Variable rate broadcast with soft handoff

[0001] The presented solution relates generally to wireless communication. More specifically, the embodiments of the invention described herein relate to providing variable data rate broadcasting with soft call forwarding in wireless communication.

Background _ [0002] Wireless communication systems are widely used to provide various types of transmission (such as voice and data) to many users. Such systems can be based on multiple access by code division (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), or other multiple access techniques. A wireless communication system can be designed to implement one or more standards such as IS-95, cdma2000, IS-856, W-CDMA, TD-SCDMA, and others.

[0003] The broadcast and multicast services provided in the wireless communication system have been designed to efficiently transmit large amounts of data from a single source point to a group of users.

Content suitable for such point-to-multipoint services includes news, stock quotes, sports events, movies, audio and video clips, and other multimedia data. As the demand for the transmission of multimedia data is increasing, there are challenges to improving spectral efficiency and maximizing the speed of data transmission in broadcast / multicast services.

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[0004] US 2003/00363 $ 4 describes a method and system for transmitting calls in a broadcast communication system.

Summary _ [0005] According to the invention, there is provided a device according to claim 1.

[0006] In accordance with the invention, a device is also provided

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Brief Description of the Drawings [0009] Fig. 1 shows a variant of the invention regarding a communication system;

[0010] Figs. 2A-2D illustrate a variant of the invention regarding the implementation of variable data rate broadcasting with soft call forwarding in the broadcast area of ​​a communication system;

[0011] Fig. 3 shows a variant of the broadcast system in the embodiment of Fig. 2D;

[0012] Fig. 4 is a flowchart of a process that can be used in an embodiment of the invention to implement variable data rate broadcasting with soft call forwarding;

[0013] Fig. 5 is a flowchart of a process that can be used in an embodiment of the invention to implement variable data rate broadcasting with soft call forwarding;

[0014] Fig. 6 is a flowchart of a process that can be used in an embodiment of the invention to perform broadcasting with

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Variable data rate with soft call forwarding;

[0015] Fig. 7 is a flowchart of a process that can be used in an embodiment of the invention to implement variable data rate broadcasting with soft call forwarding;

[0016] Fig. 8 is a block diagram of an apparatus in which some of the disclosed embodiments may be implemented; and [0017] Fig. 9 is a block diagram of an apparatus in which some of the disclosed embodiments may be implemented.

Detailed Description - [0018] Variants of the invention described herein relate to methods and systems for providing, in communication systems, broadcasting services with a variable data rate with soft call forwarding.

[0019] Unicast communication described herein may generally relate to any one-to-one voice transmission and / or data from a single source to a single receiver. In wireless (e.g., cell phone systems) communication systems, unit communication may include transmitting from one or more transmitters (e.g., in an access network) to a single receiver (e.g., an access terminal). The broadcast / multicast communication (or service) described herein may generally relate to any point-to-multipoint data transmission from a single source to a group of users in the broadcast area, which may include one or more sectors (or cells).

[0020] For the given broadcast services, the access network may receive the information stream from the information server and transmit information on the designated channel to a group of users in the broadcast area. Broadcast communication content (referred to herein as "broadcast content")

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EP 1 782 655 B1 may be hidden in data packets (referred to herein as "broadcast packets") as specified in the respective protocols (such as Internet Protocol (IP)). Broadcast content may include (but is not limited to) text, audio, images, video, data files, current software versions and other information.

[0021] The broadcast / multicast service may have controlled access, e.g., only users who are service subscribers receive the desired broadcast content on their access terminal devices.

subscribers do not have broadcast / multicast. can be achieved, for example, broadcast / broadcast content in only subscribers to decrypt the broadcast content. [0022] The access network controller (ANC) may relate to a portion of the communication system configured to connect to the backbone network (e.g. network of data packets) and route data packets between access terminals (AT) and backbone network, perform various functions of maintaining radio access and maintaining the link (such as soft call holding), control radio transmitters and receivers etc. ANC unit may contain and / or implement base station controller (BSC) functions, such as those used in second and third generation wireless networks. An ANC unit and one or more access points (APs) may form part of an access network (AN). The AP unit described here may also refer to a base station transceiver (BTS) system, an access network transceiver (ANT), a modem pool transceiver (MPT) or a B node (e.g., in a W-CDMA system), etc. The cell may refer to the coverage area served by the AP entity.

