Abstract:
Briefly, in accordance with one or more embodiments, a subscriber station in sleep mode is capable of sending and/or receiving traffic during sleep mode without violating the delay requirements of best effort traffic. Moreover, a subscriber station is capable of remaining in sleep and may optionally only be awaken in the event there is data to be transmitted from the base station to the subscriber station and/or from the subscriber station to the base station. By implementing an always sleep and need based wake up arrangement, the power consumption of the subscriber station can be reduced.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 60/918,792 filed Mar. 19, 2007. 
    
    
     BACKGROUND 
     In wireless networks, sleep mode is designed to reduce the power consumption by subscriber stations in the network. While in sleep mode, a subscriber station (SS) may alternate between an availability interval (AI) and an unavailability interval (UAI). During an unavailability interval an SS may power down its radio interface(s). On the other hand, during an availability interval, the subscriber station can communicate with the base station to send and/or receive data or management traffic. Thus, a subscriber station may send and/or receive traffic while in a sleep mode. However, the amount of traffic that can be exchanged and the delay associated with it depends on the duration and frequency of the availability interval. This is because the traffic can be exchanged between a subscriber station in sleep mode and a base station only during an availability interval. This is not a problem for real time traffic that is periodic in nature. For real time traffic such as voice over internet protocol (VoIP) traffic, traffic may arrive once in every T seconds. Moreover, the amount of traffic in every T seconds may be generally constant. Therefore, a subscriber station in sleep mode can easily send and/or receive such traffic by aligning its availability intervals to the arrival time of the traffic. Moreover, as the traffic length is more or less constant, the duration of the availability interval may be selected to allow the transfer of the expected amount of traffic. 
     On the other hand, the support of best effort (BE) traffic in sleep mode may be an issue. Two parameters may be defined to characterize such traffic: traffic load (TL) and delay requirements (DR) of the BE traffic. Based on these two parameters, BE traffic can be broadly classified into the following four groups. 
     Class A: BE traffic with low TL and less stringent DR 
     Class B: BE traffic with low TL and stringent DR 
     Class C: BE traffic with high TL and less stringent DR 
     Class D: BE traffic with high TL and stringent DR 
     A subscriber station in sleep mode can send and/or receive Class A BE traffic using the AI intervals. However, the subscriber station may not be able to send and/or receive other BE traffic classes using the AI intervals. Thus, the following two issues are considerations for supporting best effort traffic with higher traffic loads and/or stringent delay requirements in sleep mode. 
     The latency of the BE traffic (Class B and D) should be kept as low as possible. Therefore, waiting to transmit data only during AI may not be ideal, especially when the duration of AI is small. In a scenario in which the base station has to send X amount of data to a subscriber station in sleep mode, the base station waits until the next AI of the subscriber station and during the next AI the base station could send only Y (&lt;X) amount of data allowed by the length of AI interval, and waits to transmit the remaining (X-Y) amount of data until the another AI. This increases the delay in sending the total X amount of data. Such delay can be greater when the duration of UAI is long. 
     Uncontrolled growth of the buffered amount of BE traffic at the base station and/or the subscriber station when the subscriber station is in sleep mode should be avoided. Thus, sleep mode should support optional mechanisms for the subscriber station to send and/or receive any amount of traffic during its AI interval. Using such option, a subscriber station in sleep mode could send and/or receive traffic without terminating its sleep mode operation. As a result, the overhead associated with repeated trigger/termination of sleep mode could be reduced, and further power saving at the subscriber station could be increased. A subscriber station in sleep mode could retain the option to terminate its sleep mode to send and/or receive traffic. 
    
    
     
       DESCRIPTION OF THE DRAWING FIGURES 
       Claimed subject matter is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, such subject matter may be understood by reference to the following detailed description when read with the accompanying drawings in which: 
         FIG. 1  is block diagram of a wireless network in accordance with one or more embodiments; 
         FIG. 2  is a timeline diagram showing the utilization of a pseudo unavailability interval during which a subscriber station may send and/or receive traffic during a sleep mode in accordance with one or more embodiments; 
         FIG. 3  is a flow diagram of a method for transferring information between a base station and a subscriber station in sleep mode via a pseudo unavailability interval in accordance with one or more embodiments; 
         FIG. 4  is a flow diagram of a method for transferring information between a base station and a subscriber station in sleep mode via a pseudo unavailability interval where the pseudo unavailability interval may be longer than the next unavailability interval to accommodate larger amounts of data to be transferred in accordance with one or more embodiments; 
         FIG. 5  is a block diagram of an information handling system capable of optimizing a sleep mode operation in a wireless network in accordance with one or more embodiments; and 
         FIG. 6  depicts one embodiment of the subject matter disclosed herein that comprises an article of manufacture. 
     
