| | 65 | many Subscriber Stations '''(SS)''' forming a Star Topology. The BS broadcasts downlink and uplink maps periodically which tells a SS when would be |
| | 66 | its turn to send and receive data, as is done in 802.16 or Wimax. For the first implementation we have assumed the system to be in equilbrium |
| | 67 | i.e. no new SS`s are added to the system. Their is no notion of an ACK here and no contention issues. |
| | 68 | |
| | 69 | == == |
| | 70 | |
| | 71 | == == |
| | 72 | |
| | 73 | [[Image(P2MP.png, align=centre, 500)]] |
| | 74 | |
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| | 76 | == == |
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| | 81 | |
| | 82 | This behavioral description of both BS and SS can be transformed to state-machines, which in turn can be transformed to C-code. A few typical |
| | 83 | transitions through states are numbered. For the Base Station, we have the following states: |
| | 84 | |
| | 85 | [[Image(BS.bmp, align=left, 500)]] |
| | 86 | |
| | 87 | == == |
| | 88 | |
| | 89 | == == |
| | 90 | |
| | 91 | == == |
| | 92 | |
| | 93 | 1) '''Process Map''' : The BS decides the allocation of slots for the uplink and the downlink to the various SS. Each slot consists of the number |
| | 94 | of burst units allowed. For our TDM system we have assumed a equal slots for all the subscribers. Also, new Connection ID`s are allocated during |
| | 95 | this stage. |
| | 96 | |
| | 97 | 2) '''Send Map''' : The Base Station broadcasts the map created in the above stage, using a special '''Connection ID''' 0, meant for all the |
| | 98 | Subscriber nodes already in the system. |
| | 99 | |
| | 100 | 3)'''DL Burst''' : The BS emits on the DownLink as specified by Map transmitted in the previous stage. To distinguish between each of the SS |
| | 101 | it uses a Connection ID, which corresponds to its own queues. This can be heard by all the nodes and they too distinguish it by their |
| | 102 | Connection ID. |
| | 103 | |
| | 104 | 4) '''Contention Time''' : This stage is for future reserve. Any new SS wishing to join the system and already synchronized with BS would send in a Request |
| | 105 | during this stage. For the time being we make the BS and the SS sleep during this period. |
| | 106 | |
| | 107 | 5) '''UL Burst''' : The BS receives on the UpLink as specified by Map transmitted in the previous stage. Again it distinguishes between various SS`s |
| | 108 | by the use of Connection ID. |
| | 109 | |
| | 110 | 6) '''Map Sending''' : If the BS does not receive from any SS for a long time, it enters this special stage. After coming to this state, the BS |
| | 111 | emits MAPS Periodically and simply waits for the rest of the frame. |
| | 112 | |
| | 113 | |
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