Users not having access to services

Such controlled access through encryption allows

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EP 1 782 655 B1

The cell may additionally contain one or more sectors. The broadcast area may contain one or more cells. [0023] The AT terminals described herein may relate to various types of devices, including them, cordless telephones, but not limited to cell phones, laptops, wireless communication cards for personal computers (PCs), personal digital assistants (PDAs), external or internal modems etc. The AT terminal can be any data device that communicates via a wireless or wired channel (e.g., via optical fiber or coaxial cable). The AT terminal may have different names, such as access unit, subscriber unit, mobile station, mobile device, mobile phone, mobile phone, remote station, remote terminal, remote unit, user device, user equipment, handheld device, etc. You can connect to the system attach different AT terminals. AT terminals can be portable or stationary and can be distributed in a communication system. The AT may communicate with one or more APs through the following connection and / or reverse connection at any given time. The following connection (or via the transmission of signals from the satellite to Earth) concerns the transmission from AP points to AT terminals. Reverse connection (or the transmission of signals from the Earth to the satellite) refers to the transmission from the AT terminal to the AP. [0024] In a wireless communication system performing broadcast / multicast services, soft handoff can be used to increase the broadcast transmission ratio. In soft call forwarding, identical transmissions from one or more APs can be received and combined at the AT, enabling AT terminals to maintain a higher data rate. Because broadcast content is to be received by many

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For users dispersed in the broadcast area, broadcast transmissions are typically identical in different cells in the broadcast area. In some systems, broadcasts may be in CDMA format, and each subscribing AT may programmatically combine transmissions from APs serving different cells, e.g., using a Rake receiver and / or an equalization receiver. In other systems, broadcasts may be in orthogonal ODFM frequency division multiplexing format, and each AT subscribing terminal may combine software transmissions from APs serving different cells, e.g. using a Fast Fourier Transform (FFT) modulation scheme .

[0025] In practice, cells in the broadcast area may have different acceptable data rates. Considering, for example, a broadcast area comprising a compact urban network with a skeleton of cells of limited capacity, which are usually small in size, surrounded by a suburban network with cells of limited coverage. Because the permissible data transmission rates usually change with a change in the total received power factor (e.g. from all cells involved in soft call forwarding) to the total interference power, the maximum allowed broadcast factor for a small urban cell may be higher than that for a large suburban cell. However, to perform soft call forwarding in such systems, it may be necessary to perform broadcast transmissions at the lowest permissible speed factor among many cells in the broadcast area, and thereby unduly limiting the spectral efficiency of the system.

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[0026] Therefore, there is a need to improve spectral efficiency and maximize the broadcast ratio of the broadcast / multicast service.

[0027] In order to improve the overall spectral efficiency, it is desirable to operate the broadcast transmission with a variable ratio with respect to cell coverings. In order to maximize the broadcast transmission ratio, it is desirable to operate the broadcast transmission in soft call forwarding. The embodiments described herein relate to methods and systems for providing broadcast / multicast services with a variable ratio, while maintaining soft call forwarding, thereby increasing the overall spectral efficiency and maximizing the broadcast ratio.

[0028] In a variant, a plurality of APs (e.g., serving different cells in the broadcast area) may transmit the broadcast content according to a set of speed coefficients. The rate coefficient set may contain many different data rates, each associated with a transmission format (e.g. specifying the number of transmission slots for transmitting the data packet), configured to allow APs to transmit broadcast packets to be incrementally combined (e.g., on a per-slot basis at susbribing AT terminals). For example, considering a set of coefficients covering three data rates: R1 = R (e.g. 1843.2kbps), R2 = R / 2 (e.g. 921.6kbps), and R3 = R / 3 (e.g. 614.4kbps), e.g. . associated with a transmission format with 1 slot, 2 slots and 3 slots respectively. The first slots of broadcast transmissions at the three coefficients are identical and can be combined software.

