GB2461517A

GB2461517A - Method of managing a transmission mode of a wireless device

Info

Publication number: GB2461517A
Application number: GB0811960A
Authority: GB
Inventors: Sadia Quadri
Original assignee: Toshiba Research Europe Ltd
Current assignee: Toshiba Europe Ltd
Priority date: 2008-06-30
Filing date: 2008-06-30
Publication date: 2010-01-06
Anticipated expiration: 2028-06-30
Also published as: GB2461517B; GB0811960D0; JP2010016823A

Abstract

A method of managing a transmission mode of a wireless device in a wireless network having a plurality of wireless devices is carried out at the wireless device, and comprises receiving a signal transmitted at a particular transmission rate from a further wireless device, determining the transmission rate of the received signal, and managing the transmission mode of the wireless device in accordance with the determined transmission rate.

Description

WIRELESS COMMUNICATION METHOD AND APPARATUS

Field of the Invention

The present invention relates to wireless communication. It is particularly, but not exclusively, concerned with wireless communication between two or more communications devices, using a packet based standardised approach such as defined in the IEEE8O2. 11 family of standards.

Background of the Invention

Wireless communication between electronic devices is becoming increasingly in demand, particularly due to the growth of multimedia communication services, such as video streaming, video conferencing, packet data transfer and so on. Accordingly, wireless networks are widely deployed to support these services. Generally, these networks are capable of supporting communications for multiple users by sharing the available network resources. One example of such network is a wireless local area network (WLAN).

A typical arrangement of a WLAN 10 is illustrated in figure 1. Such a WLAN may include one or more access points (APs) 12, 14, 16 that serve one or more wireless devices (WD) 18. An AP (for example, 12) is typically a stand-alone device that is connected to an Ethernet switch (not shown) which can be in turn connected to a modem (not shown) to allow the wireless devices 18 to connect to the Internet. The AP 12 also bridges all data between the WDs 18a, 18b associated to it.

As shown in figure 1, two or more APs 12, 14, 16 may link together to form a larger network to allow the WDs 18 to roam from one WLAN lOa to another WLAN, for

example lOb or lOc.

The wireless devices (WDs) described herein may be mobile terminals such as personal digital assistants (PDAs), notebook computers, or fixed terminals such as desktops and workstations that are equipped with a wireless network interface.

Many WLAN standards allow for a number of different modes of operation to be available for use, depending on operating conditions. For instance, in conditions wherein little channel interference is encountered, a high speed, low robustness operating mode can be employed. In contrast, in conditions more susceptible to channel interference, a lower speed, more robust approach may need to be employed.

Most approaches to rate adaptation (adaptive modulation) are based on either the Received Signal Strength Indicator (RSS1) or historic information about the channel.

However, the condition of a wireless channel is not static and so a more realistic or real time knowledge of the channel condition can aid in improving the achievable throughput.

Specific algorithms with which present day wireless cards switch modes are implementation dependent. However, the only method of sending information back from the receiver to the transmitter is via the presence or absence of ACKs (acknowledgements).

The presence of an ACK at the transmitter means that the receiver received a transmitted DATA packet successfully. The absence of an ACK could mean one of the following: 1. The DATA frame was never received (e.g. deep fade) 2. The DATA frame was destructively interfered with.

3. The ACK frame was never received (e.g. deep fade) 4. The ACK frame was destructively interfered with.

There may also be other causes. Nonetheless, whatever the cause for packet failure, the transmitter responds by transmitting the DATA packet again but at a lower rate than in the previous transmission. The manner in which rate is adapted, such as in terms of the extent to which rate is lowered, or how rapidly rate is lowered, is implementation dependent.

An example of a data-control flow diagram representing transmissions between an AP and a WD (or herein referred to as node A and node B respectively) is illustrated in figure 2. In this example, node A 20 transmits a DATA packet 24 to node B 22 at a data rate ofx Mbps. Upon successful receipt of this packet, node B 22 responds with an ACK signal 26 transmitted at a rate ofy Mbps which is the BSS basic set rate as defined in Table 1 and Table 2. Typically, the BSS basic rate set is less than (or equal to) the data rate of the received packet.

In a communications system compliant with the 802.11 standard, the BSS Basic Rate Set is defined in accordance with Table 1 below.

Table 1

Name Type Valid range Description

BSSBasicRateSet Set of 1-127 The set of data rates (in integers inclusive (for units of 500kb/s) that must each integer be supported by all STAs in the set) that desire to join this BSS.

