel, and use Equation (3) to calculate the maximum bearable data rate.

RRI Channel Power Control As discussed above, the transmission power of the air channels is determined as a ratio of the specific air channel transmission power to the transmit power of the pilot channel. To avoid the need to transmit the RRI portion of the time slot of the channel traffic / RRI at a different power level than the portion of traffic, the portion of the traffic / RRI of the time interval is transmitted to it / power. To achieve the correct power distribution for the RRI channel, a different number of segments is assigned to the RRI channel as a function of the transmitted data rate. To ensure the correct decoding of a determined number of segments comprising a code word covered by Walsh, a required power can be determined. Alternatively, if the power for the traffic / payload necessary for a transmission is known, and the portion RRI of the traffic channel / time slot RRI is transmitted at the same power, the number of segments suitable to decode the RRI channel reliably can be determined. Consequently, once the data rate, and hence the transmission power of the time interval, of the Traffic / RRI channel is determined, so that it is the number of segments assigned to the RRI channel. The AT generates the bits of the RRI channel, encodes the bits to obtain symbols, and fills the number of segments assigned to the RRI channel with the symbols. If the number of segments assigned to the RRI channel is greater than the number of symbols, the symbols are repeated until all the segments assigned to the RRI channel are filled. Alternatively, the RRI channel is multiplexed by time division with the payload of the traffic channel and the RRI portion of the time slot of the traffic / RRI channel comprises a fixed number of segments. Furthermore, the power level of the RRI channel is not determined according to the transmit power of the pilot channel but a fixed value is assigned in accordance with the desired QoS, and communicated to each TA by means of an AP. The fixed value for a desired quality metric of the RRI channel reception is determined according to simulations, laboratory experiments, field tests and other design methods. The AT 800 is illustrated in Figure 8. The signals from the FL are received by the antenna 802 and routed to an input section 804 comprising a receiver. The receiver filters, amplifies, demodulates and digitizes the signal provided by the antenna 802. The digitized signal is provided to the demodulator (DEMOD) 806, which provides demodulated data to the decoder 808. The decoder 808, performs the inverse of the processing functions of signals made in an AT and provides decoded user data to the data collector 810. The decoder further communicates with a controller 812 by providing the controller 812 with aerial data. The controller 812 further communicates with other blocks comprising the AT 800 to provide appropriate control of the operation of the AT 800's, for example, data encoding, power control. The controller 812 may comprise, for example, a processor and a storage medium coupled to the processor and containing a set of instructions executable by the processor. The data of the user to be transmitted to the AT is provided by a data source 814 by orders of the controller 812 to an encoder 816. The encoder 816 is further provided with air data by the controller 812. The encoder 816 encodes the data and provides the data encoded to a modulator (MOD) 818. The data processing in the encoder 816 and the modulator 818 is carried out in accordance with the generation of the RL as described in the text and in the previous figures. The processed data is then provided to a transmitter within the input section 804. The transmitter modulates, filters, amplifies and transmits the RL signal over the air through the antenna 802, or the RL. The AT 800 also includes a mode selection / detection unit to determine the mode for transmissions. A controller 900 and an AT 902 are illustrated in Figure 9. The user data generated by a data source 904, are provided via an interface or interconnection unit, for example, a packet network interface, PSTN, (not shown) to controller 900. As discussed, controller 900 interfaces with a plurality of ATs, forming an access network . (Only one evaluation terminal 902 is shown in Figure 9 for simplicity). The user data is provided to a plurality of selector elements (only one selector element 912 is shown in Figure 9 for simplicity). A selector element is assigned to control the exchange of user data between the data source 904 and the data collector 906 and one or more base stations under the control of a 910 call control processor. The 910 call control processor it may comprise, for example, a processor and a storage medium coupled to the processor and containing a set of instructions executable by the processor. As illustrated in Figure 9, the selector element 902 provides the user data to a waiting queue 914, which contains the user data to be transmitted to the ATs (not shown) served by the AT 902. According to the control of a programmer 916, the user data is provided by the data queue 914 to a channel element 912. The channel element 912 processes the user data in accordance with the IS-856 standard, and provides the processed data to