    
    
     It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements. 
     DETAILED DESCRIPTION 
     In the following detailed description, numerous specific details are set forth to provide a thorough understanding of claimed subject matter. However, it will be understood by those skilled in the art that claimed subject matter may be practiced without these specific details. In other instances, well-known methods, procedures, components and/or circuits have not been described in detail. 
     In the following description and/or claims, the terms coupled and/or connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical and/or electrical contact with each other. Coupled may mean that two or more elements are in direct physical and/or electrical contact. However, coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate and/or interact with each other. For example, “coupled” may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements. Furthermore, the term “and/or” may mean “and”, it may mean “or”, it may mean “exclusive-or”, it may mean “one”, it may mean “some, but not all”, it may mean “neither”, and/or it may mean “both”, although the scope of claimed subject matter is not limited in this respect. In the following description and/or claims, the terms “comprise” and “include,” along with their derivatives, may be used and are intended as synonyms for each other. 
     Referring now to  FIG. 1 , a block diagram of a wireless network in accordance with one or more embodiments will be discussed. As shown in  FIG. 1 , network  100  may be an Internet Protocol (IP) type network comprising an Internet  110  type network or the like that is capable of supporting mobile wireless access and/or fixed wireless access to Internet  110 . In one or more embodiments, network  100  may be in compliance with a Worldwide Interoperability for Microwave Access (WiMAX) standard or future generations of WiMAX, and in one particular embodiment may be in compliance with an Institute for Electrical and Electronics Engineers 802.16e standard (IEEE 802.16e). In one or more alternative embodiments, network  100  may be in compliance with a Third Generation Partnership Project Long Term Evolution (3GPP LTE) or a 3GPP2 Air Interface Evolution (3GPP2 AIE) standard. In general, network  100  may comprise any type of orthogonal frequency division multiple access (OFDMA) based wireless network, and the scope of the claimed subject matter is not limited in these respects. As an example of mobile wireless access, access service network (ASN)  112  is capable of coupling with base station (BS)  114  to provide wireless communication between subscriber station (SS)  116  and internet  110 . Subscriber station  116  may comprise a mobile-type device or information-handling system capable of wirelessly communicating via network  100 , for example a notebook-type computer, a cellular telephone, a personal digital assistant, or the like. ASN  112  may implement profiles that are capable of defining the mapping of network functions to one or more physical entities on network  100 . Base station  114  may comprise radio equipment to provide radio-frequency (RF) communication with subscriber station  116 , and may comprise, for example, the physical layer (PHY) and media access control (MAC) layer equipment in compliance with an IEEE 802.16e-type standard. Base station  114  may further comprise an IP backplane to couple to Internet  110  via ASN  112 , although the scope of the claimed subject matter is not limited in these respects. 
     Network  100  may further comprise a visited connectivity service network (CSN)  124  capable of providing one or more network functions including, but not limited to, proxy and/or relay-type functions, for example, authentication, authorization and accounting (AAA) functions, dynamic host configuration protocol (DHCP) functions, or domain-name service controls or the like, domain gateways, such as public-switched telephone network (PSTN) gateways or Voice-over-Internet protocol (VOIP) gateways, and/or Internet Protocol (IP) type server functions, or the like. However, these are merely example of the types of functions that are capable of being provided by visited CSN or home CSN  126 , and the scope of the claimed subject matter is not limited in these respects. Visited CSN  124  may be referred to as a visited CSN in the case, for example, in which visited CSN  124  is not part of the regular service provider of subscriber station  116 , for example, in which subscriber station  116  is roaming away from its home CSN, such as home CSN  126 , or, for example, in which network  100  is part of the regular service provider of subscriber station, but in which network  100  may be in another location or state that is not the main or home location of subscriber station  116 . In a fixed wireless arrangement, WiMAX-type customer premises equipment (CPE)  122  may be located in a home or business to provide home or business customer broadband access to Internet  110  via base station  120 , ASN  118 , and home CSN  126  in a manner similar to access by subscriber station  116  via base station  114 , ASN  112 , and visited CSN  124 , a difference being that WiMAX CPE  122  is generally disposed in a stationary location, although it may be moved to different locations as needed, whereas subscriber station may be utilized at one or more locations if subscriber station  116  is within range of base station  114  for example. In accordance with one or more embodiments, operation support system (OSS)  128  may be part of network  100  to provide management functions for network  100  and to provide interfaces between functional entities of network  100 . Network  100  of  FIG. 1  is merely one type of wireless network showing a certain number of the components of network  100 , however the scope of the claimed subject matter is not limited in these respects. 
     Referring now to  FIG. 2 , a timeline diagram showing the utilization of a pseudo unavailability interval during which a subscriber station may send and/or receive traffic during a sleep mode in accordance with one or more embodiments will be discussed. As shown in  FIG. 2 , timeline  200  may represent a sleep-mode operation for subscriber station  116  of  FIG. 1  in which time may increase from left to right along timeline  200 . A sleep mode for subscriber station  116  may define a power saving mechanism to minimize power consumption of subscriber station  116  and to decrease usage of air-interface resources utilized by subscriber station  116  while maintaining communication of subscriber station  116  with network  100 . In one or more embodiment, such a sleep mode may be in compliance with an IEEE 802.16e standard, although the scope of the claimed subject matter is not limited in this respect. 
     During a sleep mode, timeline  200  may comprise one or more availability intervals (AI) such as availability interval  210 , availability interval  214 , availability interval  218 , availability interval  224 , and so on. Likewise, during a sleep mode, timeline  200  may comprise unavailability intervals (UAI) such as unavailability interval  212 , unavailability interval  216 , unavailability interval  222 , unavailability interval  226 , and so on. While in a sleep mode, subscriber station  116  may alternate between such periods of an availability interval and an unavailability interval. During an unavailability interval, subscriber station  116  may power down its radio interface, for example to conserve power consumption. During an availability interval, subscriber station  116  may power up its radio interface and listen for traffic indicator messages that may be sent by base station  114  to indicate the presence of traffic. The presence or absence of traffic for subscriber station  116  while in a sleep mode may be indicated by a traffic indicator message, which in one or more embodiments may be referred to as MOD-TRF-IND, which may be received by subscriber station  116  during an availability interval. In one or more embodiments, the duration of availability intervals such as AI  210 , AI  214 , AI  218 , and/or AI  224  may be constant. In one or more embodiments, the duration of unavailability intervals such as UAI  212 , UAI  216 , and/or UAI  222  may double for subsequent unavailability intervals up to a maximum value. Alternatively, the duration of unavailability intervals may remain constant for successive unavailability intervals. In one or more embodiments, the duration of first availability interval such as AI  210  may be denoted as Initial UAI, and the duration of an unavailability interval at a particular time may given by:
 