Second broadcast slots at

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EP 1 782 655 B1 coefficients to enable the above. The set of coefficients R2 and R3 are identical and can also be combined in software. Thus, to perform variable rate broadcasting, the rate set may be configured such as incremental combining as described in the rate factors may also be configured to support soft call forwarding in the broadcast area, as further described below.

[0029] Various aspects, features, and variants of the invention will now be described in more detail.

[0030]

FIG.

is a schematic diagram of a communication system 100 in which various variants of the invention may be implemented. For example, system 100 may include a plurality of AP 110 points, such as AP 110a-110c, each serving a cell (not shown in detail in Fig. 1). Various AT 120 terminals, including AT 120a-120d terminals, are located in different cells in the system. Each AT 120 terminal can communicate with one or more AP 110 points, i.e. depending on whether the AT terminal is active and in soft call forwarding.

[0031] In system 100, the ANC 130 may be connected to AP 110 and provide coordination and control for it. For example, the ANC 130 controller may be configured to control voice / data packet routing to the AT 120 terminals using the corresponding AP 110 points. The ANC 130 controller may additionally be connected to a data network i.e., via a packet data service (PDSN) node ( both of them are not shown in detail in Fig. 1). In some embodiments, the system 100 may be configured to support one or more wireless communication standards, e.g., IS-95, cdma2000, IS53 / 55P22996EN00

EP 1 782 655 B1

856, W-CDMA, TD-SCDMA, other wireless communication standards or a combination thereof.

[0032] System 100 may also be configured to perform broadcast / multicast services, e.g., in broadcast area 140. For example, ANC 130 may route broadcast content (e.g., received from a data network, which may also include an information server) to AP 110 points, which may in turn transmit broadcast content to AT 120 terminals in broadcast area 140.

[0033] In an embodiment, the broadcast / multicast service can be performed at a variable speed with soft call forwarding. For example, the ANC 130 may select a rate coefficient set containing a plurality of different data rates, each of which is assigned to a transmission format configured to allow incremental joining of broadcasts (as described above). The set of coefficients can be selected in relation to the permissible data transmission rates of cells served by AP 110 in the broadcast area 140, and the requirements for maintaining soft call forwarding in such cells, as further described below. The set of rate coefficients can also be selected in part based on the size of the broadcast content to be transmitted. The AN 130 node may then instruct AP 110 to transmit the broadcast content according to the selected set of coefficients. AT 120 terminals in broadcast area 140 may incrementally combine (e.g., per-slot) broadcast packets received from various AP 110 points. For example, AT 120b may incrementally combine broadcast packets originating from AP 110a, 110b, respectively,

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E.g., received via connections 150, 152, respectively. The AT 120c terminal may incrementally combine broadcast packets from AP 110b, 110c, e.g. received via connections 154, 156, respectively.

[0034] As described above, to implement various broadcast coefficients with soft call forwarding, the broadcast data rate and the corresponding transmission format configured in such for a cell, require a way to support soft call forwarding for the cell and adjacent cells that respond the cell for soft forwarding of the call, as the following example illustrates. To illustrate and clarify, coverage of soft call forwarding for a given cell (e.g., one or more adjacent cells that support a cell in soft call forwarding) includes adjacent cells in the examples below. This should not be considered as a limitation. The basic principles and procedures described here can be used in other situations where the soft call forwarding coverage extends beyond neighboring cells.

[0035] Figs. 2A-2D illustrate a variant of the invention of the broadcast area 200 in a communication system comprising a plurality of cells. For illustration and explanation, the cells shown in these figures have a uniform shape and size. This should not be considered as a limitation. In other embodiments of the invention, the cells may have different sizes and shapes (and may be non-targeted or composed of sectors). Also for clarity and simplicity, serving APs and AT terminals dispersed in such cells are not detailed in these figures.

[0036] Consider the A 210 cell (s) shown in Fig.

