Acknowledging data transmissions in the presence of multiple shared-communications channels

CROSS-REFERENCE TO RELATED APPLICATIONS

0001This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/469,263, entitled “Variable-Width Modulation Schemes Featuring Backward-Compatible Local Area Network Operation,” filed on May 9, 2003, which is incorporated by reference.

FIELD OF THE INVENTION

0002The present invention relates to telecommunications in general, and, more particularly, to local area networks.

BACKGROUND OF THE INVENTION

0003<figref idref="DRAWINGS">FIG. 1</figref> depicts a schematic diagram of a portion of wireless local area network <b>100</b> in the prior art. Local area network <b>100</b> comprises legacy stations <b>101</b>-<b>1</b> through <b>101</b>-K, wherein K is a positive integer, and enhanced stations <b>102</b>-<b>1</b> through <b>102</b>-L, wherein L is a positive integer. Legacy stations <b>101</b>-<b>1</b> through <b>101</b>-K and enhanced stations <b>102</b>-<b>1</b> through <b>102</b>-L use shared-communications medium <b>103</b> to communicate among themselves. Shared-communications medium <b>103</b> comprises multiple shared-communications channels. Only one of the stations can transmit into a given channel at a time, although one of the stations can transmit into a first channel while another station transmits into a second channel.

0004When two stations transmit into a given channel at the same time, the result is a cacophony and both transmissions are garbled. Prior art techniques, such as Carrier Sense Multiple Access, are used by the stations to coordinate when each of them transmits over a single shared-communications channel.

0005Legacy stations <b>101</b>-<b>1</b> through <b>101</b>-K can transmit and receive using: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0006">i. a modulation scheme that uses one shared-communications channel at a time (i.e., a single-channel modulation scheme). <br /> In contrast, enhanced stations <b>102</b>-<b>1</b> through <b>102</b>-L can transmit and receive using: </li><li id="ul0001-0002" num="0007">i. a modulation scheme that uses one shared-communications channel at a time (i.e., a single-channel modulation scheme), and</li><li id="ul0001-0003" num="0008">ii. a modulation scheme that uses multiple shared-communications channels simultaneously (i.e., a multi-channel modulation scheme).</li></ul>

0009Any two stations that need to communicate must do so in accordance with a modulation scheme that is available to both of them. Therefore, two enhanced stations can communicate with each other by using a multi-channel modulation scheme, but any communication involving a legacy station must use a single-channel modulation scheme.

0010Enhanced stations <b>102</b>-<b>1</b> and <b>102</b>-<b>2</b>, for example, communicate with each other by using the multi-channel modulation scheme when possible because it enhances communication throughput in comparison to the single-channel modulation scheme. One effect of using the multi-channel modulation scheme, however, is that legacy station <b>101</b>-<b>1</b>, for example, cannot detect when enhanced stations <b>102</b>-<b>1</b> and <b>102</b>-<b>2</b> are communicating (i.e., enhanced stations <b>102</b>-<b>1</b> and <b>102</b>-<b>2</b> are essentially undetectable by legacy station <b>101</b>-<b>1</b> when enhanced stations <b>102</b>-<b>1</b> and <b>102</b>-<b>2</b> are communicating by using the multi-channel modulation scheme). This can cause legacy station <b>101</b>-<b>1</b> to transmit when enhanced stations <b>102</b>-<b>1</b> and <b>102</b>-<b>2</b> are communicating, which causes all of the transmissions to be garbled.

0011Even if enhanced station <b>102</b>-<b>1</b> successfully transmits the data block to enhanced station <b>102</b>-<b>2</b>, enhanced station <b>102</b>-<b>2</b> might subsequently have difficulty transmitting an acknowledgment of the data block back to enhanced station <b>102</b>-<b>1</b>. The difficulty in transmitting the acknowledgment is attributed to the same reason of enhanced nodes being undetectable that was described earlier. In the event of an unsuccessful acknowledgment transmission, enhanced station <b>102</b>-<b>1</b> has to re-transmit the data block in its entirety.

