The present invention relates, in general, to wireless communications systems, and, more particularly, to multiplexing data user transmissions with voice user transmissions over the same time-frequency resource.
While packet data traffic and applications have been rapidly increasing, the quality of voice transmission is still a fundamental aspect of designing wireless communication systems. Efficient management of coexisting voice and data users is important to network performance. For example, in a wideband code division multiple access (WCDMA) system, transmissions of packet data and voice over internet protocol (VoIP) traffic between a base station (BS) and user equipment (UE) are typically scheduled by the BS.
Voice traffic is typically discontinuous in nature and is generally composed of large inactive periods. It is often desirable to group a certain number of voice users together and assign them a set of shared time-frequency resources. A statistical multiplexing gain is, thereafter, achieved among the group members because not all of the users assigned to the group will need to use the shared resources at any one time (i.e., there does not have to be the same amount of resources assigned to each of the users in the groups; the group can efficiently operate with less than that total amount of resources allocated). When the BS has determined a discontinuous transmission (DTX) state for a particular user in a particular time period, it can assign that user's time-frequency resources to another user. The statistical multiplexing gain may also be achieved through early terminated hybrid automatic repeat request (HARQ) transmissions. Once a user acknowledges its VoIP packet, the time-frequency resources will usually become available to other group members based on the implemented scheduling algorithm.
A unique identifier, GroupID, is typically assigned when a group is established. As the BS assigns a UE to the group, it associates the UE's media access control (MAC) index (MACID) to the GroupID using a Group Setup Message managed by upper layer signaling. The BS will also typically assign resources to the group using a group grant message (group grant). Each group grant is generally identified by the GroupID and explicitly indicates the start of group resources. The bitmap identifying VoIP users in the group grant typically has one field with one or more bits for each VoIP user to indicate if that VoIP user is activated or not. Any activated voice user is generally able to locate its assigned resource blocks (RBs) by looking to the group grant.
A BS usually assigns a large number of RBs (e.g., 25 or the like) in a group grant for one or more groups to share. For each group, the start of the assigned group resources is generally designated so that it is the RB next to the end of previous group resource allocation. Any remaining RBs in the group grant may then be dynamically scheduled to data users with a data grant message.
Once a group of users is established, the group grant may also be used by the users to determine their exact resources within the set of shared time-frequency resources. The group grant is typically used for the first subpacket and subsequent retransmissions of that first subpacket. Each UE is generally assigned a unique ordering index within the group and a fixed interlace offset within a superframe for its first subpacket transmission. This ordering and interlace offset are used to align the time between successive first transmissions to the vocoder frame duration (approximately 20 msec).
When the VoIP user bitmap is configured to have a single bit, it generally indicates if the user is activated or not. This single bit method will typically be used with a default modulation coding scheme (MCS). When the VoIP user bitmap is configured to have more bits, it is often able to indicate not only the on/off activation state, but also the MCS options and number of RBs.
The UEs are also assigned an acknowledgement (ACK) position based on their position assignment in the first bitmap transmission. For example, with ‘N’ representing the total number of UEs in the specific sector, the first N/2 UEs in the first bitmap transmission will be assigned to transmit their ACK in the first ACK position, while the second N/2 UEs in the first bitmap transmission will be assigned to transmit their ACK in the second ACK position. Alternatively, an even/odd structure may be used, whereby UEs with an odd position assignment in the first bitmap transmission will be assigned to transmit their ACK in the first ACK position, while UEs with an even position assignment in the first bitmap transmission will be assigned to transmit their ACK in the second ACK position.
According to the statistical characteristics of voice traffic, the assigned size of the set of time-frequency resources and the acceptable VoIP latency and capacity are usually traded off carefully. In order to ensure a desired performance level, there are typically left-over resources in the group most of the time. With coexistence of both voice and data users, it is beneficial to include certain type of data users (for example, best effort traffic) in the group together with the VoIP users and have the data users take the left over resource for packet data transmissions. However, even dynamically assigning a particular set of resources to the data users, the unused RBs available to the voice users create a built-in inefficiency to this set-up.
Select ones of the various embodiments of the present invention multiplex the voice and data users, enabling them to share the same time-frequency resources to achieve an efficient utilization of the radio resource and, therefore, better performance of a wireless system. Other than dynamically scheduling data users with specific scheduling control messages, it saves the extra forward link control signaling overhead by having data users share the resource with voice users in multiple groups while maintaining higher priority for voice user transmissions.
Representative embodiments of the present invention provide methods for assigning communication resources to share between different types of users. The methods form user groups that include one or more first users of a first type and one or more second users of a second type. A plurality of resource blocks is assigned to the user group after which, a group setup message is transmitted to each user in the user group, where the message includes group parameters and identification of the resource blocks. A group grant message is also issued to each user in the user group. The group grant message provides group information allowing the resource blocks to be shared between the one or more first users of the first type.