2A. Cell A 210 may, for example, be part of a dense network

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EP 1 782 655 B1 1 Let us assume that cell A 210 is capable of maintaining the data rate R, according to the transmission format of n slots (n is an integer, e.g. n = 1). In order to support soft call forwarding in cell A 210, adjacent cells (such as those shown with similar patterns) must also be able to support the 1-slot transmission format.

[0037] Fig. 2B illustrates a group of B 220 cells. Let us assume that each B 220 cell is also capable of maintaining the data rate R, i.e. also the 1-slot transmission format. In order to support soft call forwarding in each B 220 cell, adjacent cells (as those shown with similar patterns) must also be able to support the 1-slot transmission format.

[0038] Fig. 2C illustrates a group of C 230 cells that may, for example, be part of a large suburban network. Suppose that each C 230 cell is able to support the data transfer rate (n / m) R (n is an integer, e.g. n = 1, m = 3), corresponding to the 3-slot transmission format. In order to support soft call forwarding, each C 230 cell has adjacent cells (like those shown with similar patterns) also need to be able to maintain a 3-slot transmission format.

[0039] In order to meet the requirements to maintain soft call forwarding in all cells (e.g., A 210 cell, B 220 cells, and C 230 cells) as described above, each B 220 cell must be able to maintain a 1-slot transmission format and a 3-slot transmission format to assist cell A 210 and cell C 230 in soft call forwarding. Because the data rates are such that the first slots

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In broadcast transmission, both the 1 slot and 3 slot transmission formats are identical, each B 220 cell can be assigned to the 3 slot transmission format as shown in Fig. 2D (where B 220 cells are shown with similar patterns used for C 230 cells). In this way, the first broadcast slots in cell A 210 are identical and can be combined software. Because B cells 220 are able to maintain a 1-slot transmission format, ATs in B cells can successfully decode broadcast packets after the first slot; the other two broadcast slots can serve to support soft call forwarding in C 230 cells, as further illustrated in Figure 3 below.

[0040] Fig. 3 shows a variant of the broadcast scheme in the embodiment of Fig. 2D described above. Callout 310 is used to designate the pair of indicators used for the axis of each transmission slot. As shown in Fig. 3, for cell (s) A, transmission slots, outside the first slot, may be used for unicast transmission. Because B cells are capable of supporting the 1-slot transmission format, ATs in B cells can successfully decode broadcast packets after the first slot (as in cells A); the other two slots support incremental joining (e.g. on a per-slot basis) in C cells.

[0041] As shown in Fig. 2D and Fig. 3, B cells can act as "buffer" cells to effectively separate two coverage areas (e.g., cell (s) A and cell C) supporting different data rates simultaneously maintaining soft call forwarding. As discussed earlier, such buffer cells may be able to

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The maintenance of data rates of several neighboring cells (having higher allowable data rates) but assigned transmissions like that for the same format of other neighboring cells (having lower allowable data rates), thus allows neighboring cells to receive transmissions broadcast at various data rates while maintaining soft call forwarding (e.g. by enabling incremental merging as described above). This variable ratio approach improves overall spectral efficiency by minimizing the fraction of slots assigned to broadcasts, while maximizing the broadcast data rate by maintaining soft call forwarding. As shown in Fig. 3, without this approach, the broadcasts to A cells would have to be in a 3-slot transmission format, and as a result, the transmission slots assigned to the unit transmission would also have to be used for the broadcast transmission, thus limiting overall spectral efficiency.

[0042] Fig. 4 is a flowchart of a process 400 that can be used in an embodiment of the invention for performing variable data rate broadcasting with soft call forwarding. Step 410 assigns a nominal ratio to each cell relative to a cell in soft call forwarding with one or more (e.g., in a given soft cover

Nominal speed factor may take into account the maintenance of soft adjacent call forwarding cells), e.g. forwarding take calls that neighboring cells could provide. The nominal data rates assigned to different cells in the broadcast area are configured so

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EP 1 782 655 B1 allowed incremental joining as described above. Stage

420 identifies the minimum (or rate factor assigned to the cells with which calls the smallest neighbors) to each it is a nominal cell and and in soft cells considered in step 410 with the format speed (e.g. the same neighboring Step 430 assigns a broadcast data rate equal to each cell the minimum nominal coefficient thus identified.