a transmitter 918. The data is transmitted over the FL through the antenna 922. The signals of the RL of the TA (not shown) are received in the antenna 924, and provided to a receiver 920. The receiver 920 filters , amplifies, demodulates and digitalizes the signal, and provides the digitized signal to the channel element 912. The channel element 912 performs the reverse of the signal processing functions performed in an AP, and provides decoded data to the selected element. r 908. The selector element 908 routes the user data to a data collector 906, and the aerial data to the call control processor 910. In some embodiments, a higher performance may be achieved in the transmissions by the RL by implementing an adaptive configuration in which the access network selects and allocates transmission modes for ATs in a sector, or on a subframe basis. In one embodiment, the mode assignment by the access network provides optional hybrid time slots, i.e. some of the modes that are assigned to the scheduler include hybrid CDM / TDM / OFDM transmission modes where OFDM refers to Multiplexing by Division of Orthogonal Frequency. In one embodiment of a communication system as illustrated in Figures, HA, 11B, 12A, 12B, 13A, and 13B below, a RL programmer in the access network selects and assigns a selected mode of transmission of the three transmission modes, referred to as mode 1, mode 2, and mode 3. In mode 1, the data is multiplexed by code division for the entire interval, that is, mode 1 is a 100% CDM mode. Mode 1 is the default mode, while mode 2 and mode 3 are optional hybrid modes. Because only TDM data is tolerant to delay, hybrid intervals will be used only for delay tolerant traffic. Typically, hybrid intervals are less likely to be used in applications such as Voice over Internet Protocol (VoIP), games and video telephony. Hybrid intervals are more likely to be used in applications such as FTP overload (file transfer protocol), and email type traffic. Regardless of the selected transmission mode, all the ATs transmit the aerial channels, through which the aerial data are transmitted, at the same time, using code division multiplexing. In mode 2, the data transmission is multiplexed by time division within each time interval between a first half-interval and a second half-interval. In the first half interval in mode 2, the data is multiplexed by code division, while in the second half-interval, the data is multiplexed by time division or multiplexed by orthogonal frequency division. Mode 2 is thus 50% CDM and 50% TDM / OFDM within a range. In mode 3, the data is multiplexed by time division within each time interval between a first fraction of the interval and a second fraction of the interval. The first fraction is a quarter (25%) of the time interval, and the second fraction is 3/4 (75%) of the time interval. In the first fraction (of a quarter or 25%) of the interval in mode 3, the data is multiplexed by division of code, while in the second fraction (of three quarters or 75%) of the interval in mode 3, the data are multiplexed by time division or multiplexed by orthogonal frequency division. It should be understood that although the modes described above are illustrated and discussed below, in other embodiments the hybrid modes may be characterized by time slot divisions in proportions other than 50% / 50% or 25% / 75%. Regardless of the transmission mode that is selected, the aerial data is transmitted using code division multiplexing. Regardless of the selected transmission mode, the same amount of air data is transmitted during a given time interval, and at the same power. Therefore, in higher modes, (for example in mode 2 which is 50% CDMA, or in mode 3 which is 25% CDMA), the gain of air channels increases, because it is transmitted the same amount of data (air) during a shorter CDMA time interval. In one embodiment of the communication system, each of the ATs is configured to compensate for the loss of energy during the transmission of the aerial data through the air channels, increasing the gain of one or more of the air channels. In one mode of the communication system, the TAs in flexible or more flexible transfer can use the modes with larger numbers. The loss in capacity caused by increased interference or another cell, which in turn is caused by higher transmit power levels of the ATs during the transfer, depends on the type of mode and the frequency of use. At least one inter-link in the RL operates in mode 1 at all times. The RL typically has three interences, that is, 4 continuous time intervals that are repeated every 12 intervals, one of which always operates in mode 1. The inter-link deviation RL i for the terminal is specified as: i- (T -Deviation of Frames) / 4 mod 3, (5) where T represents the time of the CDMA system, in units of time intervals, and 0 = i = 2. With hybrid intervals, the RAB (activity bit of return) is fixed, for load control, based on the intervals of mode 1 and even half of the (CDM) of the intervals of mode 2. For the intervals of mode 3, the load control is achieved by control of admission, that is, controlling the access of new communication requests to the network. In one mode of the communication system, the Access channel is transmitted only during the intervals of mode 1, and provided with a preamble of 2 intervals. There