Quality of service provisioning using periodic channel time allocation

This application enjoys the priority of the earlier US patent application US60 / 659612 filed on March 8, 2004, and the teachings of that US application are incorporated herein by reference.

Wireless communication bandwidth has increased significantly with advances in channel modulation technology, making wireless media a viable alternative to wired and fiber optic solutions. As such, the use of wireless connections in data and voice communications continues to grow. These devices are not only audio / visual streaming, video / audio telephones, fixed computers for wireless networks, and portable handset, but also mobile phones, wireless networks (eg wireless local area networks (WLANs)), to name a few. ) Including portable computers.

Each wireless network includes multiple layers and sub-layers, such as a media access control (MAC) sub-layer and a physical (PHY) layer. The MAC layer is subordinate to the two sublayers of the data link layer in the Open Systems Interconnection (OSI) stack. The MAC layer provides coordination among many users who require simultaneous access to the same wireless media.

The MAC layer protocol includes multiple rules that control access to broadcast media shared by users within the network. As is known, several different multiple access technologies (often referred to as the MAC protocol) are specified to operate within the protocol that manages the MAC layer. These include, but are not limited to, carrier sense multiple access (CSMA), frequency division multiple access (FDMA), and time division multiple access (TDMA).

Standards and protocols provide significant improvements in controlling voice and data traffic, but while supporting quality of service (QoS) requirements, the continued increase in demand for network access at increasing channel rates It requires continuous evaluation of protocols and standards, as well as changes to them. For example, many known protocols (published as ECMA Standard 368) such as WiMedia Ultra Wideband (UWB) MAC 1.0, and other non-slot-based WLANs such as IEEE 802.11 have QoS requirements from applications. Needs to be communicated to the lower layers of the network stack based on the application stream traffic specification (TSPEC). Upon receiving the TSPEC of the application stream, the lower layer, such as the MAC, allocates resources to supply the traffic stream that meets the QoS requirements. In various MAC protocols, one such resource is the airtime available for the transmission of data or other information. Providing QoS in these wireless MAC protocols typically relates to, for example, allocating airtime according to the QoS requirements specified in TSPEC. For example, in slot-based MAC protocols such as WiMedia UWB MAC, there are various aspects of allocating media access slots (MAS) (eg, media access time) that result in differences in characteristics such as delay and power savings.

Allocation of consecutive blocks of airtime for the transmission of data or airtime can lead to the maximum service interval for the application stream. This can lead to a large permissible delay time (bound). However, because it is evenly distributed, a smaller time allocation for data transmission over a course of superframes requires the transmitter to "start" frequently. Each activation takes 200-300 μs, or time equivalent to one MAS. This is only a low power saving performance. Moreover, a large number of smaller, distributed pieces of time allocation over the course of the superframe may not allow the transmission of the entire packet to be successful. In addition, requesting an allocated piece of MAS for data transmission within a superframe increases the amount of overhead. The overhead can be, for example, MAC interframe space (IFS), packetization delay, and if there is not enough transmission time at the edge of the superframe, the transmitter will follow in order to send the entire packet. You will have to wait during the interval.

<p> Therefore, there is a need for methods and systems that significantly overcome the shortcomings of at least the known methods described.</p>

