Abstract:
Systems and methods are provided to increase data throughput by aggregating block acknowledgements. Embodiments of these systems and methods provide a single block acknowledgement for multiple traffic identifiers in data communication with a communication station. One method includes providing a multiple start sequence number corresponding to each traffic identifier of a plurality of traffic identifiers and providing a bit map corresponding to each multiple start sequence number. The bit map indicates a block acknowledgement of packets corresponding to one traffic identifier of the plurality of traffic identifiers.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to wireless local area network (WLAN) technology. More particularly, the present invention relates to a increasing data throughput using a block acknowledgement. 
     2. Description of the Related Art 
     This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section. 
     Recently, there has been a great increase in the use of wireless local area networks (WLANs) conforming to the IEEE 802.11 communication standard. WLANs are expected to support the same applications as wired networks that they replace or supplement. The IEEE 802.11e group is developing media access control (MAC) improvements to support quality of service (QoS) sensitive applications, to enable a better mobile user experience, and to make more efficient use of the wireless channel. 
       FIG. 1  illustrates a prior art communication frame  2  for non-quality of service (QoS) acknowledgements. The communication frame  2  includes a frame control field  3 , a duration/ID field  4 , a Receiver Address (RA) field  5 , and a FCS (frame check sequence) field  6 . 
     The 802.11e specification includes a variety of optional features. One of the optional features is known as block acknowledgements (Block ACK). The legacy 802.11 MAC always sends an ACK frame after each frame that is successfully received. Block ACK allows several data frames to be transmitted before an ACK is returned, which increases the efficiency since every ACK frame has a significant overhead for transmission. Block ACK is initiated through a setup and negotiation process between the Quality of Service station (QSTA) and Quality of Service Access Point (QAP). Once the block ACK has been established, multiple quality of service (QoS) data frames can be transmitted in a contention free burst, with short inter-frame space (SIFS) separation between the frames. 
     Currently, there are two block ACK mechanisms defined under 802.11e: immediate and delayed. When using immediate block ACK, the sending station transmits multiple data frames in a contention free burst, separated by SIFS. The sender must obey the constraints of the transmit opportunities (TXOP) duration it is currently operating within. At the end of the burst, the sender transmits a block ACK request frame. The receiver must immediately respond with a block ACK frame containing the acknowledgement status for the previous burst of data frames. 
     The delayed policy allows the group acknowledgement to be sent in a subsequent TXOP following the burst. The same sequence of a contention free burst and block ACK request is used as in the immediate mode. The receiver simply sends a standard ACK in response to the block ACK request, indicating that the block ACK will be delayed. Delayed acknowledgement increases the latency, and is provided to support lower performance implementations that are unable to immediately calculate the ACK. 
       FIG. 2  illustrates a prior art communication frame for quality of service (QoS) data block acknowledgement. This block acknowledgement is defined in the IEEE 802.11e specification. The block acknowledgement (ACK) structure acknowledges frames within on traffic identifier (TID). The Block ACK acknowledges a block of frames with one signaling message. Nevertheless, the Block ACK is applicable to only one communication traffic stream, identified by a traffic identifier (TID). A traffic stream is a stream of data (e.g., voice and best effort data) associated with a certain traffic specification. The starting sequence control provides a sequence number of the frames starting from the receiver which need to send a block acknowledgement. Every subsequent frame is indicated as a bit in the bitmap. A zero (0) in the bitmap indicates no received and a one (1) in the bitmap means received. 
     Thus, there is a need to enhance the Block ACK function by aggregating block ACK for different TIDs for a communication station so that it can be applicable to multiple traffic streams. In this way, a communication station with multiple applications can use just one Block ACK instead of requiring a Block ACK for each traffic identifier (TID). Further, there is a need to aggregate multiple frames from different traffic identifiers (TID) to enable the sending of an aggregated block ACK per communication station for multiple TIDs. 
     SUMMARY OF THE INVENTION 
     One exemplary embodiment relates to a method of providing a single block acknowledgement for multiple traffic identifiers in data communication with a communication station. The method includes providing a multiple start sequence number corresponding to each traffic identifier of a plurality of traffic identifiers and providing a bit map corresponding to each multiple start sequence number. The bit map indicates a block acknowledgement of packets corresponding to one traffic identifier of the plurality of traffic identifiers. 
     As a result of the exemplary embodiments, a station responds with one ACK when it receives multiple frames aggregated together, instead of multiple ACKs. The exemplary embodiments are applicable to both immediate and delayed ACK cases. It is possible to do aggregation of regular ACK, delayed Block ACKs, and immediate Block ACKs in any combination. 