can be up to 64 payload intervals of the CDM channel. The start of the access probe is allowed in any sub-frame. For transmissions of the access probe, the AT uses the interlace of mode 1 and the portions of the CDM of mode 2 and mode 3. This results in larger delays for the access procedures. The delay depends on the frame deviation. In the best case scenario, the access delay is the same as the CDM (mode 1 only). In the worst-case scenario, the access delay may be significantly longer, depending on the size of the access payload and the data rate used. Figure 10 illustrates an example of the mode parameters, in a mode of the communication system in which the mode of transmission changed on a base per subframe. As explained at the beginning, the selection and assignment of the mode occurs on a sub-frame basis. In other words, a transmission mode, once assigned, can be changed only at the end of a subframe, or four time intervals, although the modes do not necessarily need to be changed at the end of each subframe. An assignment, once made, can be applied to several subframes. The assignment can often be applied at the discretion of the access network. For example, the mode assignment can be updated for each Control channel cycle, via a Synchronized Control Channel message. The selection mode is based on the Request channels. The RL programmer in the AN determines the mode to be used by a given subframe, depending on the applications of the data flows, and the resulting QoS requirements. The selection of the mode also depends on the total number of users in the sector, since the greater the number of users, the greater the bandwidth that is necessary for transmissions of the air channel. In one mode of the communication system, the RL programmer assigns the same mode to all TAs in the sector. To minimize intracell interference, the transmission in the TDM / OFDM fraction of the hybrid intervals gives the AT the following attributes: greater PA space, size of the active set, size of the active cell, and SINR value of the FL that is greater than a threshold, which can be approximately 5 dB, for example. The MAC parameters of the RL are not changed for the CDM transmission, while the TDM transmissions (during the hybrid intervals) all the MAC parameters of the RL are ignored. Figures HA and 11B illustrate a waveform of the RL on a subframe for mode 1, ie for a 100% CDM mode. In this mode, all ATs transmit the user data channel, as well as all air channels, concurrently (ie by multiplexing by code division). Each TA is distinguished from the others by the use of a long code mask and each channel for each TA is distinguished from the others by the use of a different Walsh code. The subpackage or CDM sub-frame, illustrated in Figures HA and 11B, is comprised of four time slots, each slot having 2048 segments. Figure HA illustrates a CDM sub-frame of mode 1 for a user for which higher modes (modes 2 or 3) that include TDM sub-frames are not programmed. Figure 11B illustrates a CDM sub-frame of mode 1 for a user for whom higher modes (ie hybrid modes 2 or 3) were programmed. As seen in Figures HA and 11B, the PR (packet ready) channel is optionally transmitted during CDM sub-frames, only if higher modes (hybrids) are programmed in TDM sub-frames. The air channel in the CDM sub-frame of mode 1 illustrated in Figure HA therefore does not include a PR channel, which is not transmitted during mode 1 CDM sub-frames if higher modes are not programmed. The air channel in the CDM sub-frame of mode 1 illustrated in Figure 11B does not include a PR channel, which is optionally transmitted if higher modes are programmed. In Figure HA, the ACK channel is shown with dotted strokes, indicating that the transmission of the ACK channel is optional in the CDM sub-frame of Mode 1 shown. Figures 12A, 12B and 12C illustrate a waveform of RL on a subframe for mode 2, ie, for a mode that is a TDM of 50% CDM and 50% TDM / OFDM. As seen from the schematic diagram illustrated in Figure 12A, in mode 2 the low speed channels (including the CDM and air data channels) and the high speed channels (TDM / OFDM data) are transmitted in disjoint time intervals. , that is, they are multiplexed by time division. The CDM fraction of a time interval, as well as the TDM / OFDM fraction of the time interval, each include 1024 segments. Figures 12B and 12C illustrate the TDM packets (with 50% of each packet being a CDM time slot, and 50% of each packet being a TDM / OFDM time slot) in greater detail. Figure 12B illustrates a TDM packet for an active TDM user, and Figure 12C illustrates a TDM packet for a free TDM user. As seen in Figures 12B and 12C, the PR channel is optionally transmitted during a CDM fraction of the time slots. The TDM packet for an active user, as illustrated in Figure 12B, shows the user data that is transmitted during the TDM / OFDM interval within the time interval, while the TDM packet for a free user, as illustrated in Figure 12C, does not show user data being transmitted during the TDM / OFDM interval within the time interval. The CDM data channel, the RRI channel, and the PR channel, all of which are shown in dashed boxes in Figures 12B and 12C, are optional transmissions in mode 2. During the air intervals in mode 2 , all users transmit their air channels, using multiplexing