The STAs must be able to receive and transmit at each of the data rates listed in the ___________________ ___________ ______________ set.

The set of rates in 802.lla, b, g and n, specified as part of the BSS basic rate set are

given in Table 2.

Table 2

System BSS Basic Rate Set 802.1 la 6,12,24 Mbps 802.llb 1Mbps 802.llg 1,2,5.5,11,6,12,24Mbps 802.lln 6,9,12,18,24,36,48,54 Mbps As seen from Table 2, the 802.1 lb standard only defines one rate in the BSS basic rate set and so is not relevant to the presently described technical problems. However, all other present variations of 802.11 such as a, g and n (and future versions which may 4.

also employ more than one available transmission rate) standards are relevant to the

current disclosure.

By way of background, a conventional method for data transmission between two nodes A and B will now be described. In this example, the messages to be transmitted are 1000 bytes long using the 802.1 la transmission rates. It is understood that the transmission time required to transmit a DATA packet (for example, a packet of 1000 bytes) is dependent on the transmission rate, which can be represented by equation 1: T x Time Tpreamble + Tsignai + x Ceiling (16+8x length + 6)/Ndbps (1) Where Tpreamble 8ps Tsignai 4j.xs The list of transmission time required for transmitting 1000 bytes long packets according to 802.11 a standard is given in Table 4.

Table 4

Transmit time for 1000 byte 802.lla transmission rates Ndbps ______________________________ packets _____________ 54Mbps 172us 216 48Mbps 188 us 192 36Mbps 244 us 144 24Mbps 356 us 96 18Mbps 468 us 72 12Mbps 692us 48 9Mbps 912us 36 6Mbps 1340 us 24 Figure 3 shows an example of transmitting a total of six data packets of 1000 bytes each from node A 30 to node B 32. The data transmission commences by establishing a connection between the two nodes, in steps 34 and 36.

Once the connection between the two nodes is established, a first data packet (DATA1) is transmitted at 18Mbps from node A in step 38. Accordingly, an ACK signal is in turn transmitted (step 40) at 6 Mbps from node B to node A. As described in the preceding paragraphs, the presence of an ACK indicates that the transmission is successful.

Subsequently, DATA2 is transmitted at a higher rate (24Mbps) in step 42. In response, node B transmits an ACK signal at 6 Ivfbps in step 44 to indicate that a DATA2 has been successfully received. On positive receipt of the ACK signal, node A again decides to further increase the rate of transmission to 36 Mbps to transmit the subsequent data packet, DATA3 (step 46). However, due to interference, DATA3 is not delivered to node B. As a result, no ACK signal is received at node A, and therefore the packet (DATA3) is retransmitted at a lower data rate of 24 Mbps in step 48. At step 50 an ACK signal is transmitted from node B to node A in response to successful reception of DATA3.

Similarly, DATA4 and DATA5 are successfully transmitted at transmission rate of 36 Mbps (step 52) and 48 Mbps (step 56) respectively. As shown in steps 60 to 62, a transmission rate of 48 Mbps is required to transmit DATA6. In this example, a total of eight packets were transmitted over the air interface, and the total time required to send six data packets (DATA 1 to DATA6) successfully is 22l6ts.

The 802.11 standard states "To allow the transmitting STA to calculate the contents of the Duration ID field, the responding STA shall transmit its Control Response and Management Response frames (either CTS or ACK) at the highest rate in the BSS basic rate set that is less than or equal to the rate of the immediately previous frame in the frame exchange sequence (as defined in [1], 9.7). In addition, the Control Response frame shall be sent using the same PRY options as the received frame [1] (section 9.6)." However, the manner in which the transmitter increases the transmission rate is not addressed in the art. One approach is to employ a timer or a packet counter which, after a number of successful transmissions in a given mode, would induce the transmitter to increase the transmission rate (step by step). For example, EP1686753 discloses a method of controlling the transmission rate of an ACK (reception acknowledgement signal) based on the number of retransmissions of a user data frame. Essentially, the number of retransmitted frames is counted, and if this number is greater than a predetermined value M, (which indicates that the transmission quality of an ACK is poor) the ACK transmission rate is reduced by one level. Similarly, the number of successive successful frames is counted, and if this number is greater than a predetermined value N, (which indicates that the transmission quality is good) the ACK transmission rate is increased by one level. Therefore, the ACK transmission rate is independent of the rate of data transmission.