UAI=min(2*(Previous UAI), Final UAI base *2^(Final UAI exponent)  (1)
 
in which Final UAI base is the final UAI base and Final UAI exponent is the final UAI exponent. It may be noted that when Final UAI base=Initial UAI and Final UAI exponent=0, the duration of UAI is constant.
 
     In one or more embodiments, when subscriber station  116  is in a sleep mode, subscriber station  116  may power down during an unavailability interval. During an availability interval, subscriber station may wake up by powering up to listen for traffic indicator messages, such as MOB-TRF-IND, during the availability interval. If subscriber station  116  receives a traffic indicator message, subscriber station  116  may respond as follows. 
     If the traffic indicator message indicates that there is no traffic for the subscriber station  116 , then subscriber station  116  may optionally go back to sleep, that is power down radio resources, after receiving the traffic indicator message. 
     If the traffic indicator message indicates that there is traffic for subscriber station  116 , then subscriber station  116  may receive downlink (DL) transmissions from base station  114  in the same and/or similar manner as in a state of normal operation during a remaining portion of the present availability interval. In one or more embodiments, normal operation may be defined as a state in which subscriber station  116  is not in a sleep mode. In one or more embodiments, if subscriber station  116  receives a positive traffic indicator message, the operation of subscriber station after an unavailability interval may depend on a traffic-triggered wakening flag, such as traffic_triggered_wakening_flag (TTW). In one or more embodiments, such a traffic-triggered wakening flag may be negotiated between base station  114  and subscriber station  116  prior subscriber station  116  entering a sleep mode. 
     In one or more embodiments, if the traffic-triggered wakening flag is set to zero (TTW=0), subscriber station  116  does not deactivate the sleep mode after receiving MOB-TRF-IND message with positive traffic indication. Therefore, subscriber station  116  may continue its sleep mode as usual. Such an option may allow subscriber station  116  to receive traffic during an availability interval without disrupting the sleep-mode operation of subscriber station  116 . This option enables subscriber station  116  to receive lighter traffic or more delay-tolerant traffic without terminating the sleep mode. When the traffic-triggered wakening flag is set to zero, subscriber station  116  may receive traffic during an availability interval. 
     In one or more embodiments, if the traffic-triggered wakening flag is set to one (TTW=1), subscriber station  116  may deactivate the sleep mode. Therefore, the sleep mode of subscriber station  116  is terminated, and subscriber station enters a normal mode of operation after receiving the MOB-TRF-IND message with positive traffic indication. 
     In one or more embodiments, traffic may be communicated between subscriber station  116  and base station  114  during a sleep mode without requiring subscriber station  116  to exit the sleep mode and communicate in a normal mode. In such embodiments, subscriber station  116  may utilize a pseudo unavailability interval (PUAI), such as PUAI  220  of  FIG. 2 . As shown in  FIG. 2 , a pseudo unavailability interval  220  may comprise at least a portion of an unavailability interval  222  that may be used, as needed, by subscriber station  116  to send and/or receive traffic without exiting and/or modifying sleep-mode operation. 
     In one or more embodiments as shown in  FIG. 2 , pseudo unavailability interval  220  may comprise a portion of unavailability interval  222 . Thus, in one or more embodiments, the aggregate duration of PUAI  220  and UAI  222  may comprise a duration of a single unavailability interval that may otherwise exist in the absence of PUAI  220 , for example as determined by Formula (1), above, for calculating the duration of an unavailability interval as previously discussed. While subscriber station  116  is in a sleep mode, during a pseudo unavailability interval such as PUAI  220 , base station  114  may send traffic to subscriber station  116  and/or subscriber station  116  may send traffic to base station  114 . In one or more embodiments, base station  114  may optionally specify the use of a pseudo unavailability interval and/or the duration of the pseudo unavailability interval. One example of how base station  114  may specify such a pseudo unavailability interval is shown in Table 1. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 PUAI message format. 
               