0012What is needed is a way to improve data transmission over multiple shared-communications channels without some of the performance disadvantages in the prior art.

SUMMARY OF THE INVENTION

0013The present invention provides a technique that improves the efficiency of transmitting data over multiple shared-communications channels without some of the costs and disadvantages associated with techniques in the prior art. In particular, and in accordance with the illustrative embodiment of the present invention, a data frame is simultaneously transmitted across a plurality of channels, but the acknowledgment frame to the data frame is not. Instead, a plurality of redundant acknowledgment frames are generated and each one is transmitted independently and within each of the channels used to transmit the data frame.

0014For example, a single data frame is transmitted across two channels, and a redundant acknowledgment frame is transmitted in each of the two channels in legacy mode. Although a single acknowledgment frame could be transmitted across the two channels, the transmission of redundant acknowledgment frames in each channel is advantageous because it increases the likelihood that the acknowledgment will be received. The likelihood that the acknowledgment will be received is increased in accordance with the present invention because the acknowledgment will be received even when one of the channels is unusable, whereas the disruption of either channel would prevent the reception of an acknowledgment frame that spans two channels.

0015When the likelihood that the acknowledgment will be received is increased, the number of unnecessary data retransmissions is reduced, which saves channel bandwidth.

0016The station receiving the acknowledgment, in some embodiments, can take action based on (i) the contents of the received acknowledgment frame or frames and (ii) the channel or channels over which the acknowledgment was received. For example, depending on the indications provided in a received acknowledgment and the channel over which the acknowledgment was received, the station might decide to re-transmit some of the data block or the entire data block over one or more shared-communications channels, or the station might decide that a re-transmission is unnecessary.

0017In some embodiments of the present invention, before transmitting the data frame, a station transmits a control frame (e.g., a clear_to_send frame, etc.) into each communications channel to ensure that the communications channel is available. The multiple control frames specify a duration value that protects the subsequent transmission over multiple channels.

0018An illustrative embodiment of the present invention comprises: receiving a first portion of a data block on a first shared-communications channel; receiving a second portion of the data block on a second shared-communications channel; transmitting a first acknowledgment frame into the second shared-communications channel only, wherein the first acknowledgment frame indicates receipt of the first portion of the data block; and transmitting a second acknowledgment frame into the first shared-communications channel only, wherein the second acknowledgment frame indicates receipt of the second portion of the data block.

BRIEF DESCRIPTION OF THE DRAWINGS

0019<figref idref="DRAWINGS">FIG. 1</figref> depicts a schematic diagram of wireless local area network <b>100</b> in the prior art.

0020<figref idref="DRAWINGS">FIG. 2</figref> depicts a schematic diagram of a portion of network <b>200</b> in accordance with the illustrative embodiment of the present invention.

0021<figref idref="DRAWINGS">FIG. 3</figref> depicts a block diagram of the salient components of station <b>203</b>-j in accordance with the illustrative embodiment of the present invention.

0022<figref idref="DRAWINGS">FIG. 4</figref> depicts a flowchart of the salient tasks performed in accordance with the first illustrative embodiment of the present invention.

0023<figref idref="DRAWINGS">FIG. 5</figref> depicts a message flow diagram in accordance with the first illustrative embodiment of the present invention.

0024<figref idref="DRAWINGS">FIG. 6</figref> depicts a flowchart of the salient tasks performed in accordance with the second illustrative embodiment of the present invention.

0025<figref idref="DRAWINGS">FIG. 7</figref> depicts a message flow diagram in accordance with the second illustrative embodiment of the present invention.