by code division. The air channels are transmitted to more than 1024 segments / interval, each channel covered with a different code. All delay sensitive packets are transmitted during the air interval, while the delay tolerant traffic is transmitted during the TDM / OFDM fraction. During the traffic intervals (ie the TDM / OFDM fractions of a time interval), each sector schedules the transmission by means of a single user. In terminals using only CDM time slots, all channels are interrupted for semi-even intervals (counting starts at zero), when operating in mode 2. A modified packet structure is provided, to ensure some coding gain with the Reduced package size. In terminals using only CDM time slots, a 2-slot RRI is provided in the air channels in the CDM time slot, for the transmission of CDM data. The gain and length (measures as the number of time intervals) of the DRC channel and the DSC channel are adjusted, to minimize the impact of performance during the mode 2 intervals. Also, the power of the RRI channel is increased by the traffic channels in the CDM interval, to compensate for shorter RRIs. The payload can be reduced, or the PILOT TRAFFIC can be increased, depending on the load of the sector. The reduction of the payload or the increase of TRAFFIC TO THE PILOT, is indicated by the FRAB (Filtered Return Activity Bit). For CDM traffic from mode 1 to mode 2, the power of the RRI channel is increased, along with TRAFFIC TO THE PILOT <; if FRAB (Filtered Return Activity Bit) is low. The power of the RRI channel decreases, along with the TRAFFIC to the PILOT, if the FRAB is high. The reason is that the RRI gain to the Pilot is higher if the FRAB is low. Similar rules apply for mode 2 to mode 3, and mode 1 for mode 3. For operation in legal mode (mode 1 only) the loss can be limited to restricting the number of intervals of mode 2 and mode 3. Examples of TDM packet parameters for mode 2 are given in Table 4. As seen in Table 4, the data rates of the RL range from 76.8 kbps to 1843.2 kbps. The range of the payload size is 512 bits to 12288 bits. The types of modulation used include the QPSK, 8-PSK, and 16-QAM. The number of RRI segments per interval decreases as a function of the gain of the Traffic channel.

Table 4 On terminals that use TDM transmissions (which for mode 2 occur at hybrid intervals only), the traffic channels have a data channel structure identical to the. which is used during CDM intervals. The Data channel and the Auxiliary pilot channel can be multiplexed by code division as an alternative, to provide greater flexibility in the allocation of power. The advantage is that this implementation is easier, in comparison with the data channels and RRI multiplexed by time division. The disadvantage is the highest PAR (peak to average power ratio). The terminals transmit - user data through the traffic channels in a way to achieve the maximum data rate achievable. The maximum achievable speed is based on the PA space (power amplifier), and the amount of • data in the buffer. The maximum achievable speed can be indicated by the AN via the Programming Transmission message, which provides a flexible power control mechanism. FIGS. 13A-13B illustrate an RL waveform over a subframe for mode 3, which is a TDM of 25% CDM and 75% TDM / OFDM. FIGURE 13A illustrates a TDM packet for an active TDM user, while FIGURE 13B illustrates a TDM packet for a free TDM user. As seen in both FIGURES 13A and 13B, in mode 3 CDM data is not transmitted during the CDM portion (25%) of the interval, and only the air channels (PR, ACK, DSC, DRC, and Pilot channels) are transmitted. . In other words, for ATs that use only CDM intervals, the transmission of user data does not occur. This is because only 25% of the interval was assigned to the CDM interval, so that there is not enough energy available in mode 3 for the transmission of CDM data during the CDM interval. Consequently, mode 3 should only be used if there is no need or desire to transmit CDM data. The RRI channel is also not transmitted in the CDM interval in mode 3, which is optionally transmitted during the CDM interval in mode 2. In mode 3, the optional transmission during the CDM interval is the PR channel transmissions and the ACK channel. The gain and length of the air channels in mode 3 can be adjusted to minimize the impact on performance relative to the mode 2 intervals. The loss of energy in the air channels can be compensated by increasing the gain of the air channel. Traffic channels, for terminals using TDM / OFDM transmission, are identical to those for mode 2 traffic channels, however, traffic channels in mode 3 can support higher data rates compared to mode 2 (because 75% of the interval was assigned to traffic data, compared to 50% in mode 2). A major advantage of mode 3 transmission is that a higher peak data rate can be supported, ie up to 3.1 Mbps. An example of TDM packet parameters for mode 3 is given in Table 5. As shown in FIG. In Table 5, the data rates of the RL range from 76.8 kbps to 3072.0 kbps, which represents a significant increase in the peak data rate. The range of the payload size from 512 bits to 20480 bits. The types of modulation used include QPSK, 8-PSK and 16-QAM. The number of RRI segments per interval decreases as a function of the gain in the Traffic channel, as in mode 2.