WO 2004/002049 discloses a method of providing signal quality feedback in a wireless network. A transmitter sends a data packet to a receiver at an initial transmission power and data transmission rate. The receiver receives the data packet in the data signal and determines a signal quality metric for the data signal. The receiver then sends an acknowledgement frame to the transmitter in an acknowledgement signal. The acknowledgement frame includes one or more feedback bits, which indicates a relative signal quality of the data signal. The transmitter receives the acknowledgement frame in the acknowledgement signal at the transmitter, and adjusts the transmission power and the data transmission rate based on the feedback bits.

Summary of the Invention

In a first aspect of the present invention there is provided a method of managing a transmission mode of a wireless device in a wireless network having a plurality of wireless devices, said method being performed at said wireless device in communication with at least one further wireless device of said plurality of wireless devices through a communication channel, and the method comprising receiving a signal transmitted at a transmission rate from said further wireless device, determining the transmission rate of said received signal, and managing said transmission mode of said wireless device based on said determined transmission rate.

An advantage of using the transmission rate of a received signal directly to manage the transmission mode of a wireless device is that no extra information is required to be received in order to manage the transmission mode of the wireless device, thereby preserving the spectrum efficiency of the channel.

The received signal may be an acknowledgement frame The acknowledgment frame may be in accordance with the IEEE 802.11 WLAN standard.

In one embodiment of the present invention, there is provided the step of converting the rate of transmission of the acknowledgment frame into an indication of the quality of the communication channel.

It will be appreciated that, in wireless communications, an acknowledgment frame (or ACK) is a signal passed between wireless devices to indicate successful transmission state when the wireless devices establish a communication link. Therefore, one of the benefits of using an ACK to indicate the quality of the communication channel is that no further signal is required to estimate the channel quality. It is noted that this approach makes efficient use of the available capacity of the network. It is further noted that this approach can allow the wireless device to use the most appropriate transmission mode to transmit subsequent data according to the operating condition of the communications between the wireless devices. Therefore, the achievable throughput of the communication channel between the wireless devices can be significantly improved.

The step of converting may include representing a plurality level of said channel quality by a corresponding plurality of data rates. For example, a transmission rate of 24 Jvfbps may represent a good channel quality, a transmission rate of 12 Mbps may represent a moderate channel quality, and a transmission rate of 6 Mbps may represent a poor quality channel.

The transmission mode may include a transmission rate of said wireless device.

The step of managing said transmission mode of said wireless device may include adjusting the transmission rate of said wireless device according to the transmission rate of said received acknowledgement frame. Therefore, this can allow the transmission rate of the wireless device to be adjusted to a lower rate if the transmission rate of the acknowledgement frame is for example, 6 Mbps, indicating a poor quality channel.

In a second aspect of the present invention there is provided a method of providing a feedback signal from a wireless device in a wireless network having a plurality of wireless devices to at least one further wireless device of said plurality of wireless devices, said wireless device being in conirnunication with said further wireless device through a communication channel, and the method comprising receiving a signal from said further wireless device, determining channel information associated with said signal, transmitting a feedback signal at a transmission rate to said further wireless device, and wherein said transmission rate is set based on said determined channel information.

The feedback signal may be an acknowledgement frame.

The acknowledgment frame may be in accordance with the IEEE 802.11 WLAN standard.

In one embodiment of the present invention, there is provided the step of converting the rate of transmission of the acknowledgment frame into an indication of the quality of* the communication channel.

The step of converting may include representing a plurality level of said channel quality by a corresponding plurality of data rates.

In a third aspect of the present invention there is provided an apparatus for managing a transmission mode of a wireless device in a wireless network having a plurality of wireless devices, said wireless device being in communication with at least one further wireless device of said plurality of wireless devices, the apparatus comprising means for receiving a signal transmitted at a transmission rate from said further wireless device, means for determining the transmission rate of said received signal, and means for managinging said transmission mode of said wireless device based on said determined transmission rate.

In a fourth aspect of the present invention there is provided an apparatus for providing a feedback signal from a wireless device in a wireless network having a plurality of wireless devices to at least one further wireless device of said plurality of wireless device, said wireless device being in communication with said further wireless device through a communication channel, the apparatus comprising means for receiving a signal from said further wireless device, means for determining channel information associated with said signal, means for transmitting a feedback signal at a transmission rate to said further wireless device, and wherein said transmission rate is set based on said determined channel information.