DETAILED DESCRIPTION

0026<figref idref="DRAWINGS">FIG. 2</figref> depicts a schematic diagram of network <b>200</b> in accordance with the illustrative embodiment of the present invention. Network <b>200</b> operates in accordance with the IEEE 802.11 set of protocols and comprises legacy stations <b>201</b>-<b>1</b> through <b>201</b>-M, wherein M is a positive integer; legacy host computers <b>202</b>-<b>1</b> through <b>202</b>-M; enhanced stations <b>203</b>-<b>1</b> through <b>203</b>-N, wherein N is a positive integer; host computers <b>204</b>-<b>1</b> through <b>204</b>-N; and wireless communications medium <b>205</b>, interconnected as shown. Wireless communications medium <b>205</b> comprises shared-communications channels <b>206</b>-<b>1</b> through <b>206</b>-P.

0027It will be clear to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention that operate in accordance with other protocols. Furthermore, it will be clear to those skilled in the art, after reading this specification, how to make and use embodiments of the present invention that use a wireline or tangible communications medium.

0028Legacy station <b>201</b>-i, for i=1 through M, comprises the radios that enable legacy host computer <b>202</b>-i to communicate via communications medium <b>205</b> by using a single shared-communications channel <b>206</b>-k at a time, wherein k is a value between 1 and P, inclusive. Legacy station <b>201</b>-i is capable of receiving data blocks from legacy host computer <b>202</b>-i and transmitting over communications medium <b>205</b> data frames comprising the data received from legacy host computer <b>202</b>-i. Legacy station <b>201</b>-i is also capable of receiving data frames from shared communications channel <b>205</b> and sending to legacy host computer <b>202</b>-i data blocks comprising data from the data frames. It will be clear to those skilled in the art how to make and use legacy station <b>201</b>-i.

0029Legacy host computer <b>202</b>-i is capable of generating data blocks and transmitting those data blocks to legacy station <b>201</b>-i. Legacy host computer <b>202</b>-i is also capable of receiving data blocks from legacy station <b>201</b>-i and of processing and using the data contained within those data blocks. Legacy host computer <b>202</b>-i can be, for example, a desktop or a laptop computer that uses network <b>200</b> to communicate with other hosts and devices. It will be clear to those skilled in the art how to make and use legacy host computer <b>202</b>-i.

0030Enhanced station <b>203</b>-j (or, concisely, “station” <b>203</b>-j), for j=1 through N, comprises the radios that enable host computer <b>204</b>j to communicate via communications medium <b>205</b> by using one or more of shared-communications channels <b>206</b>-<b>1</b> through <b>206</b>-P at a time. Station <b>203</b>-j is capable of receiving data blocks from host computer <b>204</b>-j and transmitting over communications medium <b>205</b> data frames comprising the data received from host computer <b>204</b>-j. Station <b>203</b>-j is also capable of receiving data frames from shared communications channel <b>205</b> and sending to host computer <b>204</b>-j data blocks comprising data from the data frames. It will be clear to those skilled in the art, after reading this specification, how to make and use station <b>203</b>-j. The salient details for station <b>203</b>-j are described below and with respect to <figref idref="DRAWINGS">FIG. 3</figref>.

0031Host computer <b>204</b>-j is capable of generating data blocks and transmitting those data blocks to station <b>203</b>-j. Host computer <b>204</b>-j is also capable of receiving data blocks from station <b>203</b>-j and of processing and using the data contained within those data blocks. Host computer <b>204</b>-j can be, for example, a desktop or a laptop computer that uses network <b>200</b> to communicate with other hosts and devices. It will be clear to those skilled in the art how to make and use host computer <b>204</b>-j.

0032In some embodiments, station <b>203</b>j, wherein j is equal to a value between 1 and N, inclusive, is an access point as is known in the art. Station <b>203</b>j, when functioning as an access point, enables other stations <b>203</b>-<b>1</b> through <b>203</b>-N within network <b>200</b> to communicate with devices in other communications networks. Furthermore, stations <b>203</b>-<b>1</b> through <b>203</b>-N communicate with each other through the access point, because the access point can be used to coordinate communications on network <b>200</b>.