Table 5 In the embodiments described above of the communication system, in which optional hybrid ranges are provided, the AN is configured to receive from all the TAs in a sector a request to transmit data in a time slot. After receiving the request message from each TA, the AN assigns to each TA in the sector a transmission mode to transmit data, or on a base per subframe. As described above, the selection of mode can be based on the sector, that is, it can be assigned the same way to all TAs in a sector. The assigned mode or mode pattern can be announced a priori to all TAs in the sector. The AN (or an RL programmer within the AN) then programs a transmission, that is, decides which AT was allowed to transmit data during the requested data interval. The AN transmits to each AT a transmission message indicating the assigned transmission mode, as well as the assignment of the AT to which the transmission permission has been granted. In modes of the communication system in which hybrid intervals are optionally programmed, the power of the RL air channels and the RL traffic channels is controlled together by the mode 1 slots. For the mode 2 and mode modes 3, the power for air channels and traffic channels is controlled separately. Air channel power control is controlled using an internal loop and an external loop, as described at the beginning, and is based on a fixed gain between pilot and air channels. The internal loop is an OR of cells down. For the outer loop, the reference point is based on the White DRC Elimination Percentage in the BTS (cells) with the best PER (packet error percentage) of RL CDM Traffic, if available. The PC reference point (power control decreases), if the DRC removal percentage is approximately 25% AND the CDM data packet was decoded successfully. The PC benchmark is increased, if the DRC removal percentage is >; approximately 25% OR the Package (CDM data) was not decoded successfully. It should be understood, of course, that the 25% percentage interval was provided only as an example, and other percentage values may also be used for the percentage of DRC removal. The percentage of DRC elimination can be updated each table. Terminals using the CDM transmission mode can switch between mode 1, mode 2 and mode 3 ranges. By making appropriate adjustments to the TRAILER TOWARDS THE PILOT, the same PC reference point can be maintained through the transitions. . In one modality, the allocation of resources for MAC that flow in each TA in the sector are controlled also from the AN, in addition to the allocation of mode and user programming. An allocation of resources for a flow may contain, for example, the values TRAFFIC TO PILOT, TRAFFIC TO PILOTOmax, and TRAFFIC TO PILOT maintained for that flow in the TA, where TRAFFIC TO PILOT (ratio of traffic power to pilot) is the relationship between the transmission power of the traffic channel and the transmit power of the pilot channel, by the AT. This programmed resource allocation control is part of the IS-856-A, and provides a quick and efficient use of resources, as well as ease of design for QoS purposes. In particular, by providing TRAFFIC TO PILOT assignment control from the AN, that programmed resource allocation control allows a quick assignment or reassignment of all sector resources to each active flow. In this embodiment, the request message of the AT contains, in addition to a request to transmit data, in a time interval, an assignment request to assign a resource to the MAC flows within the TA. Each assignment request packet contains information about each RL MAC flow in the AT. FIGURE 14 illustrates a request packet format, in a mode that provides scheduled resource allocation control for MAC flows in the AT. The first byte of the Request packet contains a Request message header. The first four bits in the header of the Request message provide information about the maximum bearable TRAILER TO PILOT, that is, space. The next four bits of the Request message header provide the number N of MAC flows in the current Request packet. The request of each MAC flow (MAC flow 1, MAC 2 flow) then flows, one after the other consecutively. Each MAC flow request occupies 2 bytes, of which the first 4 bits provide a MAC flow ID for the MAC flow request, the next 4 bits provide the length of the wait row, the next 4 bits provide a critical wait row length, and the last 4 bits provide a critical dead line. The AT sends the Request packet, if and only if there is traffic channel data to be sent, and if the following conditions are satisfied: 1) a minimum number Nm_n of bits has been sent from the last Request packet, or 2) a predetermined time interval Tmax has elapsed since the last Request packet was sent, i.e. a predetermined time interval has elapsed without sending any Request packets. Condition 1) seeks to ensure that Petition packets are not sent very frequently, that is, that sufficient data has flown since the last Petition. Condition 2) seeks to ensure that Petition packages are not sent very sparingly, and that a Petition packet is sent at least once every Tmax. The AT leads to cost the Petition packets on the traffic channel data. The Petition can be reinforced in terms of energy for its rapid transmission. In one modality, Nm_n in condition a) above is given by: Nmin = (l / RelPet-l) * SizePackagePetition (6) where RelPet represents the desired ratio of request bits to traffic bits, and the size of