In a fifth aspect of the present invention there is provided a wireless communications system comprising a wireless network having a wireless device being in communication with at least one further wireless device, the wireless device being operable to transmit a signal in a first transmission mode to said further wireless device operable to receive said signal, said further wireless device being operable to determine channel information associated with said data signal, and to transmit a feedback signal at a transmission rate to said wireless device, wherein the transmission rate is set based on said determined channel information, the wireless device is further operable to receive said feedback signal, to determine the transmission rate of said feedback signal, and to transmit a further signal in a second transmission mode based on said determined transmission rate.

Aspects of the invention may comprise a computer program product comprising computer executable instructions operable to cause a computer to become configured to perform a method in accordance with any of the above identified aspects of the invention. The computer program product can be in the form of an optical disc or other computer readable storage medium, a mass storage device such as a flash memory, or a read only memory device such as RUM. The method may be embodied in an application specific device such as an ASIC, or in a suitably configured device such as a DSP or an FPGA. A computer program product could, alternatively, be in the form of a signal, such as a wireless signal or a physical network signal.

Brief description of the drawings

Embodiments of the present invention will now be described with reference to the accompanying drawings, wherein: Figure 1 illustrates an exemplary prior art WLAN arrangement; Figure 2 is a data control flow diagram illustrating data transmissions between two communication devices; Figure 3 is a data control flow diagram illustrating data transmissions between two communication devices in accordance with the prior art; Figure 4 is a schematic diagram of an example communications device; Figure 5 is a flow diagram illustrating a process of managing the transmission rate of a communication device in accordance with a first embodiment of the invention; and Figure 6 is a data control flow diagram illustrating data transmissions between two communication devices in accordance with the first embodiment of the invention.

Detailed Description

Specific embodiments of the present invention will be described in further detail on the basis of the attached diagrams. It will be appreciated that this is by way of example only, and should not be viewed as presenting any limitation on the scope of protection sought.

Figure 4 illustrates schematically a communication device 70 providing an example of background to the invention. In this example, the communication device is a wireless device 18 as illustrated in figure 1. The communication device 70 comprises a processor 72 operable to execute machine code instructions stored in a working memory 74 and/or retrievable from a mass storage device 76. By means of a general-purpose bus 78, user operable input devices 80 are in communication with the processor 72. The user operable input devices 80 comprise, in this example, a keyboard and a touchpad, but could include a mouse or other pointing device, a contact sensitive surface on a display unit of the device, a writing tablet, speech recognition means, haptic input means, or any other means by which a user input action can be interpreted and converted into data signals.

Audio/video output devices 82 are further connected to the general-purpose bus 78, for the output of information to a user. Audio/video output devices 82 include a visual display unit, and a speaker, but can also include any other device capable of presenting information to a user.

A communications unit 84 is connected to the general-purpose bus 78, and further connected to an antenna 86. By means of the communications unit 84 and the antenna 86, the communication device 70 is capable of establishing wireless communication with another communication device (for example, an AP). The communications unit 84 is operable to convert data passed thereto on the bus 78 to an RF signal carrier in accordance with a communications protocol previously established for use by a system in which the communication device 70 is appropriate for use.

In the communication device 70 of figure 4, the working memory 74 stores user applications 88 which, when executed by the processor 72, cause the establishment of a user interface to enable communication of data to and from a user. The applications 88 thus establish general purpose or specific computer implemented utilities arid facilities that might habitually be used by a user.

Referring to figure 5, the example commences in a situation whereby two communication devices, such as a WI) and an AP (or in this example are referred to as node A and node B respectively), establish a communication link between each other in step 90. In step 92, a DATA packet is transmitted at x Mbps from node A to node B. Upon successful receipt of the DATA packet, the channel information associated with the transmitted DATA is determined at node B (step 96). It will be understood that various methods of determining channel information such as those known in the art may be used. For example, use of iterative decoders that apply parity check sequences such as Low Density Parity Check (LDPC) or sequential decoding, in which the channel quality is proportional to the number of iterations performed by the decoder. These methods of determining channel information are not part of the present invention, and will not be discussed further.

In step 98, an ACK signal is transmitted at a transmission rate ofy Mbps from node B to node A. Conversely, through the absence of an ACK signal being received at node A which indicates that the DATA packet is not received by node B, node A will then retransmit the DATA packet at the same data rate (that is x Mbps).

The transmission rate y Mbps is set based on the detennined channel information as described in the previous paragraph. As an example, the data and ACK transmissions rates and the associated channel information are given in Table 5.