0033Communications medium <b>205</b> comprises one or more shared-communications channels <b>206</b>-k, for k=1 through P. Shared-communications channel <b>206</b>-k exists in a variety of forms. For example, each shared-communications channel <b>206</b>-k can correspond to a given block of frequency spectrum out of multiple blocks, contiguous or otherwise. It will be clear to those skilled in the art how to allocate one or more shared-communications channels <b>206</b>-k, for k=1 through P.

0034<figref idref="DRAWINGS">FIG. 3</figref> depicts a block diagram of the salient components of station <b>203</b>-j in accordance with the illustrative embodiment of the present invention. Station <b>203</b>-j comprises receiver <b>301</b>-j, processor <b>302</b>-j, memory <b>303</b>-j, and transmitter <b>304</b>-j, interconnected as shown.

0035Receiver <b>301</b>-j is a circuit that is capable of receiving frames from one or more of shared-communications channels <b>206</b>-<b>1</b> through <b>206</b>-P, in well-known fashion, and of forwarding them to processor <b>302</b>-j. It will be clear to those skilled in the art how to make and use receiver <b>301</b>-j.

0036Processor <b>302</b>-j is a general-purpose processor that is capable of performing the tasks described below and with respect to <figref idref="DRAWINGS">FIGS. 4 through 7</figref>. It will be clear to those skilled in the art, after reading this specification, how to make and use processor <b>302</b>-j.

0037Memory <b>303</b>-j is capable of storing programs and data used by processor <b>302</b>-j. It will be clear to those skilled in the art how to make and use memory <b>303</b>-j.

0038Transmitter <b>304</b>-j is a circuit that is capable of receiving frames from processor <b>302</b>-j, in well-known fashion, and of transmitting them on one or more of shared-communications channels <b>206</b>-<b>1</b> through <b>206</b>-P. It will be clear to those skilled in the art how to make and use transmitter <b>304</b>-j.

0039<figref idref="DRAWINGS">FIG. 4</figref> depicts a flowchart in accordance with the first illustrative embodiment of the present invention. In the example depicted, station <b>203</b>-<b>1</b> exchanges frames with station <b>203</b>-<b>2</b>. It will be clear to those skilled in the art, after reading this specification, how to make and use stations that exchange frames in the manner depicted.

0040For pedagogical purposes, two shared-communications channels are used throughout the examples in this specification. It will be clear, however, to those skilled in the art, after reading this specification, how to apply the illustrative embodiment of the present invention to two or more shared-communications channels.

0041At task <b>401</b>, in some embodiments, station <b>203</b>-<b>1</b> transmits a first control frame on shared-communications channel <b>206</b>-<b>1</b> in well-known fashion. In some embodiments, the first control frame is a request_to_send frame or a clear_to_send frame, as is known in the art. It will be clear to those skilled in the art how to make and use a control frame.

0042Station <b>203</b>-<b>1</b>, in some embodiments, also transmits a second control frame on shared-communications channel <b>206</b>-<b>2</b>. In some embodiments, the second control frame is a request_to_send frame or a clear_to_send frame, as is known in the art.

0043Station <b>203</b>-<b>1</b>, in some embodiments, transmits the first and second control frame at substantially the same time. Transmitting the first and second control frame at substantially the same time and with the duration fields set to an effective value has the effect of protecting a pending data block transmission that utilizes both shared-communications channel <b>206</b>-<b>1</b> and <b>206</b>-<b>2</b>. It will be clear to those skilled in the art how to set the duration field to a value that is effective in covering the time interval of a subsequent data transmission. In this specification, control frames transmitted in this fashion are referred to as providing “stacked protection.”

0044At task <b>402</b>, station <b>203</b>-<b>1</b> transmits to station <b>203</b>-<b>2</b> a first portion of a data block on shared-communications channel <b>206</b>-<b>1</b>, in well-known fashion.