PackagePatition Size varies with the number of flows in the request. The RelPet is chosen to ensure that the overload induced by the Request message is not very large, ie the volume of what was transmitted consists of traffic bits, not request bits. In addition to sending a Petition packet containing a request for allocation of resources, the request mechanism of the TA includes the transmission of the AT to the quality information AN of the RL channel. The TA generates the quality information of the RL channel by determining the opportunity levels, as described at the beginning. As described in detail in paragraphs 96-99 above, the opportunity levels are determined by requiring the relationship between the energy of a pilot signal filtered by the past k intervals, and the instantaneous energy of the pilot signal (ie energy). of the pilot signal during a nth time interval), is above a threshold value. In one modality, the opportunity levels are defined as listed in Table 3, above, with the following thresholds: for Opportunity Level 0 ("without data") Tx_Pilot (n), is more than about 3 dB above Filt_Tx_Pilot (n); for Opportunity Level 1 ("available data") Tx_Pilot (n) is within approximately 3 dB of Filt_Tx_ Pilot (n); for Opportunity Level 2 ("data available, channel condition" GOOD ") Tx__Pilot (n) more than approximately 3dB below Fil_Tx_Pilot (n); for Opportunity Level 3 (" data available, condition of channel ") VERY GOOD "") Tx_Pilot (n) is more than about 6 dB below Filt_Tx_Pilot (n) It should be understood that the threshold levels provided above (3dB and 6dB) are exemplary values that were provided for illustrative purposes, and other modes of the The communication system described above may have different threshold levels The number of opportunity levels, which in the example described above is three, may also be different in other embodiments of the communication system described in this patent. which are provided hybrid modes, the quality information of the RL channel can be transmitted through an R-CQICH channel (Quality Indicator Channel d the return Channel). In this mode, the RL channel quality information is transmitted from the TA to the AN only when hybrid intervals are to be programmed by the AN. The opportunity levels are transmitted over the R-CQICH channel using the QPSK modulation. The transmission or session mechanism for the AN, in response to the reception of the MAC Flow Request message and the opportunity levels transmitted on the R-CQICH (only when hybrid modes are programmed), includes: a) assigning a mode of transmission (as described above); 2) generate and send a Transmission message of resource allocation in response to the reception of the Request packet, and 3) generate and send the individual user transmission for the TDM / OFDM fraction of the hybrid intervals (for TDM traffic). When a Resource Allocation Transmission message is programmed for CDM traffic, the transmission message is transmitted over the FL Traffic channel, from the service sector to its ATs. The timing and content of the Transmission message is determined by the programmer of the AN. A Transmission message contains "transmissions" for one or more AT, and a transmission for an individual AT that contains the allocation of resources for one or more MAC flows within the AT. A resource allocation for a flow contains the values of TRAFFIC TO PILOT, TRAFFIC TO PILOTOmax, and TRAFFIC TO PILOT maintained for that flow. TRAFFIC A PILOT maintained is used to set an assignment from TRAFFIC TO PILOT until the last Transfer. The Transfer message contains new status variables and parameter values for specific flows. Upon receipt of the Transmission message, the AT overwrites its variables and RLMAC status parameters with the respective values received by each appropriate flow. The Transmission message can be sent via a multi-user package or the Control channel. When included in a multi-user package, a MAC_ID reserved in the MAC header in the multiuser packet is used to refer to the payload associated with the Transmission message. The transmissions or user sessions by TDM / OFDM fractions of hybrid intervals, generated in response to the reception of opportunity levels, are transmitted via FL PGCH (FL Packet Transmission Channel). The PGCH for TDM traffic is repeated for 2 intervals for greater reliability. FIGURE 15 shows the structure of a PGCH, which shows the coding, modulation and propagation for the PGCH. The error detection encoder 702 can be a CRC encoder. The convolutional encoder 704 has a restricted length (K) of 9. In the illustrated embodiment, a convolutional code rate of 1/4 is used. A total of 4 symbols of the convolutional encoder 704 are drilled, in block 706. The symbols of the drilling operation are interleaved by blocks, by the block interleaver 708. A total of 128 blocks interleaver symbols 708 are modulated using the QPSK modulator 710, then divided into a flow I and a flow Q, and propagated by a W8 code. A total of 512 segments of the propagation operation are plotted on the 512 MAC segments in the interval. In an alternative method, the PGCH is communicated over a quadrature branch of the RPC channel, using the signed / unsigned modulation of the tertiary mode, as explained above in conjunction with FIGURE 3. It will be appreciated that although the flowcharts were drawn In sequential order for its understanding, certain steps can be carried out in parallel