<p> According to one example aspect, the method of allocating media access time in a wireless network is to determine the periodic service interval of the application stream based on TSPEC, delay requirement specifications, and local resources, and the low latency of the application stream. A step that defines a category and a high-efficiency category, a step that categorizes the application stream into one of the low-latency category or the high-efficiency category based on a determined periodic service interval, and a step that categorizes the application stream. Has a step of allocating media access time within a periodic service interval based on.</p><p> In one embodiment, the defined step includes setting a threshold for a periodic service interval.</p><p> In one embodiment, the categorizing step includes determining whether the periodic service interval exceeds a threshold.</p><p> In one embodiment, when the assigning step categorizes periodic service intervals into low latency categories, media access slots are evenly distributed across superframes in each of the plurality of allocation zones available for transmission. Has a step of spreading.</p><p> In one embodiment, the assigning step includes a step of assigning consecutive MAS when categorized into periodic service intervals and high efficiency categories.</p><p> In one embodiment, the step of uniformly spreading the MAS across the superframe comprises assigning the location of the media access slot within a particular portion of the two-dimensional display of the superframe.</p><p> In one embodiment, the step of assigning consecutive MAS includes the step of assigning the location of the media access slot within a particular portion of the two-dimensional display of the superframe.</p><p> In one embodiment, the method of allocating media access time in a wireless network is to determine the periodic service interval for each of at least two application streams based on the TSPEC, latency requirements, and local resources of each application stream. And, based on the steps that define the low latency category and the high efficiency category for all application streams, and the determined periodic service interval, each of at least two application streams is placed in the low latency category, or It has a step of categorizing into one of the high efficiency categories and a step of allocating the media access time within the superframe based on the step of categorizing.</p><p> In one embodiment, the assigning step further comprises maximizing the distance in the two-dimensional display of the superframe between the low latency category application stream and the high efficiency category application stream.</p><p> In one aspect, the system that allocates media access slots includes multiple wireless devices. Each of the wireless devices includes a transmitter for transmitting a signal, a receiver for receiving a signal, a processor, and a power supply, and the processor is based on the TSPEC of the application stream, delay requirement specifications, and local resources. The periodic service interval is determined, the low-latency category and the high-efficiency category of the application stream are defined, and the application stream is classified as one of the low-latency category or the high-efficiency category based on the determined periodic service interval. It is categorized into one, and the media access time is allocated in the super frame based on the categorization.</p><p> The present invention is best understood from the following detailed description when read with the accompanying drawings. It is emphasized that the various features are not always scaled. In fact, the size may be optionally scaled up or down for clarity of discussion.</p>

In the following detailed description, exemplary embodiments that disclose specific details for descriptive and non-limiting purposes are described to provide a thorough understanding of the exemplary embodiments. However, those skilled in the art who benefit from the present disclosure will be aware of other embodiments that deviate from the particular details disclosed herein. Moreover, the description of well-known devices, methods, systems and protocols may be omitted to clarify the description of the present invention. Nevertheless, such devices, methods, systems, and protocols that are within the knowledge of those skilled in the art may be used by one embodiment. Finally, in the practical case, the same kind of reference code refers to the same kind of feature.

Briefly, descriptive examples describe methods and systems for improving efficiency and throughput in distributed wireless networks. The method and system calculates the maximum service interval that will meet the TSPEC and delay requirement specifications of one or more application streams. This is achieved, for example, by allocating a continuous MAS (ie, a portion of the media access time) to minimize power loss due to many "boot" operations.

According to the exemplary embodiments described here, distributed (ie, slot-based) wireless networks operate on WiMedia MAC 1.0. Of course, this is merely descriptive, and other MAC protocols may incorporate sharing of device availability within the networks described in connection with the exemplary embodiments. These include, but are not limited to, the results of current WiMedia MAC protocols as well as other carrier-sense multiple access / collision avoidance (CSMA / CA) or time division multiple access (TDMA) protocols. .. Further, the examples described herein may also be applied to WLANs with non-slot based media access, such as IEEE 802.11 WLANs. It is emphasized that these protocols are merely descriptive and that other protocols known to those of skill in the art may be implemented by embodiments.

FIG. 1 is a schematic diagram of a wireless network system that includes multiple wireless devices or systems that share (ie, coexist) communication media, according to an example embodiment. The wireless device / system 101 may transmit or receive (or transmit) traffic 104 to or from another wireless device within its transmission range 102. Further, there may be other wireless devices / systems 103 that are outside the range 102 of one wireless device / system 101 but within the range of one device 101'. The wireless device 101 includes a transceiver 110 (eg, any known transmitter / receiver combination, or a separate transmitter and receiver), a processor 111 (eg, any known device that processes a bit of information), and a power supply 112. Includes (eg battery).