             
          
           
               
                   
                 Syntax 
                 Size 
                 Note 
               
               
                   
                   
               
             
          
           
               
                   
                 PUAI Flag 
                 1 
                 bit 
                 Indicate the presence or 
               
               
                   
                   
                   
                   
                 absence of PUAI 
               
               
                   
                 If (PUAI Flag) { 
               
               
                   
                 PUAI Length 
                 M 
                 bits 
                 Length of PUAI interval 
               
               
                   
                 } 
               
               
                   
                   
               
             
          
         
       
     
     As shown in Table 1, a PUAI message may contain a one bit PUAI Flag that indicates the presence or absence of a pseudo unavailability interval. If the PUAI Flag is positive indicating the presence of a PUAI, the PUAI message may indicate the length of the pseudo unavailability interval, for example by PUAI Length. In the event a pseudo unavailability interval is specified, one or more of the following techniques may be utilized to determine the duration of a next unavailability interval. 
     Method 1: The duration of a next UAI=duration of a current UAI. In one or more embodiments, Method 1 may be utilized to avoid and/or minimize an increase of the duration of the unavailability interval, for example if it is expected that additional traffic may be sent to subscriber station  116  during sleep mode. 
     Method 2: The duration of a next UAI may be calculated using Formula (1) or variations thereof. In one or more embodiments, Method 2 may be utilized if the probability of further traffic to or from subscriber station  116  is generally lower and/or the traffic does not have stringent delay requirements. Furthermore, in one or more embodiments Method 2 may be utilized to maximize and/or increase power saving. 
     Method 3: The duration of a next UAI=X*duration of a current UAI, where 0&lt;X&lt;1. In one or more embodiments, Method 3 may be utilized if more traffic is exists and/or is expected to be received by and/or sent by subscriber station  116 , and/or where the traffic has stringent delay requirements. In such embodiments, the duration of the next unavailability interval may be successively decreased, and the duration of the next pseudo unavailability interval may be successively increased. 
     Method 4: The relationship between the duration of a current UAI and a next UAI may be based at least in part on the type of traffic being transmitted and/or expected to be transmitted by or received by subscriber station  116 , for example based on the traffic load and/or delay requirements of the traffic. 
     Method 5: Duration of a next UAI may be independent of a duration of a current UAI. In one or more embodiments, Method 5 may be utilized to artificially reset the sleep-mode operation with an UAI of an arbitrary duration that is suitable to the current and/or expected traffic pattern. Method 5 may also be utilized to accommodate a change in traffic pattern that may occur in the middle of sleep-mode operation. For example, when a sleep mode is initiated the parameters for a UAI duration may be defined based on an existing and/or predicted traffic pattern for subscriber station  116 . In the event the traffic patterns change, subscriber station  116  may modify the UAI duration parameters. Such change may comprise selecting the duration of the next UAI to accommodate the new traffic patterns. 
     In one or more embodiments, the selected method to determine the duration of a next unavailability interval following a pseudo unavailability interval may be negotiated between base station  114  and subscriber station  116  during initiation of sleep mode prior to entry of subscriber station  116  into sleep mode. Alternatively, the method to determine the duration of a next unavailability interval may be exchanged between base station  114  and subscriber station  116  as a part of PUAI message as shown in Table 1, above. In the event a PUAI message is utilized to exchange such information pertaining to the duration of a next unavailability interval, the format for such a PUAI message may be as shown in Table 2. 
     
       
         
               
             
               
               
               
             
               
               
               
               
             
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 PUAI message format indicating the method used to determine the 
               
               
                 length of a next unavailability interval. 
               
             
          
           
               
                 Syntax 
                 Size 
                 Note 
               
               
                   
               
             
          
           
               
                 PUAI Flag 
                 1 
                 bit 
                 Indicate the presence or 
               
               
                   
                   
                   
                 absence of PUAI 
               
               
                 If (PUAI Flag) { 
                   
                   
                   
               
               
                 PUAI Length 
                 M 
                 bits 
                 Length of PUAI interval 
               
               
                 } 
                   
                   
                   
               
               
                 Next UAI duration method 
                 3 
                 bits 
                 Specifies the method used to 
               
               
                   
                   
                   
                 determine the duration of 
               
               
                   
                   
                   
                 UAI following the use of 
               
               
                   
                   
                   
                 PUAI. 000 to 101 are used 
               
               
                   
                   
                   
                 for Method 1 to Method 4, 
               
               
                   
                   
                   
                 respectively. 110-111 are 
               
               
                   
                   
                   
                 reserved for future use. 
               
               
                 If (Next UAI duration 
                   
                   
                   
               
               
                 method == 3) { 
                   
                   
                   
               
               
                 X 
                 N 
                 bits 
                 Specifies X used in Method 3 
               
               
                 } 
                   
                   
                   
               
               
                 If (Next UAI duration 
                   
                   
                   
               
               
                 method == 4) { 
                   
                   
                   
               
             
          
           
               
                 For future definition 
                 For 
                 Specifies the relationship 
               
               
                   
                 future 
                 between current UAI and 
               
               
                   
                 definition 
                 next UAI for Method 4 
               
               
                 } 
                   
                   
               
             
          
           
               
                 If (Next UAI duration 
                   
                   
                   
               
               
                 method == 5) { 
                   
                   
                   
               
               
                 Next UAI duration 
                 R 
                 bits 
                 Specifies the duration of 
               
               
                   
                   
                   
                 next UAI in terms of number 
               
               
                   