Additional representative embodiments of the present invention provide methods for a data user to obtain communication resources in a wireless communication network. In these additional embodiments, the data user receives a group setup message at the data user identifying at least (1) a group of users sharing a set of communication resources, (2) the set of communication resources, and (3) a unique scrambling code for the data user. The data user further receives an active user signal identifying the data user as an active share data user, and receives a group grant message at the active share data user. The group grant message uses bitmap signaling for identifying a first boundary of a subset of the set of communication resources allocated to the active share data user and identifying a modulation and coding scheme (MCS) for the active share data user. The active share data user then uses the subset of the set of communication resources to perform data communication.
Additional representative embodiments of the present invention provide computer program products having a computer readable medium with computer program logic recorded thereon. The computer program products include code for forming a user group that includes one or more first users of a first type and one or more second users of a second type, code for assigning a plurality of resource blocks to the user group, code for transmitting a group setup message to each user in the user group, and code for issuing a group grant message to each user in the user group. The group setup message includes group parameters and identification of the plurality of resource blocks, while the group grant message provides group information allowing the plurality of resource blocks to be shared between the one or more first users of the first type.
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The present invention provides a novel method to have the voice and data users share the same time-frequency resource, which results in a more efficient utilization of wireless radio resource and thus improves the performance of a wireless system. It is understood, however, that the following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components, signals, messages, protocols, and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to limit the invention from that described in the claims. Well known elements are presented without detailed description in order not to obscure the present invention in unnecessary detail. For the most part, details unnecessary to obtain a complete understanding of the present invention have been omitted inasmuch as such details are within the skills of persons of ordinary skill in the relevant art. Details regarding control circuitry described herein are omitted, as such control circuits are within the skills of persons of ordinary skill in the relevant art.
In this example, N=25 VoIP users that are assigned to the group. TF indicators 102 for UE1 through UE‘N’ indicate the VoIP users being served with a single bit for each UE, or indicate the size of assigned resource and/or packet format with multiple bits for each UE
In operation according to group resource allocation 11, statistically, not all of RB0-RB7 will be used by active UE within G1103. Therefore, unused resources will statistically exist somewhere in RB0-RB7. Similarly, there will be unused RBs in the allocation of RB8-RB15 to G2104. Therefore, if the number of data users request resources exceeding the reserved dynamic allocation portion, RB16-RB24, such data users will be delayed access to transmission resources until such resources within RB16-RB24 become available. When unused resources exist within the allocations to G1103 and G2104 at the same time that data users are being delayed network access, the entire system is running inefficiently. However, the desire to maintain voice quality in current systems drives this inefficiency of the network.
In the next allocation time interval, TTI 107, the BS transmits group resource allocation 12. Within the intervening time, the number of voice users requesting network access decreased. Thus, the corresponding allocations to G1103 and G2104 have decreased to RB0-RB3 and RB4-RB11, respectively. As such, the amount of RBs reserved for dynamic data user allocation, D 105, is correspondingly expanded. Data users which were delayed or denied access to the network during implementation of group resource allocation 11 are now allowed to access the network through reserved RB12-RB24.
During the time of TTI 108, the number of voice users requesting network access has increased greatly. As such, the BS transmits group resource allocation 13 to the sector UEs. The entire 25 RB allocation is now divided exclusively between G1103 and G2104. RB0-RB11 to G1103 and RB12-RB24 to G2104. During this time period, while unused resources will exist within the two allocation sets, RB0-RB11 and RB12-RB24, data users will, nonetheless, have no available resources. This current methodology for allocating resources within such networks continues to perpetuate inefficient use of the network resources.
According to one aspect of the present invention, the Group Setup Message is sent by the base station to set up the grouping initially and to add users to the group. A group is defined with a set of group and user specified parameters, such as GroupID, resource location, number of VoIP users, number of data users, bitmap length, and the like. The Group Setup Message in Table 1 is sent to each VoIP user and the Group Setup Message in Table 2 is sent to each data user. As an example to minimize the overhead requirement on MCS indication, four MCS indices (Mod Coding—1, 2, 3, and 4) are set in Group Setup Message for a data user based on this user's channel condition. Consequently, only 2-bits are required to explicitly indicate the MCS index for that data user. The mapping from these bits to actual MCS can be adjusted by upper layer signaling, based on long-term channel quality and/or power availability.
For example, the first group usually starts from RB0 by default. Each mini MAC ID 215 can support one or multiple data users. When multiple data users share a single one of mini MAC ID 215, the scheduler has a constraint that it cannot consecutively schedule two users with the same mini MAC ID 215. MCS field 216 generally provides a number of bits to support multiple levels of MCS for the share data user. However, this field does not necessarily have to represent the absolute MCS levels. Instead, MCS field 216 may be various combinations of MCS and/or numbers of resource block allocation. Furthermore, any of the fields of bitmaps 210 for UE1-UE‘N’ can be used to indicate data users as well, as long as a fixed MCS level is pre-assigned for the data users.