Referring to Table 5, if the data is transmitted at 54 Mbps from node A to node B, and depending on the determined channel quality, the ACK signal will be transmitted at an appropriate transmission rate. For example, if channel quality is poor, the ACK signal will be transmitted at 6 Mbps.

Once the ACK signal is received at node A (step 100), the channel information is determined based on the transmission rate of the ACK signal in step 102. This can be achieved by converting the rate of transmission of the acknowledgement frame into an indication of the quality of the communication channel. For example if the ACK signal is transmitted at 6 Mbps, node A will interpret the channel as poor quality and will decrease the transmission rate accordingly.

As shown in Figure 5, if the channel quality is good, the transmission data for transmitting a subsequent data packet will be increased (steps 104 and 106).

Conversely, if the channel quality is bad, the transmission data for transmitting a subsequent data packet will be decreased (steps 108 to 110). Otherwise, the transmission rate will remain unchanged (step 112).

Three levels of granularity for data rates above 18 Mbps are used in Table 5 as an example. However, it will be appreciated that other levels of granularity can also be.

applied. It will further be understood that the higher the number of levels of ACK transmission rate is used, the higher the granularity of the indication of the channel condition.

Table 5

Data rate for 802.11 a Possible ACK rate for Interpretation of channel _______________________ 802.lla info 54 Mbps 24 Mbps Good Channel can go higher ________________________ _________________________ if available 54 Mbps 12 Mbps Maintain same rate 54 Mbps 6 Mbps Bad channel condition consider lower for better ________________ ________________ QoS 48 Mbps 24 Mbps Good Channel can go higher ________________________ _________________________ if available 48 Mbps 12 Mbps Maintain same rate 48 Mbps 6 Mbps Bad channel condition consider lower for better ________________ ________________ QoS 36 Mbps 24 Mbps Good Channel can go higher _________________________ _________________________ if available 36 Mbps 12 Mbps Maintain same rate 36 Mbps 6 Mbps Bad channel condition consider lower for better ________________ ________________ QoS 24 Mbps 24 Mbps Good Channel can go higher _______________________ _______________________ if available 24 Mbps 12 Mbps Maintain same rate 24 Mbps 6 Mbps Bad channel condition consider lower for better _________________ _________________ QoS 18 Mbps 12 Mbps Good Channel can go higher _________________________ _________________________ if available 18 Mbps 6 Mbps Maintain same rate or try ______________________ ______________________ higher depending on RSSI 12 Mbps 12 Mbps Good Channel can go higher _________________________ _________________________ if available 12 Mbps 6 Mbps Maintain same rate or try _______________________ _______________________ higher depending on RSSI 9 Mbps 6 Mbps Maintain same rate or try higher rate depending on

_______________________ _______________________ RS SI

6 Mbps 6 Mbps Maintain same rate or try higher rate depending on

_______________________ _______________________ RSSI

The present invention will now be further described by way of an example. For consistency, the same example as used in figure 3 to describe the general approach applied in the prior art is used in this example to describe the present invention.

Similarly, in this example a total of six data packets of 1000 bytes each are transmitted from node A to node B. Referring to figure 6, node A 30 and node B 32 establish a communication link between each other in steps 120 and 122. Once the connection is established, a first data packet (DATA1) is transmitted at 18Mbps from node A in step 124. Accordingly, an ACK signal is in turn transmitted at 12 Mbps in step 126 from node B to node A to indicate that the transmission is successful. At this stage, node A can decide to either maintain at the same transmission rate (18 Mbps) or to increase the transmission rate depending on the RSSI value of the ACK signal.

Subsequently, DATA2 is transmitted at a higher rate (24Mbps) in step 128. In response, node B transmits an ACK signal at 12 Mbps to indicate that although a DATA2 has been successfully received, the received signal was noisy and node B might not be able to decode it if the data transmission rate is increased. Therefore, in the case, the data rate remains at the same rate, that is 24 Mbps. Consequently, DATA3 is also transmitted at 24 Mbps in step 132. In response, the ACK signal is transmitted at 24 Mbps in step 134 to indicate that the channel condition is good, and therefore the data transmission rate can be increased.

Similarly, DATA4 and DATA5 are transmitted at an increased data transmission rate in steps 136 and 140. However, the ACK signal transmitted in response to DATA5 indicates that the channel is noisy, and increasing the transmission rate of the subsequent data packet (DATA6) might cause the transmission to fail. As a result, DATA6 is transmitted at the same data rate as DATA5 (step 144).