                   
                   
                 of frames for Method 5 
               
               
                 } 
               
               
                   
               
             
          
         
       
     
     In one or more embodiments, if the method utilized to determine the duration of a next UAI after the use of a PUAI is negotiated between base station  114  and subscriber station  116  at sleep initiation, the format of the message part, SLP-REQ, sleep sub header, and/or sleep extended sub header, that specifies the duration of a next UAI may be the same or similar to a corresponding section in Table 2. In one or more embodiments, the maximum length of PUAI  220  may be the length of a current UAI  222 . In such a case, PUAI  220  is not extended beyond the duration of a current UAI  222 . Thus, in such embodiments the sleep operation of subscriber station is affected for the duration of the current UAI via implementation of a PAUI, and the sleep operation reverts to a normal sleep mode after the end of the current UAI. In the event subscriber station  116  still has more traffic to send and/or receive after the end of the current UAI, in one or more embodiments base station  114  and subscriber station  116  may exchange another PUAI message during the next AI and use a PUAI during the next UAI to continue traffic exchange. Such a process of using multiple successive PUAIs may continue until subscriber station  116  does not have any further traffic to send and/or receive. Such PUAI usage may optionally be initiated either by base station  114  or the subscriber station  116 . Base station  114  may initiate the utilization of one or more PUAIs if base station  114  has downlink traffic for subscriber station  116 , or subscriber station  116  may initiate the utilization of one or more PUAIs if subscriber station  116  has uplink traffic to transmit to base station  114 . In such arrangements, once base station  114  and/or subscriber station  116  complete exchanging the traffic, subscriber station  116  may return to a normal sleep-mode operation automatically. Therefore, in such embodiments, there may be no need to terminate and then reinitiate the sleep mode since subscriber station  116  may remain in sleep mode during the exchange of traffic via one or more PUAIs. However, these are merely example arrangements of the utilization of one or more PUAIs, and the scope of the claimed subject matter is not limited in these respects. 
     In one or more embodiments, if the PUAI needs to be extended beyond one or more UAIs, the repeated use of a PUAI message during multiple AI, may increase the signaling load. Thus, in one or more embodiments, the length of a PUAI may be greater than the length of the next UAI. In such embodiments, the PUAI may span more than one UAI and/or AI durations. When this option is selected, the PUAI message may be used to specify the number of sleep cycles, that is the number of UAI and/or AI intervals for which the sleep operation is suspended. Thus, instead of alternating between the AI and UAI intervals, while in sleep mode subscriber station  116  remains available to send and/or receive data and/or management traffic. Once the specified number of UAI intervals and/or AI intervals scheduled for PUAI are exhausted, the sleep operation of subscriber station  116  may be resumed automatically. As a result, the signaling overhead to transmit the PUAI indication and sleep termination and initiation are reduced and/or eliminated. When the PUAI indication flag is positive, two possibilities may occur. In one case, the PUAI duration may be less than or equal to the next UAI. In another case, the PUAI duration may not be limited by the duration of the next UAI. One embodiment for a PUAI format to accommodate the two cases is shown in Table 3. 
     
       
         
               
             
               
               
               
             
               
               
               
               
             
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 PUAI message format when the PUAI 
               
               
                 duration can be larger than next UAI. 
               
             
          
           
               
                 Syntax 
                 Size 
                 Note 
               
               
                   
               
             
          
           
               
                 PUAI Flag 
                 1 
                 bit 
                 Indicate the presence or 
               
               
                   
                   
                   
                 absence of PUAI 
               
               
                 PUAI Type 
                 1 
                 bit 
                 0: PUAI length is less than 
               
               
                   
                   
                   
                 or equal to the next UAI 
               
               
                   
                   
                   
                 1: PUAI length is not 
               
               
                   
                   
                   
                 restricted by the duration of 
               
               
                   
                   
                   
                 next UAI can extend 
               
               
                   
                   
                   
                 multiple UAI and Al 
               
               
                 If (PUAI Flag) &amp;&amp; (!PUAI 
                   
                   
                   
               
               
                 Type) { 
                   
                   
                   
               
               
                 PUAI Length 
                 M 
                 bits 
                 Length of PUAI interval 
               
               
                 } 
                   
                   
                   
               
               
                 Else if (PUAI Flag) &amp;&amp; 
                   
                   
                   
               
               
                 (PUAI Type) { 
                   
                   
                   
               
               
                 PUAI Length 
                 N 
                 bits 
                 N is the number of UAI and 
               
               
                   
                   
                   
                 AI cycles that constitutes 
               
               
                   
                   
                   
                 PUAI duration. After N 
               
               
                   
                   
                   
                 number of UAI and AI 
               
               
                   
                   
                   
                 cycles, the MS automatically 
               
               
                   
                   
                   
                 returns to sleep operation. 
               
               
                 } 
                   
                   
                   
               
               
                 Next UAI duration method 
                 3 
                 bits 
                 Specifies the method used to 
               
               
                   
                   
                   
                 determine the duration of 
               
               
                   
                   
                   
                 UAI following the use of 
               
               
                   
                   
                   
                 PUAI. 000 to 101 are used 
               
               
                   
                   
                   
                 for Method 1 to Method 4, 
               
               
                   
                   
                   
                 respectively. 110-111 are 
               
               
                   
                   
                   
                 reserved for future use. 
               