0045At task <b>403</b>, station <b>203</b>-<b>1</b> transmits to station <b>203</b>-<b>2</b> a second portion of the data block on shared-communications channel <b>206</b>-<b>2</b>, in well-known fashion. In some embodiments, the first portion corresponds to the part of a multi-channel-modulated signal that utilizes shared-communications channel <b>206</b>-<b>1</b>, while the second portion corresponds to the part of the same multi-channel-modulated signal that utilizes shared-communications channel <b>206</b>-<b>2</b>. Stated differently, the first portion and the second portion constitute the same modulated signal. In other embodiments, the first portion corresponds to a first collection of bits constituting a data block, while the second portion corresponds to a second collection of bits constituting the same data block. It will be clear to those skilled in the art how to allot portions of a data block across multiple shared-communications channels in other ways.

0046Station <b>203</b>-<b>1</b>, in some embodiments, transmits the first portion and the second portion of the data block at substantially the same time.

0047At task <b>404</b>, station <b>203</b>-<b>2</b> receives the first portion of the data block.

0048At task <b>405</b>, station <b>203</b>-<b>2</b> receives the second portion of the data block.

0049At task <b>406</b>, station <b>203</b>-<b>2</b> transmits to station <b>203</b>-<b>1</b> a first acknowledgment frame on shared-communications channel <b>206</b>-<b>2</b>. The first acknowledgment frame comprises an indication of having received (i) the first portion of the data block, (ii) the second portion of the data block, or (iii) both. In other embodiments, the first acknowledgment frame comprises an indication of having received either (i) all of the transmitted portions of the data block or (ii) not all of the transmitted portions of the data block. It will be clear to those skilled in the art how to provide the indication in the first acknowledgment frame.

0050At task <b>407</b>, station <b>203</b>-<b>2</b> transmits to station <b>203</b>-<b>1</b> a second acknowledgment frame on shared-communications channel <b>206</b>-<b>1</b>. The second acknowledgment frame comprises an indication of having received (i) the first portion of the data block, (ii) the second portion of the data block, or (iii) both. It will be clear to those skilled in the art how to provide the indication in the second acknowledgment frame.

0051Station <b>203</b>-<b>2</b>, in some embodiments, transmits the first acknowledgment frame and second acknowledgment frame at substantially the same time.

0052At task <b>408</b>, station <b>203</b>-<b>1</b> receives the first acknowledgment frame.

0053At task <b>409</b>, station <b>203</b>-<b>1</b> receives the second acknowledgment frame.

0054In some embodiments, station <b>203</b>-<b>1</b> transmits an additional portion of the data block after receiving one or both of the first and second acknowledgment frames. Station <b>203</b>-<b>1</b>, in some embodiments, transmits the additional portion of the data block on one shared-communications channel <b>206</b>-k (e.g., shared-communications channel <b>206</b>-<b>1</b>, etc.). In other embodiments, station <b>203</b>-<b>1</b> transmits the additional portion of the data block on more than one shared-communications channel <b>206</b>-k.

0055<figref idref="DRAWINGS">FIG. 5</figref> depicts a message flow diagram in accordance with the first illustrative embodiment of the present invention. In the two examples depicted, station <b>203</b>-<b>1</b> exchanges frames with station <b>203</b>-<b>2</b>. It will be clear to those skilled in the art, after reading this specification, how to make and use stations that exchange frames in the manner depicted.

0056In the first example, station <b>203</b>-<b>1</b> transmits clear_to_send control frames <b>501</b> and <b>502</b> in well-known fashion. Each of control frames <b>501</b> and <b>502</b> specify a duration value as is known in the art that protects the pending transmission of a data block on shared-communications channel <b>206</b>-<b>1</b> and concurrently on shared-communications channel <b>206</b>-<b>2</b>.

0057Station <b>203</b>-<b>1</b> then transmits to station <b>203</b>-<b>2</b> data block <b>503</b> using both shared-communications channels <b>206</b>-<b>1</b> and <b>206</b>-<b>2</b>.