     Another exemplary embodiment relates to a system for providing a single block acknowledgement for multiple traffic identifiers in data communication with a communication station. The system includes a transmit opportunity including quality of service data and short inter-frame spaces and a block acknowledgement structure including a multiple start sequence number for each of a plurality of traffic identifiers and a corresponding bit map indicating acknowledgement of packets corresponding to one traffic identifier of the plurality of traffic identifiers. 
     Another exemplary embodiment relates to a device configured for communication in a wireless local area network (WLAN) with a data throughput including aggregated block acknowledgements. The device includes a memory configured to contain a block acknowledgement structure and a processor that communicates the block acknowledgement structure to indicate receipt of data. The block acknowledgement structure includes a multiple start sequence number for each of a plurality of traffic identifiers and a corresponding bit map indicating acknowledgement of packets corresponding to one traffic identifier of the plurality of traffic identifiers. 
     Another exemplary embodiment relates to a computer program product that increases data throughput by aggregating block acknowledgements to a single block acknowledgement for a plurality of traffic identifiers in a communication system. The computer program product includes computer code to assign a start sequence number for each of a plurality of traffic identifiers, wherein each start sequence number is associated with a bit map indicating acknowledgment status for the corresponding traffic identifier; and computer code to provide a block acknowledgment control field for each of the plurality of traffic identifiers. 
     Yet another exemplary embodiment relates to a block acknowledgment structure including a multiple start sequence number for each of a plurality of traffic identifiers and a corresponding bitmap indicating acknowledgement of packets corresponding to one traffic identifier of the plurality of traffic identifiers. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram depicting a communication frame for non-quality of service (QoS) data acknowledgement. 
         FIG. 2  is a diagram depicting a communication frame including a block acknowledgement feature. 
         FIG. 3  is a diagram depicting a communication frame including a block acknowledgement feature in accordance with an exemplary embodiment. 
         FIG. 4  is a diagram depicting a communication frame including an aggregated block acknowledgement feature for non-QoS data in accordance with an exemplary embodiment. 
         FIG. 5  is a diagram depicting an exemplary communication session involving the block acknowledgement feature of  FIG. 3 . 
         FIG. 6  is a diagram depicting a communication system including the block acknowledgement feature of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 3  illustrates a communication frame  10  including a block acknowledgment feature for a communication station (STA). The block acknowledgement acknowledges frames for all traffic identifiers (TIDs) currently served through a communication station (STA). The communication frame  10  is made up of a number of data communication fields. According to an exemplary embodiment, the communication frame  10  includes a frame control field  12 , a duration field  14 , a RA (Receiver Address) field  16 , and a TA (Transmitter Address) field  18 . 
     For TID number  1 , there is a block ACK control field  22 , a block ACK starting sequence control field  24 , and a block ACK bitmap field  26 . Fields for additional TIDs can be included. For illustration purposes, TID-n represents the highest numbered TID. TID-n can be represented by block ACK control field  28 , block ACK starting sequence control field  30 , and block ACK bitmap field  32 . The communication frame  10  can include FCS (frame check sequence) field  34 . 
     Where a number of TIDs exist, there are more than one block ACK control fields, block ACK starting sequence control fields, and block ACK bitmap fields included in the structure. In an alternative embodiment, a number TID field  20  can be included that stores a value for the number of TIDs. The duration field  14  can indicate the length of the communication frame  10 . 
     The multiple starting sequence fields (one for each TID) and a corresponding bit map indicating the ACK/block ACK of packets corresponding to the TID allows for aggregation of block ACK for different TIDs. As a result, a station with multiple applications can use one block ACK instead of requiring a block ACK for each access category. The block ACK control field  22  carries the traffic identifier (TID). The block ACK starting sequence control field  24  has two parts, sequence number and the fragment number. The block ACK bitmap field  26  indicates the receiving status of the frames where a value of one (1) means the frame is received successfully and a value of zero (0) means the frame is not received successfully. The position in bitmap is added to the starting sequence control to determine location in communication frame. 
       FIG. 4  illustrates a communication frame  35  including a block acknowledgment feature. The communication frame  35  includes non QoS data. The communication frame  35  is made up of a number of data communication fields, such as a frame control field  36 , a duration field  37 , a RA (Receiver Address) field  38 , a block ACK starting sequence control field  39 , a block ACK bitmap field  40 , and a FCS (frame check sequence) field  41 . 
     The communication frame  35  illustrates that the exemplary embodiments extend non-QoS STA or non-QoS AP. In the non-QoS case, the aggregated block ACK carries only one instance of sequence number and the sequence bitmap. There is no need for carrying a traffic identifier (TID) or a number of TID. 