               
                 If (Next UAI duration 
                   
                   
                   
               
               
                 method == 3) { 
                   
                   
                   
               
               
                 X 
                 N 
                 bits 
                 Specifies X used in Method 3 
               
               
                 } 
                   
                   
                   
               
               
                 If (Next UAI duration 
                   
                   
                   
               
               
                 method == 4) { 
                   
                   
                   
               
             
          
           
               
                 For future definition 
                 For 
                 Specifies the relationship 
               
               
                   
                 future 
                 between current UAI and 
               
               
                   
                 definition 
                 next UAI for Method 4 
               
               
                 } 
                   
                   
               
             
          
           
               
                 If (Next UAI duration 
                   
                   
                   
               
               
                 method == 5) { 
                   
                   
                   
               
               
                 Next UAI duration 
                 R 
                 bits 
                 Specifies the duration of 
               
               
                   
                   
                   
                 next UAI in terms of number 
               
               
                   
                   
                   
                 of frames for Method 5 
               
               
                 } 
               
               
                   
               
             
          
         
       
     
     Table 3 illustrates one embodiment to accommodate the two cases, however in other embodiments other PUAI formats may be utilized to extend the PUAI beyond next UAI, and the scope of the claimed subject matter is not limited in this respect. The duration of a next UAI upon the resumption of sleep operation may be indicated using any one or more of Method 1 through Method 5 as discussed, above for both cases, for example the case where the PUAI is limited by the duration of the next UAI and/or when the PUAI is not limited by the duration of the next UAI, and the scope of the claimed subject matter is not limited in these respects. 
     In one or more embodiments, the PUAI message may be transmitted by base station  114  in the downlink from base station  114  to subscriber station  116 . Alternatively, the PUAI message may be transmitted by subscriber station  116  in an uplink from subscriber station  116  to base station  114 . In the downlink, base station  114  is capable of utilizing one or more of the following mechanisms to transmit the PUAI message to subscriber station  116  while subscriber station  116  is in a sleep mode. 
     MOB-TRF-IND message: Base station  114  sends MOB-TRF-IND message during an AI interval of subscriber station  116  while subscriber station  116  is in sleep mode. Base station  114  sends the PUAI message as a part of this MOB-TRF-IND message. 
     PUAI sub-header: Base station  114  appends the PUAI message to other media access control (MAC) messages using a PUAI sub-header. In one or more embodiments, such sub-headers may be in compliance with an IEEE 802.16e standard. The PUAI sub-header method may be utilized for example if base station  114  has other MAC messages to send to subscriber station. 
     Separate MAC management message: In the event that base station  114  does not have an opportunity to piggyback the PUAI message onto other MAC messages as a PUAI sub-header, base station  114  optionally may send the PUAI message as a separate MAC management message. 
     Portion of the Generic MAC Header: MAC messages sent by base station  114  to subscriber station typically have a Generic MAC Header (GMH). A portion of the GMH, for example a few bits in the GMH, optionally may be utilized by base station  114  to convey the PUAI message. Since a portion of the GMH may be utilized, in one or more embodiments the entire PUAI message may not be sent using this method. In such embodiments, a more concise PUAI message format may be defined for this purpose. For example, one bit in the GMH may be utilized to indicate if a particular message is the last one for subscriber station. If so indicates, subscriber station  116  may return to sleep after receiving a message with positive indication in this bit. 
     For usage of one or more of the above downlink mechanisms, base station  114  may implement the following method in one or more embodiments. If several subscriber stations  116  are being woken up from sleep at the same time, or nearly the same time, base station  114  may insert the identifications (IDs) of such subscriber stations  116  into a single traffic indicator message (TRF_IND) in such a manner that the overhead may be highly amortized among several subscriber stations  116  with fewer and/or a single message while maintaining reliability of communication and management. If a subscriber station  116  is already currently awake and base station  114  wants to extend the awake time of the subscriber station, base station  114  may implement any one or more of a PUAI sub-header, a separate MAC management message, and/or the Generic MAC Header as indicated above, or combinations thereof. 
     Likewise, in one or more embodiments, for the uplink subscriber station  116  may implement any one or more of the following mechanisms to transmit a PUAI message to base station  114 . 
     PUAI sub-header: Subscriber station  116  appends the PUAI message to other MAC messages using a PUAI sub-header. A PUAI sub-header may be utilized when subscriber station  116  has other MAC messages to send to base station  114 . 
     Separate MAC management message: In the event that subscriber station  116  does not have an opportunity to piggyback the PUAI message onto other MAC messages, subscriber station  116  optionally may send the PUAI message as a separate MAC management message. 
     Portion of the Generic MAC Header: MAC message sent by subscriber station  116  to base station  114  typically includes a Generic MAC Header (GMH). A portion of the GMH, such as a few bits in the GMH, may be utilized by subscriber station  116  to convey the PUAI message. In one or more embodiments, the entire PUAI message may not be sent using this method. In such embodiments, a more concise PUAI message format may be defined for this purpose. For example, one bit in the GMH may be utilized to indicate if a particular message is the last one by subscriber station  116 . Subscriber station  116  may return to sleep after sending a message with positive indication in this bit. 