Each one of mini MAC ID 236 can support one or more data users. NDI 235 indicates the arrival of a new packet. Multiple data users can, therefore, share a single one of mini MAC ID 236, because NDI 235 will let the receiver know if the incoming packet is new or a retransmission. As with the previous embodiment, MCS field 237 supports multiple MCS levels for the share data user.
As noted, the group grant for G1300 indicates that share data users are present in G1300. The group grant for G1300, therefore, identifies leftover G1 resource 310 that the share data users can occupy after reading the group grant for G2305. A scheduler at the base station decides (1) which data user is being served, (2) how much resource is assigned, and (3) which MCS is being used based on the channel quality, the quality of service (QoS) requirement, the buffer status, or the like. Each data user will look at the group grant for G1300 first to see if it is being activated to share and, if so, will look at the corresponding MCS. The activated share data user will then proceed to look at the group grant for G2305 which indicates the starting address of the resources assigned to G2305. The activated share data user will then calculate the occupied blocks and locate the exact blocks it has been effectively assigned to. If no resources are left from VoIP users according to the bitmaps, the MCS index value is ignored.
The encoded packet size of the share data packet depends on the size of assigned resource and the MCS scheme used. Padding may be added if the number of information bits is less than the encoded packet size. The scheduler at the base station balances the power and MCS of the data user.
It should be noted that the mapping from the MCS bits to actual packet format may be adjusted by upper layer signaling.
It should further be noted that, in additional and/or alternative embodiments of implementations of the present invention, if there is only one group (e.g., G1300, without G2305), the share data users only needs access to the group grant for G1 and the maximum shared resource to determine its assigned blocks.
It should be noted that a fixed number of resource blocks can be implicitly reserved with the group grants every time for dynamically granted data users, which will guaranteed the resource for the corresponding HARQ retransmissions. This mode is preferable because of these advantages. However, if there is only one group in an allocation scheme, e.g., G1 in resource allocation Mode 2, the maximum shared resource should be explicitly sent using an upper layer message so that the share data users can locate its assigned blocks.
In one example of operation within resource allocation Mode 3, there are two share data users; one provided for in each of the group grant messages. In order to locate their respective resource allocation, each share data user looks at both group grants to determine the location of leftover combined resource 345. Once determined, each share data user will share leftover combined resource 345 in a predefined fashion, e.g., each taking half of the available resource, each taking a certain percentage based on the compared signal strength, each taking a certain percentage based on a compared priority, and the like.
It should be noted that, in the configuration of resource allocation Mode 3, no starting point field is needed for either group grant. Thus, the group grants for G1340 and G2350 may use 10 bits for the mini MAC ID and MCS fields instead of the typical 5 bits. In this configuration, there may be one share data user occupying 10 bits for mini MAC ID and MCS, e.g., 5 bits for mini MAC ID and 5 bits for MCS. Compared with extended group grant 22 (
The group grant for G1360 has the original 5-bit grant header indicating the start of group resource. However, since the grant header for G2365 becomes larger, the VoIP bitmaps of G2365 are correspondingly reduced due to the fixed group grant size. Similarly to the previous resource allocation schemes, the size of the shared resources for the group users (i.e., voice/VoIP users of G1360, voice/VoIP users of G2365, and leftover G2 resource 370) are notified via upper layer signaling. The reserved resource 375, if any, is fixed so that the grant data users can be scheduled and have guaranteed HARQ retransmission resource. The share data users only need look at the last group grant to locate the leftover G2 resource 370 for their transmissions.
It should be noted that the example implementation described with respect to
It should further be noted that in any of the preceding embodiments, resource allocation Modes 1-5 (
In resource allocation Modes 1 through 5 (
For the retransmission of the data packets, there are various methods that may be used. One method is to simply delay the subpacket retransmission until the resource becomes available. Another method is to use adaptive retransmission, i.e., partitioning the subpacket to fit in the size of the left over resource for retransmissions. A more aggressive method is to allow the base station to reserve the resource in the group for any subpacket retransmission until this subpacket is acknowledged or the maximum number of retransmissions is reached. While this more aggressive method provides more definite resource availability, it may slightly affect the VoIP user transmissions. Another method for retransmitting data packets is simply to use any available resource within the reserved resource (e.g., reserved resource 315 (
To further alleviate the constraint over retransmission resources, power control may be used to target an earlier termination than set in the default so that the number of retransmissions can be reduced.