FIG. 2 is a superframe timeline 200 between the first beacon 201 and the second beacon 202. Here, the start point of the beacon is referred to as the beacon section start time (BPST), and there is a defined section between the beacons. In one example embodiment, the superframe is divided into a plurality of media access slots (MAS) 203 to provide organized transmission and reception for the exemplary embodiment. In a descriptive embodiment, there are 256 slots 203, each slot having a duration of about 256 μs, and the total duration of the superframe is about 65.536 ms in the exemplary embodiment (thus between BPSTs). 65.536ms). Of course, the number and duration of slot 203 is for illustration purposes only and is not a limitation of slot 203 at all.

At the start of each superframe 200, there is a beacon interval 204. To be clearer as we continue this discussion, the Beacon Interval 204, in addition to requiring the device / system to send traffic to the other devices / systems in the wireless network 100 of the example embodiment, A means of communication for sharing availability information of devices / systems of network 100 (eg, devices 101, 103) is provided.

After the beacon interval 204 is the service interval 206. Each service interval has a certain number of slots. Different application streams require a different number of slots 203 to ensure proper media access for the transmission of complete packets. The processor at the transmitter determines how long the service interval is required to send the data packet. This decision is made by analyzing the bandwidth requirements, delay requirement specifications, and TSPEC of the application stream. In addition, the service interval is periodic (ie, occurs over several cycles of beacon interval 204 and service interval 206).

To calculate the periodic service interval, the processor (eg, processor 111 in FIG. 1) calculates the service rate g according to local resources such as buffer size and TSPEC. The local resource may be, for example, the buffer space and media time required by the transmitter transmitting the data in the operating MAC. The processor uses the calculated g to cause the queue delay d caused by the burst size of the application stream._qAlso calculate. The maximum service interval 206 can be calculated based on the delay requirement specifications. Slot-based media access mechanisms such as WiMedia UWB can be calculated as follows: SI d_s-d_qHere d_sIs a delay requirement specification, d_qIs the additional queue delay caused by the burst size of the application stream.

FIG. 3 illustrates a two-dimensional display of the Superframe 200. On the y-axis of the display, MAS gradually increases downward. The x-axis of the display is the allocation zone that increases horizontally (ie, from left to right in the drawing). Allocation zones 1 to 15 represent continuous MAS grouping. MAS with x = 2 and y = 1 sequentially follow MAS with x = 1 and y = 15 in time. According to the prior art, the input application stream has been pre-allocated to a high efficiency method or a low latency method depending on the application method requirements and the QoS requirements of the MAC. In the low latency scheme, the data transmission is a MAS slot (eg row component) where (x = 1, y = 15), (x = 2, y = 15), ..., (x = 15, y = 15). ) Only. In FIG. 3, block 302 illustrates a low latency scheme for MAS allocation. This method starts every 4.096ms, for example, and allows only one MAS at most for each start for transmission. This requires power for each start-up and can be inefficient due to overhead.

Consecutive MAS blocks are used for highly efficient methods. The example in FIG. 3 illustrates data transmission in MAS slots with x = 4, y = {0, ..., 7} and x = 12, y = {0, ..., 7}. These contiguous MAS blocks provide reduced power by requiring less orbital motion and include less overhead risk. Blocks 303, 303'in FIG. 3 illustrate a high efficiency method for MAS allocation.

Both high efficiency and low latency schemes (or categories) are for MAS allocation based on, for example, a minimum delay requirement specification of at least 4 ms, or power consumption or media utilization efficiency requirements for a minimum reserved block length. , It is necessary to coexist in the super frame with equal support given to both.