     The above downlink and uplink mechanisms for transmitting PUAI information are merely example methods, and other methods optionally may be utilized by base station  114  and/or subscriber station  116  to convey the PUAI message and/or a more concise format to convey a subset of information conveyed by the PUAI message. Thus, the scope of the claimed subject matters is not limited in these respects. 
     Referring now to  FIG. 3 , a flow diagram of a method for transferring information between a base station and a subscriber station in sleep mode via a pseudo unavailability interval in accordance with one or more embodiments will be discussed.  FIG. 3  illustrates one particular order of the blocks of method  300 , however the order of the blocks may be changed to other orders, and method  300  may comprise more or fewer blocks than shown in  FIG. 3 , and the scope of the claimed subject matter is not limited in these respects. At block  310 , data may be available to be transmitted, for example from base station  114  to subscriber station  116 , or from subscriber station  116  to base station  114 . Thus, method  300  may be executed by base station  114  or by subscriber station  116 , alone or in combination. The device having data to be transmitted may be referred to as the transmitting device, and the device receiving the data to be transmitted may be referred to as the receiving device. Once data is available to be transmitted and/or exchanged, a pseudo unavailability interval (PUAI) indicator message may be transmitted at block  312  to a receiving device during an availability interval (AI) of subscriber station  116  in sleep mode. The PUAI indicator message transmitted at block  312  indicates to the receiving device the intent to transmit information during a next unavailability interval (UAI) of the sleep mode. The PUAI indicator message transmitted at block  312  may also indicate to the receiving device the length of the PUAI needed to transmit the data, and also optionally a method to be used to determine the length of the next UAI as determined at block  314 . The length of the next UAI may be determined at block  314 , for example as discussed herein, and data may be transmitted during the next UAI via a PUAI at block  316 . At the end of the PUAI, a determination may be made at decision block  318  whether there is any additional data remaining to be transferred. In the event there is additional data remaining, the transmitting device may indicate that one or more additional PUAIs will be used to transmit the additional data by sending additional PUAI indicator messages during the next AI at block  312 . Method  300  may then continue until there is no remaining data to be transferred, and subscriber station  116  may return to a usual sleep mode operation at block  320 . Subscriber station  116  may remain in sleep mode until more data is available to be transmitted at which point method  300  may continue at block  310  to transmit the additional data. 
     Referring now to  FIG. 4 , a flow diagram of a method for transferring information between a base station and a subscriber station in sleep mode via a pseudo unavailability interval in which the pseudo unavailability interval may be longer than the next unavailability interval to accommodate larger amounts of data to be transferred in accordance with one or more embodiments will be discussed.  FIG. 4  illustrates one particular order of the blocks of method  400 , however the order of the blocks may be changed to other orders, and method  400  may comprise more or fewer blocks than shown in  FIG. 4 , and the scope of the claimed subject matter is not limited in these respects. At block  410 , data may be available to be transmitted, for example from base station  114  to subscriber station  116 , or from subscriber station  116  to base station  114 . Thus, method  400  may be executed by base station  114  or by subscriber station  116 , alone or in combination. The device having data to be transmitted may be referred to as the transmitting device, and the device receiving the data to be transmitted may be referred to as the receiving device. In the event that data is available to be transmitted at block  410 , the length of the next UAI may be determined at block  412 , for example using one or more of the methods described herein. A determination may be made at decision block  414  whether the length of the PUAI needed to transmit the data to be transmitted is greater than the length of the next UAI. In the event that the needed PUAI is greater than the next UAI, a determination may be made at block  416  the number of sleep cycles required to implement the needed PUAI, that is the number of repeated AI and UAI intervals. In any event, the PUAI indicator message may be transmitted at block  418  during the next AI. The PUAI indicator message transmitted at block  418  indicates to the receiving device the intent to transmit information during a next unavailability interval (UAI) of the sleep mode. The PUAI indicator message transmitted at block  418  may also indicate to the receiving device the length of the PUAI needed to transmit the data, and also optionally a method to be used to determine the length of the next UAI as determined at block  412 . Furthermore, if block  416  is executed, then the PUAI indicator may also indicate the number of sleep cycles needed to accommodate the PUAI. The data to be transmitted may then be transmitted during the next UAI via the PUAI at block  420  until all data has been sent and/or the end of the PUAI has been reached. Subscriber station  116  may then return to a usual sleep operation at block  422 , which may happen automatically, and remain in sleep operation until additional data is available to be transmitted at which time method  400  may continue at block  410 . 
     Referring now to  FIG. 5 , a block diagram of an information handling system capable of optimizing sleep mode operation in a wireless network in accordance with one or more embodiments will be discussed. Information handling system  500  of  FIG. 5  may tangibly embody one or more of any of the network elements of network  100  as shown in and described with respect to  FIG. 1 . For example, information handling system  500  may represent the hardware of base station  114  and/or subscriber station  116 , with greater or fewer components depending on the hardware specifications of the particular device or network element. Furthermore, such an information handling system  500  may be arranged to implement the timing and/or flow diagrams of  FIG. 2 ,  FIG. 3 , and/or  FIG. 4 , which may be for example embodied as instructions that may be stored on a storage medium and that are capable of being executed by information handling system  500  and/or a similar type of computing platform. Although information handling system  500  represents one example of several types of computing platforms, information handling system  500  may include more or fewer elements and/or different arrangements of elements than shown in  FIG. 5 , and the scope of the claimed subject matter is not limited in these respects. 