[0043] Fig. 5 is a flowchart of a process 500 that can be used in an embodiment of the invention for performing variable data rate broadcasting with soft call forwarding. In step 510, a set of coefficients is selected, comprising a plurality of different data transmissions, each transmission being associated. Step 520 sends instructions to multiple APs to transmit broadcast content according to a set of speed factors, and the set of speed factors is configured to allow APs to transmit broadcast packets to be incrementally combined (e.g., on a per-slot basis at the AT terminal). In some embodiments, the data rates and the corresponding transmission formats in the set of rate factors can be selected and assigned to the APs of the permissible transmission rates supported by the APs, and the restrictions imposed by neighboring call forwarding cells, as for maintaining soft is described above. The set of rate coefficients can also be selected in part based on the amount of broadcast content to be transmitted.

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[0044] Fig. 6 is a flowchart of a process 600 that can be used in an embodiment of the invention to implement variable speed data broadcasting with soft call forwarding. In step 610, n slots for broadcasting content and (m - n) unicast slots are allocated to the first AP (min are integers and m&gt; n). In step 620, slots for transmitting broadcast content are allocated to the second AP. In step 630, m slots for transmitting broadcast content are allocated to the third point AP. In an embodiment, the first AP may act as the first cell capable of supporting R. data rate. The second AP may act as a second cell, adjacent to the first cell, which is also capable of supporting the data rate R. The third AP may act as the third neighbor cell, which is capable of supporting the data rate (n / m) R, as described above.

[0045] Fig. 7 is a flowchart of a process 700 that can be used in an embodiment of the invention to implement variable data rate broadcasting with soft call forwarding. In step 710, the slot index and is set to zero. At step 720, the transmission gap is selected and the slot index is increased by 1 (i = i + 1).

In step 730, it is determined whether i &lt;m, where m is the number of transmission slots assigned to the broadcast transmission. If the output of step 730 is "YES", in step 740 it goes on and identifies broadcast packets received from multiple APs in slot_i.

Then, in step 750, the received broadcast packets in slot_i are combined programmatically. (It should be noted that for

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In broadcasts in CDMA format, the received signals may first be broadcast again before being programmatically combined. For broadcasts in OFDM format, the received signals can be directly combined in software.) In process 700, you return to step 720 and continue the process in the next transmission slot. If "NO" is received at the output of step 730, the process 700 may, for example, continue with unicast processing as shown in Step

760.

[0046] Fig. 8 is a block diagram of an apparatus 800 that can be used to implement several of the embodiments of the invention shown (as described above). By way of example, the device 800 may include a rate set selection unit (or module) 810 configured to select the set of rates, comprising a plurality of different data rates, each associated with a transmission format, and a command sending unit 820 configured to send instructions to multiple APs for transmitting broadcast content according to a set of speed factors. The set of rate coefficients can be configured to allow incremental combining (as described above) of broadcast packets transmitted by APs.

[0047] In some embodiments of the invention, the rate factor selection unit 810 may, for example, carry out the process 400 The instruction sending unit 820 configured to carry out the process 600 shown in Fig. 6.

[0048] In the apparatus 800, the speed factor set selection unit 810 and the instruction sending unit 820 can be configured to that shown in Fig. 4 can, for example, be

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EP 1 782 655 B1 coupled to the communication bus

830.

Processing unit 840 and memory unit 850 may also be coupled to processing communication bus 830. Unit 40 may be configured to control and / or coordinate the activities of different units. Memory unit 850 may contain instructions to be executed by the 840 processor.

[0049] In certain embodiments of the invention, the device 800 may be implemented in an ANC (e.g., ANC 130 shown in Fig. 1), a main network controller, or other network infrastructure elements.