0058Upon receiving data block <b>503</b>, station <b>203</b>-<b>2</b> transmits to station <b>203</b>-<b>1</b> acknowledgment frames <b>504</b> and <b>505</b> in well-known fashion. Acknowledgment frames <b>504</b> and <b>505</b> each comprise an indication of the channel or channels on which data block <b>503</b> was received.

0059In the second example, station <b>203</b>-<b>1</b>, an access point in this example, transmits poll frames <b>506</b> and <b>507</b> in well-known fashion. Each of poll frames <b>506</b> and <b>507</b> specify a duration value as is known in the art that protects the pending transmission of a data block on shared-communications channel <b>206</b>-<b>1</b> and concurrently on shared-communications channel <b>206</b>-<b>2</b>.

0060Station <b>203</b>-<b>1</b> then transmits to station <b>203</b>-<b>2</b> data block <b>508</b> using both shared-communications channels <b>206</b>-<b>1</b> and <b>206</b>-<b>2</b>.

0061Upon receiving data block <b>508</b>, station <b>203</b>-<b>2</b> transmits to station <b>203</b>-<b>1</b> acknowledgment frames <b>509</b> and <b>510</b> in well-known fashion. Acknowledgment frames <b>509</b> and <b>510</b> each comprise an indication of the channel or channels on which data block <b>508</b> was received.

0062<figref idref="DRAWINGS">FIG. 6</figref> depicts a flowchart in accordance with the second illustrative embodiment of the present invention. In the example depicted, station <b>203</b>-<b>3</b> processes frames in accordance with the illustrative embodiment.

0063At task <b>601</b>, station <b>203</b>-<b>3</b> receives an acknowledgment after having transmitted a data block via both shared-communications channels <b>206</b>-<b>1</b> and <b>206</b>-<b>2</b>. The acknowledgment indicates receipt of at least one portion of the data block on (i) shared-communications channel <b>206</b>-<b>1</b>, (ii) shared-communications channel <b>206</b>-<b>2</b>, or (iii) both.

0064At task <b>602</b>, station <b>203</b>-<b>3</b> evaluates the received acknowledgment. Station <b>203</b>-<b>3</b> checks if the acknowledgment was received on both channels or one channel. Station <b>203</b>-<b>3</b> checks each acknowledgment frame received for an indication of the channel or channels over which the data block was successfully received.

0065At task <b>603</b>, station <b>203</b>-<b>3</b> re-transmits a portion of the data block. Station <b>203</b>-<b>3</b> re-transmits on one of or both shared-communications channels <b>206</b>-<b>1</b> and <b>206</b>-<b>2</b>. In accordance with the illustrative embodiment of the present invention, station <b>203</b>-<b>3</b> chooses the channel or channels over which to re-transmit based on the evaluation performed at task <b>602</b>.

0066<figref idref="DRAWINGS">FIG. 7</figref> depicts a message flow diagram in accordance with the second illustrative embodiment of the present invention. In the two examples depicted, station <b>203</b>-<b>3</b> exchanges frames with station <b>203</b>-<b>4</b> in accordance with the illustrative embodiment.

0067In the first example depicted, station <b>203</b>-<b>3</b> transmits data block <b>701</b> to station <b>203</b>-<b>4</b> in well-known fashion. Data block <b>701</b> comprises a first portion that is transmitted on shared-communications channel <b>206</b>-<b>1</b> and a second portion that is transmitted on shared-communications channel <b>206</b>-<b>2</b>.

0068Station <b>203</b>-<b>4</b> receives the first portion of data block <b>701</b> on shared-communications channel <b>206</b>-<b>1</b>. As part of the example, station <b>203</b>-<b>4</b> does not receive the second portion of data block <b>701</b>. Station <b>203</b>-<b>4</b> transmits to station <b>203</b>-<b>3</b> first acknowledgment frame <b>702</b> indicating that has received the first portion of data block <b>701</b>.