in a real implementation. It will be appreciated that information and signals can be represented using any of a variety of different technologies and techniques. For example, the data, instructions, orders, information, signals, bits, symbols and segments that can be referred to by the above description can be represented by voltages, currents, electromagnetic waves, fields or magnetic particles, fields or optical particles or any combination of them. It will further be appreciated that the various illustrative logic blocks, modules, circuits and algorithm steps described in connection with the embodiments described herein may be implemented as electronic components, computer programming programs and systems, or combinations of both. To clearly illustrate this interchangeability of the physical computing or hardware components and programming and software or software systems, the various components, blocks, modules, circuits and illustrative steps have been described above, generally, in terms of their functionality. Whether that functionality is implemented as physical components of computing or hardware or software programs and systems depends on the particular application and design constraints imposed on the entire system. The experts can implement the described functionality in various ways for each particular application, but those implementation decisions should not be interpreted as departing from the scope of the present invention. The various illustrative logic blocks, modules and circuits described in connection with the embodiments described herein can be implemented or implemented with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a arrangement of Field Programmable Gates (FPGA) or other programmable logic device, discrete gate or logic of transistors, physical components described, or any combination thereof designed to perform the functions described herein. A processor for general purposes may be a microprocessor, but alternatively, a processor may be any processor, controller, microcontroller or conventional state machine. A processor may also be implemented as a combination of computing devices, for example a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The steps of a method or algorithm described in relation to the embodiments described herein can be incorporated directly into physical computing or hardware components, into a program module and programming systems or software executable by a processor, or into a combination of the two . A program or programming system or software module may reside in RAM, instant memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a "removable disk, a CD-ROM, or any other form of medium of storage known in the art.An example of storage medium is coupled to the processor, so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integrated into the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal. The above description of the described embodiments was provided to enable any person skilled in the art to make or use the present invention. Various modifications will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied without departing from the scope of the embodiments. Thus, the present invention is not intended to be limited to modalities shown herein, but according to the broadest scope consistent with the principles and novel features described herein. A portion of the description of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to facsimile reproduction by either the patent document or the patent description, as it appears in the patent file or registers of the Patent and Trademark Office, but otherwise reserves all copyrights. For the convenience of the reader, an alphabetical list of known acronyms is provided.

List of Acronyms AP Access Point ACK Recognition or Acknowledgment ARQ New Request for Automatic Retransmission ASIC Specific Integrated Circuit of the BPSK Application Binary Phase Inversion CDMA CRC Code Division Multiple Access CRC Cyclic Redundancy Check DRC Channel Data Request Message DSP Data Request Channel EcpINt Digital Signal Processor Energy Ratio by Segment to Noise More FDMA Interference Multiple Access by Frequency Division FPGA Array of Programmable Gateways in the FRAB Field Return Activity Bit FTP Filtering GOS File Transfer Protocol Service Degree HDR Data Rate High LAC Access Control MAC Link Access Control Channel of the MOD MOD Modulator MSB Most Significant Bit NACK Non-Service Access Point OFDM Orthogonal Frequency Division Multiplexing OL Opportunity Level OSI Open Systems Interconnection PC Pilot Channel PER PGCH Package Error Percentage PN Packet Transfer Pseudo Noise PR Ready for PSTN Packets Public Switched Telephone Network QoS Quality of the QPSK Service Investment in Quadrature Phase RA Return Activity RLP Protocol of the Radio Link ROT Increase on Thermal RPC Return Energy Control Channel RRI Indication of Return Speed SD Programming Decision SINR Signal Ratio A Interference and Noise TDMA Multiple Access by Division Time 3GPP 3rd Generation Society Project.

Claims (1)

NOVELTY OF THE INVENTION Having described the invention as above, property is claimed as contained in the following: CLAIMS

1. An Access terminal (AT), characterized in that it comprises: a processor; and a mode selection unit coupled to the processor, the mode selection unit adapted to select a multiple access transmission mode of a plurality of multiple access transmission modes.