The example illustrated in the foregoing paragraphs clearly demonstrates the key advantage of the present invention in that the total time required to transmit six data packets is 1 800 jis, which is significantly less than that using the approach demonstrated in the prior art. This is useful in applications such as VoW (Voice Over Internet Protocol) and video streaming applications, as delays in packet transmissions can affect the quality of service (QoS) for these applications.

As described in the prior art example, lower data transmission rates tends to be applied to ensure that data are being transmitted, as lower data rates are more reliable. This has a significant disadvantage in that this approach results in unnecessary throughput loss when the channel can allow data to be transmitted at a higher transmission rate.

Conversely, the present invention effectively improves the utilisation of the communications channel bandwidth since it supports the use of higher transmission rates.

It will be understood that the invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Each feature disclosed in the description and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Claims

CLAIMS: I. A method of managing a transmission mode of a wireless device in a wireless network having a plurality of wireless devices, said method being performed at said wireless device in communication with at least one further wireless device of said plurality of wireless devices through a communication channel, and the method comprising receiving a signal transmitted at a transmission rate from said further wireless device; determining the transmission rate of said received signal; and managing said transmission mode of said wireless device based on said determined transmission rate.
2. A method according to claim 1 wherein the received signal is an acknowledgement frame.
3. A method according to claim 2 further comprising the step of converting the rate of transmission of the acknowledgment frame into an indication of the quality of the communication channel.
4. A method according to claim 3 wherein the step of converting includes representing a plurality level of channel quality by a plurality of corresponding data rates.
5. A method according to any one of the preceding claims wherein the transmission mode includes a transmission rate of said wireless device.
6. A method according to claim 5 wherein the step of managing said transmission mode of said wireless device includes adjusting the transmission rate of said wireless device according to the transmission rate of said received acknowledgement frame.
7. A method of providing a feedback signal from a wireless device in a wireless network having a plurality of wireless devices to at least one further wireless device of said plurality of wireless devices, said wireless device being in communication with said further wireless device through a communication channel, and the method comprising receiving a signal from said further wireless device; determining channel information associated with said signal; transmitting a feedback signal at a transmission rate to said further wireless device; and wherein said transmission rate is set based on said determined channel information.
8. A method according to claim 7 wherein the received signal is an acknowledgement frame.
9. A method according to claim 8 further comprising the step of converting the rate of transmission of the acknowledgment frame into an indication of the quality of the communication channel.
10. A method according to claim 9 wherein the indication of the quality of the communication channel includes representing a plurality level of channel quality by a corresponding plurality of data rates.
11. An apparatus for managing a transmission mode of a wireless device in a wireless network having a plurality of wireless devices, said wireless device being in communication with at least one further wireless device of said plurality of wireless devices through a communication channel, the apparatus comprising means for receiving a signal transmitted at a transmission rate from said further wireless device; means for determining the transmission rate of said received signal; and means for managing said transmission mode of said wireless device based on said determined transmission rate.
12. An apparatus according to claim 11 wherein the received signal is an acknowledgement frame.
13. An apparatus according to claim 12 further comprising means for converting the rate of transmission of the acknowledgment frame into an indication of the quality of the communication channel.
14. An apparatus according to claim 13 wherein the indication of the quality of the communication channel includes representing a plurality level of channel quality by a plurality of corresponding data rates.
15. An apparatus according to any one of claims 11 to 14 wherein the transmission mode includes a transmission rate of said wireless device.
16. An apparatus according to claim 15 wherein the means for managing said transmission mode of said wireless device is operable to adjust the transmission rate of said wireless device according to the transmission rate of said received acknowledgement frame.
17. An apparatus for providing a feedback signal from a wireless device in a wireless network having a plurality of wireless devices to at least one further wireless device of said plurality of wireless device, said wireless device being in communication with said further wireless device through a communication channel, the apparatus comprising means for receiving a signal from said further wireless device; means for determining channel information associated with said signal; means for transmitting a feedback signal at a transmission rate to said further wireless device; and wherein said transmission rate is set based on said determined channel information.
18. An apparatus according to claim 17 wherein the received signal is an acknowledgement frame
19. An apparatus according to claim 18 further comprising means for converting the rate of transmission of the acknowledgment frame into an indication of the quality of the conununication channel.
20. An apparatus according to claim 19 wherein the indication of the quality of the communication channel includes representing a plurality level of channel quality by a plurality of corresponding data rates.