| Apollo is an innovative software product coming to revolutionize the wireless backhaul market by delivering unparalleled performance and advanced QoS over standard WIFI hardware.
Apollo enables OEMs and ODMs to deliver wireless broadband backhaul solutions that are future-proof, robust and cost-efficient.The license free technology eliminates recurrent leased-line expenditures and license fees, enabling low-cost communications ideal for low ARPU. Though 802.11 technologies operate in unlicensed bands, the deterioration of bandwidth in outdoor environments and the lack of a sophisticated QoS to deterministically control the air interface does not allow the application of this widespread technology to backhaul solutions. Antcor’s Apollo proprietary technology is coping with the pitfalls of 802.11 by completely redesigning the MAC layer, achieving a combination of superior performance and sophisticated QoS over standard WIFI hardware. The key-concept is the implementation of an adaptive polling mechanism to dynamically allocate bandwidth in the direction needed, thus increasing link efficiency and greatly decreasing the impact that distance has on throughput of the link. Selective repeat ARQ technology and packet aggregation further increase performance unleashing the power of WIFI to outdoor environments. |
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Apollo Architecture
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Convergence Sublayer
The convergence sublayer is the top part of the Apollo stack and handles higher layer traffic coming in and out of the Apollo MAC. Apollo convergence sublayer can be used as a transport for all packet-based protocols such as Internet Protocol (IP), Point-to-Point Protocol (PPP) and IEEE 802.3 (Ethernet).
The most important function performed at the CS is the process of Classification: Each packet is classified to an Apollo Connection and enqueued in the appropriate Connection Queue. The Classification process is performed by evaluating a set of user-defined rules based on the packet’s contents. For example, a packet can be classified to a Real Time or Best Effort connection depending on the specific value of the IP Protocol Field or the TCP/UDP Source/Destination Port. -
Connection Manager
Apollo is based on a connection oriented 802.16-like architecture suitable for providing QoS for Best Effort (BE) and Real Time (RT) traffic. An Apollo Connection can be seen as an independent transport channel. Each connection is associated with a scheduling service (e.g. BE or RT), a set of user defined QoS constraints and transmission options such as TCP Optimization or Automatic Repeat Request (ARQ). An Apollo Base Station maintains separate connections for each associated Subscriber Station.
Tcp Optimizer
The TCP Optimization Module optimizes TCP acknowledgement delivery over the Apollo Protocol. Since TCP acknowledgment packets play a very important role in most of TCP protocol’s congestion control algorithms, this leads to increased overall TCP throughput and fairness.
ARQ
Apollo handles loss detection and retransmissions by utilizing a selective repeat Automatic Repeat Request (ARQ) mechanism. Instead of transmitting an acknowledgment for each frame, APOLLO uses Bulk-Acknowledgments that correspond to burst of packets. The Bulk-Ack contains the information that is necessary in order to detect which frames of the burst were lost. Upon reception of this special acknowledgment a node selectively retransmits the lost frames. This technique is more suitable for outdoor environments since it minimizes the periods of inactivity between successive transmissions. In this way, a sender can rapidly transmit a burst of packets rather than wait for an Ack after each packet.
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Schedulers
The Scheduler engine is responsible for the optimal and fair allocation of uplink/downlink resources according to the specific requirements of each traffic class. The goal is to maintain high throughput for Best Effort connections while satisfying the delay/jitter constraints for Real Time traffic. When the system’s state machine indicates it’s time for a scheduling decision, the scheduler examines the state of all active connections and outputs a list that defines which connections will be granted access to the link and the amount of data that will be transmitted by each of them. -
FSM
The State Machine implements the core of the Apollo Polling Protocol. It is responsible for sequencing all the necessary control operations such as registration and the exchange of Apollo Protocol/Data Packets. The Base Station State Machine allocates the air interface according to the scheduler’s output by sending special Poll Grant Protocol Packets. Since a Subscriber Station is not authorized to access the medium without a grant from the Base Station, the link allocation is deterministic and completely controlled. In addition, the Apollo State Machine guarantees that the link is allocated to a single node at each time instant, thus eliminating the traditional hidden node problems. -
Packet Manager
The Packet Manager handles the encapsulation/decapsulation of Apollo Protocol Packets. This module also performs frame aggregation – a technique that leads to higher link utilization and significant reduction of the overall system load (since less frames need to be processed per time unit).
Minimal 802.11 MAC
When operating under Apollo, the legacy 802.11 wireless stack is stripped down to the minimum basic transmission/reception functionality (802.11 frame encapsulation/decapsulation, DMA operations and Interrupt handling) that is necessary in order to support the polling scheme. Moreover, two significant features of 802.11 protocol are disabled. The first one is the medium access back-off (CSMA) which is disabled because APOLLO does not rely on any form of contention, and the second one is the 802.11 Acknowledgment mechanism which is replaced by a custom ARQ (Automatic Repeat reQuest) protocol. -
MIB
The Apollo Management Information Base provides the necessary services for managing the Apollo stack (e.g. setting classifiers, adding connections) and retrieving information on the status of the Apollo stack.
Apollo Downloads
Here you can download documentation of Apollo product. Please select the appropriate file from below list.
Apollo Documentation
Apollo Documentation
