The Self Adapting for Wireless Sensor Network Receiver Initiated the
MAC Protocol :
Energy efficiency is the major leitmotiv in designing of the
Medium Access Control that is MAC protocol for the Wireless Sensor
Networks. In this scheme, the receiver initiates the process that allow
two nodes to agree on the rendezvous to communicate: all the nodes are
periodically broad cast the beacon frames that indicate that they
are going to the listening for a short duration. In addition,
nodes intending to send a packet periodically poll the medium
until they hear beacon frame of the intended destination.
These two periods are different from others . This in effect decorrelates the
length of the attention signal on the medium that is preamble that
initiates the communication from sleep time of receiver
nodes. This paper presents the Self Adapting Receiver
Initiated the MAC protocol the SARI MAC which is a novel asynchronous
MAC protocol for energy constrained Wireless Sensor Networks.
SARI MAC self adapts to the traffic load to meet specified the
Quality of the Service requirements at lowest energy cost possible.
To do so, SARI-MAC relies on the traffic estimation , the duty-cycle
adaptation and the acknowledgement mechanisms. The performance
evaluation assesses the SARI MAC meets given Q o S requirements
in energy efficient manner and outperforms the state of
the art protocol of the RI-MAC in a broad range of traffic scenarios.
MAC protocol Limitations :
In wireless network nodes transmit packets in the unsynchronized fashion.Medium Access
Control protocol is responsible for co-ordinating multiple access to the shared channel minimizing conﬂicts. This multiple an access schemes can be classiﬁed as ﬁxed-assignment and demand assignment multi access schemes. Fixed-assignment multi access divides the available space of the
channel into subchannels with one subchannel assigned per every individual user. Demand assignment.
multi access allows the device to transmit immediately when data is available but this protocol which is
must account for the possibility of the contention when two or more devices simultaneously transmission.
Q1: Give the Classifications of MAC Protocols ?
Ans: Contention-based protocols with reservation
Support real-time traffic
Reserve bandwidth a priori
The Global time synchronization is difficult to achieve
Not require global synchronization
contention based protocols with the scheduling
Packet scheduling at nodes and
Scheduling the nodes for access to the channel.
Q2 : Devide the transmission channel ?
Ans: transmission channel is divided into:
The data channel
data packet transmission
The control channel
RTS, CTS, busy tones.
Q3: Use two busy tones on the control channel , BT t and BT r?
Ans: BT t : indicate that it is transmitting on the data channel
BT r : indicate that it is receiving on the data channel
Two busy tone signals are 2 sine waves at different Frequencies.
Q4:How many types the RI-BTMA protocol ?
Ans: Two types the basic protocol
No backlog buffers
packets which suffer collisions cannot be
the controlled protocol
backlog buffer is non-empty
Backlog buffers : the transmitting a backlogged packet in the next idle slot with a probability q.
transmitting the non-backlogged packet
in the next idle slot with the probability p.
Q5: What are Basic mechanisms of D P S ?
Ans: Piggyback information
Head-of-line (HoL) packet as the packet with the highest priority
RTS, CTS : carry current packet info