It should be noted that while the various alternative embodiments of the present invention described herein have been described in terms of VoIP and data users, additional and/or alternative embodiments of the present invention may be further generalized to two prioritized user types. For example, the first user type is classified as higher priority with, for instance, latency sensitive services, loss sensitive services, or the like, while the second type of users are of lower priority with, for instance, latency insensitive services, loss insensitive services, or the like. Regardless of whether the two user types are voice/VoIP and data or simply higher priority vs. lower priority, the methods and configurations described above still equally apply.
It should further be noted and obvious to those skilled in the art that other ways of setting the values of bits in group grants are possible without deviating from the spirits of the present invention.
In managing sector 400, BS 401 divides mobile units 404 and 407-414 into groups through a Group Setup Message. The Group Setup Message includes assignment of a GroupID, and MAC ID, and associates the unique identifier for each of mobile units 404 and 407-414 to its specific GroupID. In the operation illustrated in
Although the messages are sent by the base station and received by the mobile station in various examples illustrated in the previous sections, the present invention contemplates to use these novel methods on the messages sent by any one communications terminal and received by any other communications terminal.
The various illustrative logical blocks, modules, and circuits described in connection with the embodiment disclosed herein may be implemented or performed with, but not limited to, a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a memory device such as RAM, ROM, EPROM, or EEPROM, a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, and any combination thereof designed to perform the functions described herein.
The program or code segments making up the various embodiments of the present invention may be stored in a computer readable medium or transmitted by a computer data signal embodied in a carrier wave, or a signal modulated by a carrier, over a transmission medium. The “computer readable medium” may include any medium that can store or transfer information. Examples of the computer readable medium include an electronic circuit, a semiconductor memory device, a ROM, a flash memory, an erasable ROM (EROM), a floppy diskette, a compact disk CD-ROM, an optical disk, a hard disk, a fiber optic medium, a radio frequency (RF) link, and the like. The computer data signal may include any signal that can propagate over a transmission medium such as electronic network channels, optical fibers, air, electromagnetic, RF links, and the like. The code segments may be downloaded via computer networks such as the Internet, Intranet, and the like.
Bus 602 is also coupled to input/output (I/O) controller card 605, communications adapter card 611, user interface card 608, and display card 609. The I/O adapter card 605 connects storage devices 606, such as one or more of a hard drive, a CD drive, a floppy disk drive, a tape drive, to computer system 600. The I/O adapter 605 is also connected to a printer (not shown), which would allow the system to print paper copies of information such as documents, photographs, articles, and the like. Note that the printer may be a printer (e.g., dot matrix, laser, and the like), a fax machine, scanner, or a copier machine.
Obviously, numerous variations and modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the form of the present invention described above and shown in the figures of the accompanying drawing is illustrative only and is not intended to limit the scope of the present invention.
This application claims the benefit of U.S. Provisional Application No. 60/895,072, filed on Mar. 3, 2007, entitled “SIGNALING SUPPORT FOR GROUPING DATA AND VOICE USERS TO SHARE THE RADIO RESOURCES IN WIRELESS SYSTEMS,” which application is hereby incorporated herein by reference. This application is related to: U.S. Application Ser. No. 60/824,284, filed on Aug. 31, 2006, entitled “METHOD AND APPARATUS FOR GROUPING USERS TO SHARE THE SAME TIME-FREQUENCY RESOURCES IN A WIRELESS COMMUNICATIONS SYSTEM”, by Jianmin Lu, Tao Wu, Yunsong Yang, and Quanzhong Gao; and U.S. Application Ser. No. 60/791,700, filed on Apr. 13, 2006, entitled “METHOD AND APPARATUS FOR SHARING RADIO RESOURCES IN AN OFDM-BASED COMMUNICATION SYSTEM”, by Yunsong Yang, Jianmin Lu, and Anthony C. K. Soong; and U.S. Application Ser. No. 60/793,961, filed on Apr. 20, 2006, entitled “METHOD AND APPARATUS FOR SHARING RADIO RESOURCES USING MULTI-USER PACKET FORMAT AND SINGLE USER PACKET FORMAT IN AN OFDMA-BASED COMMUNICATION SYSTEM”, by Anthony C. K. Soong, Yunsong Yang, and Jianmin Lu; and U.S. Application Ser. No. 60/824,283, filed on Aug. 31, 2006, entitled “METHOD AND APPARATUS FOR SHARING RADIO RESOURCES IN A WIRELESS COMMUNICATIONS SYSTEM”, by Yunsong Yang, Anthony C. K. Soong, and Jianmin Lu; U.S. Application Ser. No. 60/829,526, filed on Aug. 31, 2006, entitled “METHOD AND APPARATUS FOR INDICATING THE RESOURCE THAT ARE VALID FOR SHARING IN AN OFDMA-BASED COMMUNICATION SYSTEM” by Anthony C. K. Soong, Jianmin Lu and Zhigang Rong; all of which are incorporated herein by reference as if reproduced in their entirety.
Number | Date | Country | |
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60895072 | Mar 2007 | US |