As an example, WiMedia UWB MAC 1.0 requires 256 MAS superframes structured into 16 allocated zones (eg, the x-axis of Figure 3) and 16 row components (eg, the y-axis of Figure 3). This requires coordination between the high efficiency scheme required by the application stream and the low latency scheme required by the same application stream or additional application streams. One possible policy is to 1) strictly apply the low latency allocation to each of the individual subsets of the 16-line component. An example of this could allocate individual streams across row components at either end of the allocation zone (eg, the portion of 15MAS where x = {2 ... 15} and y = 15).

2) Remove the equal allocation limit for the rest of the row components (eg, a contiguous portion of MAS in the allocation that decreases along the x-axis that is not in the previous subset of row components). This allows the determination of whether the periodic service interval required by the device exceeds the threshold 301, thereby requiring an even distribution of MAS across all row components.

3) If the periodic service interval of a particular application stream requires MAS allocation above the threshold 301, this requires a highly efficient method and MAS is contiguous in a subset of the available allocation zones. Assigned to a block. The MAS should in this case be assigned to the allocation zone on the opposite side of the 2D superframe display in order to maximize the continuous available MAS between the high efficiency and low latency schemes.

There can be two devices with different application streams that you want to send to the same superframe. Each application stream will have a periodic service interval that may require either high efficiency or low latency schemes. In this case, the periodic service interval for each application stream must be determined from each of its TSPECs. Each periodic service interval is categorized as high efficiency or low latency, and the MAS allocates the opposite side of the 2D superframe display to maximize the consecutively available MAS between the two schemes. Assigned within the zone. A multi-dimensional stream that requires a highly efficient scheme can also be a MAS allocated in an individual allocation zone or in an alternative allocation zone.

Maximizing the continuously available MAS between low-latency and high-efficiency schemes ensures power savings and minimal overhead risk without compromising support for low-latency applications. ..

FIG. 4 illustrates a flow chart of a method of allocating media access time in a wireless network. In step 401, the processor determines a periodic service interval based on the application stream transmission standard (TSPEC), delay requirement specifications, and local resources. This decision can also be made for multiple application streams with multiple characteristics. In step 402, the processor defines a method of high efficiency and low latency. This specification may be stored in the processor, set in a look-up table, or specified in any other aspect of the prior art. In step 403, depending on power sensing and MAS availability, the processor categorizes the application stream as high efficiency or low latency. The processor then assigns a MAS, during which the transmitter may transmit data based on the categorization in step 404.

FIG. 5 illustrates an additional substep of step 404. In step 501, the processor categorizes the periodic service intervals into low latency categories and allocates media access slots uniformly across superframes in each of the plurality of allocation zones available for transmission. In step 502, the processor allocates contiguous media access slots when the periodic service intervals are categorized into high efficiency categories. In step 503, the processor evenly distributes the media access slots across the superframe by allocating the media access slot locations within a specific portion of the two-dimensional display of the superframe for the low latency category application stream. Let me. In step 504, the processor allocates contiguous media access slots for specific parts of the superframe two-dimensional display for the high efficiency category application stream. Steps 501-504 may occur individually in step 404 or in any temporal order. Some of steps 501-504 do not have to occur at all.

In view of this disclosure, it is not that the various methods and devices described herein are implemented with known hardware and software to achieve efficient media access and sharing in distributed wireless networks. Be careful. Moreover, the various methods and parameters are merely included by way of example and do not imply any limitation. In view of this disclosure, those skilled in the art will determine, within the scope of the claims, their technology and the equipment required to achieve these techniques. The method can be realized.

<figref num="1">FIG. 1 is a diagram of a wireless communication network system sharing media according to an example embodiment.</figref><figref num="2">FIG. 2 is a superframe timeline according to an example example.</figref><figref num="3">FIG. 3 is a two-dimensional display of the super frame.</figref><figref num="4">Figure 4 shows how information is transmitted over a wireless network.</figref><figref num="5">Figure 5 shows how to allocate MAS in a superframe.</figref>