     Sending of one ACK for a set of frames creates a single point of failure. In other words, if this one ACK is lost, the sender needs to retransmit all the outstanding frames waiting for ACK. Advantageously, according to an exemplary embodiment, the aggregated block ACK is communicated with a more robust coding over the air, increasing the chance of successful transmission of the aggregated block ACK. One option for the station is to send the aggregated block ACK with more robust coding than the current ability of the station. Another option is to send the aggregated block ACK with the best coding ability. 
     Accordingly to an exemplary embodiment, the aggregated Block ACK has an identification for the receiver. It can have different sub types (i.e. class to identify communication frame) in the control frame so the receiver can recognize it. It can be default feature with another feature, e.g. High Throughput Frame Aggregation capability. As a result, the presence of frame aggregation implies presence of aggregated block ACK. It can also be an optional feature negotiated between transmitter and receiver. 
       FIG. 5  illustrates an exemplary communication session involving the block acknowledgement feature described with reference to  FIG. 1 . In the communication session  40 , three traffic identifiers are used TID=1, TID=2, and TID=3. The traffic identifiers correspond to transmit opportunities with quality of service data communicated during the opportunities. As would be understood by a person of skill in the art, Quality of Service (QoS) refers to the capability of a network to provide better service to selected network traffic over various technologies. 
     A common block acknowledgement request  42  is utilized by the communication streams of multiple traffic identifiers. The common block acknowledgement request  42  results in a single block acknowledgement  44  in return. As example of a block acknowledgement is described with reference to  FIG. 3 . As a result, data throughput in the communication network is improved. Instead of three acknowledgement requests and three acknowledgements, one acknowledgement request and one acknowledgement are communicated. 
     A wireless local area network (WLAN) system offers a range of data rates, such as 6, 9, 12, 18, 24, 36, 48, and 54 Mbps in 802.11a systems. A data rate is set for a station (STA) based on its current modulation and coding scheme (MCS), which in turn is governed by the STA&#39;s radio environment. A lower data rate offers better error protection than a higher data rate. For example, chances of a successful frame transmission with 18 Mbps is greater than frame transmission with 24 Mpbs. However, at the same time a STA uses maximum possible data rate based on its current radio conditions. The sending of one aggregated block ACK for a set of frames creates a single point of failure. In other words, if this one ACK is lost, the sender needs to retransmit all the outstanding frames waiting for ACK. As a result, in an exemplary embodiment, the aggregated block ACK is communicated at a lower data rate (or higher error protection), thereby increasing the chance of successful transmission. One optional implementation is for the STA to send the aggregated block ACK with one rate level lower then the current ability of the STA. For example, if the STA is capable of 18 Mbps, then it sends aggregated block ACK with 12 Mbps. Another option is to send the aggregated block ACK with the lowest data rate, i.e. 6 Mbps. 
       FIG. 6  illustrates a communication system  50  including the block ACK feature described herein. The exemplary embodiments described herein can be applied to any telecommunications system. Communication system  50  includes a terminal equipment (TE) device  52 , an access point (AP)  54 , a server  56 , and a network  58 . The TE device  52  can include memory (MEM), a central processing unit (CPU), a user interface (UI), and an input-output interface (I/O). The memory can include non-volatile memory for storing applications that control the CPU and random access memory for data processing. The I/O interface can include a network interface card of a wireless local area network, such as one of the cards based on the IEEE 802.11 standards. 
     The TE device  52  can be connected to the network  58  (e.g., a local area network (LAN), the Internet, a phone network) via the access point  54  and further to the server  56 . The TE device  52  can also communicate directly with the server  56 , for instance using a cable, infrared, or a data transmission at radio frequencies. The server  56  can provide various processing functions for the TE device  52 . 
     The TE device  52  can be any portable electronic device, in which speech recognition is performed, for example a personal digital assistant (PDA) device, remote controller or a combination of an earpiece and a microphone. The TE device  52  can be a supplementary device used by a computer or a mobile station, in which case the data transmission to the server  56  can be arranged via a computer or a mobile station. In an exemplary embodiment, the TE device  52  is a mobile station communicating with a public land mobile network, to which also the server  56  is functionally connected. The TE device  52  connected to the network  58  includes mobile station functionality for communicating with the network  58  wirelessly. The network  58  can be any known wireless network, for instance a network supporting the GSM service, a network supporting the GPRS (General Packet Radio Service), or a third generation mobile network, such the UMTS (Universal Mobile Telecommunications System) network according to the 3GPP (3 rd  Generation Partnership Project) standard. The functionality of the server  56  can also be implemented in the mobile network. The TE device  56  can be a mobile phone used for speaking only, or it can also contain PDA (Personal Digital Assistant) functionality. 
     While several embodiments of the invention have been described, it is to be understood that modifications and changes will occur to those skilled in the art to which the invention pertains. The invention is not limited to a particular embodiment, but extends to various modifications, combinations, and permutations that nevertheless fall within the scope and spirit of the appended claims.