[0050] Fig. 9 is a block diagram of an apparatus 900 that can be used to implement some of the embodiments of the invention shown (as described above). For example, the device 900 may include a receiving unit (or module) 910 configured to receive data packets transmitted from multiple APs, an identification unit 920 configured to identify broadcast packets in received data packets, and a link-incremental unit 930 configured to connect incrementally identified broadcast packets. (e.g. on a per-slot basis). In some embodiments of the invention, the receiving unit 910, the identifying unit 920, and the combining-incremental unit 930 may, for example, be configured to carry out the process 700 shown in Fig. 7.

[0051] In the device 900, the receiving unit 910, the identification unit 920, the connecting-incremental unit 930 can be coupled to the communication bus 940. The processing unit 950 and the memory unit 960 can also be coupled to the communication bus

940.

Processing unit 950 may be configured to control and / or

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EP 1 782 655 B1 1 to coordinate the activities of various entities. The memory unit 960 may contain instructions to be executed by the processing unit 950.

[0052] In certain embodiments of the invention, the device 900 may be implemented in an AT terminal or other data receiving elements.

[0053] The variants presented herein (as described above) give several examples of broadcasting services with variable data rate with soft call forwarding. There are also other embodiments and implementations of the invention.

[0054] Various units / modules in Figs. 8-9 and other embodiments of the invention can be implemented in hardware, software, firmware or a combination thereof. In hardware implementation, various units can be implemented within one or more specialized electronic integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), user programmable gate matrices (FPGAs), processors, microprocessors, controllers, microcontrollers, programmable logic circuits (PLD), other electronic units and any combination thereof. In program implementation, you can implement various units with modules (e.g., procedures, functions and the like) that perform the functions described here. Program codes can be stored in a memory unit and executed by a processor (or processing unit). The memory unit may be implemented inside the processor or outside of the processor, in this case it may be communicatively coupled to the processor using a variety of elements known in the art.

[0055] The various illustrated embodiments of the invention may be implemented in a controller, an AT, and other components for providing a broadcast / multicast service. variants

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The invention described herein can be applied to a data processing system, wireless communication system, unidirectional broadcast system and in other systems in which efficient transmission of information is desired.

[0056] Those skilled in the art will recognize that information and signals may be presented using any of a variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips, which in the light of the previous description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles or any combination thereof.

[0057] One skilled in the art will recognize that various exemplary logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments of the invention described herein may be implemented in the form of electronic equipment, computer software, or combinations thereof. To better illustrate this interchangeability of hardware and software, various examples of components, blocks, modules, circuits, and stages have been described generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific applications and design constraints imposed on the entire system. Skilled artisans may implement the described functionalities by various methods for particular applications, but such implementation decision should not be interpreted as causing a departure from the scope of the present invention.

[0058] Various exemplary logic blocks, modules and circuits described in connection with the embodiments described herein can be implemented or made with a universal processor, digital signal processor (DSP), using specialized electronic integrated circuit (ASIC), user programmable logic gates (FPGA) or with other programmable logic devices, discrete gates

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EP 1 782 655 B1 or logic circuits based on transistors, discrete hardware components, or any combination thereof intended to perform the functions described herein. The universal processor can be a microprocessor, but as an alternative, the processor can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented as a combination of computers, e.g. a combination of DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core or other similar configuration.

[0059] The steps of the method or algorithm described in connection with the variants of the invention described herein can be embedded directly in the hardware, in the program module executed by the processor, or their combinations. The program module can be placed in direct access memory (RAM), flash memory, read only memory (ROM), electrically programmable ROM (EPROM), programmable electrically erasable permanent memory (EEPROM), registers, hard disks, removable disks, CD-ROM or other storage media known in the art. An exemplary storage medium is coupled to a processor that can read from it and write information to it. Alternatively, the storage medium may be integrated into the processor. The processor and storage medium can be placed in a specialized ASIC electronic integrated circuit. The ASIC can be located in the AT terminal. Alternatively, the processor and storage medium may be located as discrete components in the AT terminal.

[0060] The previous description of the presented embodiments serves to enable any person skilled in the art to apply or use the present invention. The various modifications in these variants will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other variants

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An embodiment of the invention without departing from the scope of the invention. Therefore, it is not an object to limit the present invention to only the embodiments shown here, but to the fullest extent protection in accordance with the claims.