     Information handling system  500  may comprise one or more processors such as processor  510  and/or processor  512 , which may comprise one or more processing cores. One or more of processor  510  and/or processor  512  may couple to one or more memories  516  and/or  518  via memory bridge  514 , which may be disposed external to processors  510  and/or  512 , or alternatively at least partially disposed within one or more of processors  510  and/or  512 . Memory  516  and/or memory  518  may comprise various types of semiconductor based memory, for example volatile type memory and/or non-volatile type memory. Memory bridge  514  may couple to a graphics system  520  to drive a display device (not shown) coupled to information handling system  500 . 
     Information handling system  500  may further comprise input/output (I/O) bridge  522  to couple to various types of I/O systems. I/O system  524  may comprise, for example, a universal serial bus (USB) type system, an IEEE 1394 type system, or the like, to couple one or more peripheral devices to information handling system  500 . Bus system  526  may comprise one or more bus systems such as a peripheral component interconnect (PCI) express type bus or the like, to connect one or more peripheral devices to information handling system  500 . A hard disk drive (HDD) controller system  528  may couple one or more hard disk drives or the like to information handling system, for example Serial ATA type drives or the like, or alternatively a semiconductor based drive comprising flash memory, phase change, and/or chalcogenide type memory or the like. Switch  530  may be utilized to couple one or more switched devices to I/O bridge  522 , for example Gigabit Ethernet type devices or the like. Furthermore, as shown in  FIG. 5 , information handling system  500  may include a radio-frequency (RF) block  532  comprising RF circuits and devices for wireless communication with other wireless communication devices and/or via wireless networks such as network  100  of  FIG. 1 , for example where information handling system  500  embodies base station  114  and/or subscriber station  116 , although the scope of the claimed subject matter is not limited in this respect. 
       FIG. 6  depicts one embodiment of the subject matter disclosed herein that comprises an article of manufacture  600 . Article of manufacture  600  comprises a storage medium  601  having instructions  602  stored thereon that, if executed, result in a transmitter transmitting a pseudo unavailability interval indicator message in the event data is available to be transmitted to a receiver; and transmitting the data during a next unavailability interval of a sleep mode operation via a pseudo unavailability interval. In one embodiment, instructions  602 , if executed, further result in determining a length of the next unavailability interval, and transmitting the length of the next unavailability interval as part of the pseudo unavailability interval indicator message. In another embodiment, the transmitting of the pseudo unavailability interval indicator message occurs during an availability interval of a sleep mode operation, and instructions  602 , if executed, further result in, in the event there is additional data to be transmitted, transmitting one or more additional pseudo unavailability interval indicator messages and transmitting the additional data via one or more additional pseudo unavailability intervals until there is no additional data to be transmitted. In yet another embodiment, instructions  602 , if executed, further result in determining a length of the next unavailability interval, and if the needed length of the pseudo unavailability interval to transmit the data is greater than the length of the next unavailability interval, a number of sleep cycles is determined to accommodate the needed length of the pseudo unavailability interval, and the transmitting the data is executed during a next unavailability interval of a sleep mode operation via the pseudo unavailability interval for the determined number of sleep cycles. In still another embodiment, the pseudo unavailability interval indicator message comprise an indicator whether a duration of the next pseudo unavailability interval is based at least in part on a duration of a previous pseudo unavailability interval for the data to be transmitted. In another embodiment, instructions  602 , if executed, further result in returning to a normal sleep mode operation after the data has been transmitted. In yet another embodiment, instructions  602 , if executed, further result in otherwise remaining in a sleep mode for a predetermined duration. In another embodiment, the pseudo unavailability interval indicator message is transmitted as part of a traffic indicator message, as a sub-header to a media access control message, as a separate media access control message, as a portion of a generic media access control header, or combinations thereof. In still another embodiment, the pseudo unavailability interval indicator message specifies a calculation method for calculating length of the next unavailability interval, the calculation method comprising setting the length of the next unavailability interval to a length of the current unavailability interval, calculating the length of the next unavailability interval based at least in part on a formula that successively increases length of the unavailability interval in the absence of further traffic, setting the length of the next unavailability interval to a fraction of a length of the current unavailability interval, setting the length of the next unavailability interval based at least in part on existing traffic class or expected traffic class, or combinations thereof, or setting the length of the next unavailability interval independent of the length of the current unavailability interval, or combinations thereof. 
     Although the claimed subject matter has been described with a certain degree of particularity, it should be recognized that elements thereof may be altered by persons skilled in the art without departing from the spirit and/or scope of claimed subject matter. It is believed that the subject matter pertaining to sleep optimization for mobile devices in a wireless network and/or many of its attendant utilities will be understood by the forgoing description, and it will be apparent that various changes may be made in the form, construction and/or arrangement of the components thereof without departing from the scope and/or spirit of the claimed subject matter or without sacrificing all of its material advantages, the form herein before described being merely an explanatory embodiment thereof, and/or further without providing substantial change thereto. It is the intention of the claims to encompass and/or include such changes.