0069Acknowledgment frame <b>702</b> comprises fields that are used to indicate receipt of the corresponding portions of data. For instance, the fields can indicate the particular portion of data received, the shared-communications channel over which the portion was received, etc.

0070Station <b>203</b>-<b>3</b> then receives first acknowledgment frame <b>702</b> on shared-communications channel <b>206</b>-<b>1</b> from station <b>203</b>-<b>4</b>. Station <b>203</b>-<b>3</b> determines that it only received an acknowledgment frame (i.e., acknowledgment frame <b>702</b>) on shared-communications channel <b>206</b>-<b>1</b> and that received acknowledgment frame <b>702</b> indicated that only the first portion of data block <b>701</b> was received by station <b>203</b>-<b>4</b> and on shared-communications channel <b>206</b>-<b>1</b>.

0071Consequently, station <b>203</b>-<b>3</b> re-transmits the second portion of data block <b>701</b>, in the form of data block <b>703</b>, on shared-communications channel <b>206</b>-<b>1</b>. Station <b>203</b>-<b>3</b> bases this decision on the contents of received acknowledgment <b>702</b> and on the shared-communications channel on which acknowledgment <b>702</b> was received (i.e., shared-communications channel <b>206</b>-<b>1</b>).

0072In the second example depicted, station <b>203</b>-<b>3</b> transmits data block <b>704</b> to station <b>203</b>-<b>4</b> in well-known fashion. Data block <b>704</b> comprises a first portion that is transmitted on shared-communications channel <b>206</b>-<b>1</b> and a second portion that is transmitted on shared-communications channel <b>206</b>-<b>2</b>.

0073The difference of the second example from the first example is that station <b>203</b>-<b>4</b> receives the second portion of data block <b>704</b> on shared-communications channel <b>206</b>-<b>2</b>. Also, station <b>203</b>-<b>4</b> does not receive the first portion of data block <b>704</b>. Station <b>203</b>-<b>4</b> transmits to station <b>203</b>-<b>3</b> first acknowledgment frame <b>705</b> indicating that it has received the second portion of data block <b>704</b>.

0074Station <b>203</b>-<b>3</b> then receives first acknowledgment frame <b>705</b> on shared-communications channel <b>206</b>-<b>1</b> from station <b>203</b>-<b>4</b>. Station <b>203</b>-<b>3</b> determines that it only received an acknowledgment frame (i.e., acknowledgment frame <b>705</b>) on shared-communications channel <b>206</b>-<b>1</b> and that received acknowledgment frame <b>705</b> indicated that only the second portion of data block <b>704</b> was received by station <b>203</b>-<b>4</b> and on shared-communications channel <b>206</b>-<b>2</b>.

0075Consequently, station <b>203</b>-<b>3</b> re-transmits the first portion of data block <b>704</b>, in the form of data block <b>706</b>, using both shared-communications channels <b>206</b>-<b>1</b> and <b>206</b>-<b>2</b>. Station <b>203</b>-<b>3</b> bases this decision on the contents of received acknowledgment <b>705</b> and on the shared-communications channel on which the acknowledgment was received (i.e., shared-communications channel <b>206</b>-<b>1</b>).

0076It will be clear to those skilled in the art that other outcomes are possible, with respect to re-transmitting portions of data blocks based on the contents of an acknowledgment, the shared-communications channel on which the acknowledgment was received, and other conditions.

0077It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. For example, in this Specification, numerous specific details are provided in order provide a thorough description and understanding of the illustrative embodiments of the present invention. Those skilled in the art will recognize, however, that the invention can be practiced without one or more of those details, or with other methods, materials, components, etc.

0078Furthermore, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments. It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that a particular feature, structure, material, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the present invention, but not necessarily all embodiments. Consequently, the appearances of the phrase “in one embodiment,” “in an embodiment,” or “in some embodiments” in various places throughout the Specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.